Re: What do these '=?utf-8?' sequences mean in python?

[Peter Pearson]

On Sat, 6 May 2023 14:50:40 +0100, Chris Green  wrote:
[snip]
> So, what do those =?utf-8? and ?= sequences mean?  Are they part of
> the string or are they wrapped around the string on output as a way to
> show that it's utf-8 encoded?

Yes, "=?utf-8?" signals "MIME header encoding".

I've only blundered about briefly in this area, but I think you
need to make sure that all header values you work with have been
converted to UTF-8 before proceeding.  
Here's the code that seemed to work for me:

def mime_decode_single(pair):
"""Decode a single (bytestring, charset) pair.
"""
b, charset = pair
result = b if isinstance(b, str) else b.decode(
charset if charset else "utf-8")
return result

def mime_decode(s):
"""Decode a MIME-header-encoded character string.
"""
decoded_pairs = email.header.decode_header(s)
return "".join(mime_decode_single(d) for d in decoded_pairs)



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Re: Precision Tail-off?

[Peter Pearson]

On Fri, 17 Feb 2023 10:27:08, Stephen Tucker wrote:[Head-posting undone.]
> On Thu, Feb 16, 2023 at 6:49 PM Peter Pearson 
> wrote:
>> On Tue, 14 Feb 2023 11:17:20 +, Oscar Benjamin wrote:
>> > On Tue, 14 Feb 2023 at 07:12, Stephen Tucker 
>> wrote:
>> [snip]
>> >> I have just produced the following log in IDLE (admittedly, in Python
>> >> 2.7.10 and, yes I know that it has been superseded).
>> >>
>> >> It appears to show a precision tail-off as the supplied float gets
>> bigger.
>> [snip]
>> >>
>> >> For your information, the first 20 significant figures of the cube root
>> in
>> >> question are:
>> >>49793385921817447440
>> >>
>> >> Stephen Tucker.
>> >> --
>> >> >>> 123.456789 ** (1.0 / 3.0)
>> >> 4.979338592181744
>> >> >>> 1234567890. ** (1.0 / 3.0)
>> >> 49793385921817.36
>> >
>> > You need to be aware that 1.0/3.0 is a float that is not exactly equal
>> > to 1/3 ...
>> [snip]
>> > SymPy again:
>> >
>> > In [37]: a, x = symbols('a, x')
>> >
>> > In [38]: print(series(a**x, x, Rational(1, 3), 2))
>> > a**(1/3) + a**(1/3)*(x - 1/3)*log(a) + O((x - 1/3)**2, (x, 1/3))
>> >
>> > You can see that the leading relative error term from x being not
>> > quite equal to 1/3 is proportional to the log of the base. You should
>> > expect this difference to grow approximately linearly as you keep
>> > adding more zeros in the base.
>>
>> Marvelous.  Thank you.
[snip]
> Now consider appending three zeroes to the right-hand end of N (let's call
> it NZZZ) and NZZZ's infinitely-precise cube root (RootNZZZ).
>
> The *only *difference between RootN and RootNZZZ is that the decimal point
> in RootNZZZ is one place further to the right than the decimal point in
> RootN.
>
> None of the digits in RootNZZZ's string should be different from the
> corresponding digits in RootN.
>
> I rest my case.
[snip]


I believe the pivotal point of Oscar Benjamin's explanation is
that within the constraints of limited-precision binary floating-point
numbers, the exponent of 1/3 cannot be represented precisely, and
is in practice represented by something slightly smaller than 1/3;
and accordingly, when you multiply your argument by 1000, its
not-quit-cube-root gets multiplied by something slightly smaller
than 10, which is why the number of figures matching the "right"
answer gets steadily smaller.

Put slightly differently, the crux of the problem lies not in the
complicated process of exponentiation, but simply in the failure
to represent 1/3 exactly.  The fact that the exponent is slightly
less than 1/3 means that you would observe the steady loss of
agreement that you report, even if the exponentiation process
were perfect.

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Re: Precision Tail-off?

[Peter Pearson]

On Tue, 14 Feb 2023 11:17:20 +, Oscar Benjamin wrote:
> On Tue, 14 Feb 2023 at 07:12, Stephen Tucker  wrote:
[snip]
>> I have just produced the following log in IDLE (admittedly, in Python
>> 2.7.10 and, yes I know that it has been superseded).
>>
>> It appears to show a precision tail-off as the supplied float gets bigger.
[snip]
>>
>> For your information, the first 20 significant figures of the cube root in
>> question are:
>>49793385921817447440
>>
>> Stephen Tucker.
>> --
>> >>> 123.456789 ** (1.0 / 3.0)
>> 4.979338592181744
>> >>> 1234567890. ** (1.0 / 3.0)
>> 49793385921817.36
>
> You need to be aware that 1.0/3.0 is a float that is not exactly equal
> to 1/3 ...
[snip]
> SymPy again:
>
> In [37]: a, x = symbols('a, x')
>
> In [38]: print(series(a**x, x, Rational(1, 3), 2))
> a**(1/3) + a**(1/3)*(x - 1/3)*log(a) + O((x - 1/3)**2, (x, 1/3))
>
> You can see that the leading relative error term from x being not
> quite equal to 1/3 is proportional to the log of the base. You should
> expect this difference to grow approximately linearly as you keep
> adding more zeros in the base.

Marvelous.  Thank you.


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mailbox misbehavior with non-ASCII

[Peter Pearson]

The following code produces a nonsense result with the input 
described below:

import mailbox
box = mailbox.Maildir("/home/peter/Temp/temp",create=False)
x = box.values()[0]
h = x.get("X-DSPAM-Factors")
print(type(h))
# 

The output is the desired "str" when the message file contains this:

To: recipi...@example.com
Message-ID: <123>
Date: Sun, 24 Jul 2022 15:31:19 +
Subject: Blah blah
From: f...@from.com
X-DSPAM-Factors: a'b

xxx

... but if the apostrophe in "a'b" is replaced with a
RIGHT SINGLE QUOTATION MARK, the returned h is of type 
"email.header.Header", and seems to contain inscrutable garbage.

I realize that one should not put non-ASCII characters in
message headers, but of course I didn't put it there, it
just showed up, pretty much beyond my control.  And I realize
that when software is given input that breaks the rules, one
cannot expect optimal results, but I'd think an exception
would be the right answer.

Is this worth a bug report?

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Re: fill out bulletins

[Peter Pearson]

On Tue, 14 Jun 2022 00:41:07 +0200, jak  wrote:
[snip]
>
> If you are interested in seeing what I called "post office bulletin"
> (English is not my language and I don't know the name, sorry), you can
> find a sample pdf (fillable) but it works badly here:
>
> https://www.guardiacostiera.gov.it/venezia/Documents/Bollettino%20MOD.%20TD123.pdf


Are these "post office bulletins" always PDFs?


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Re: What to do to correct the error written below:

[Peter Pearson]

On Tue, 12 Apr 2022 04:56:22 -0700 (PDT), NArshad wrote:
>
>>By looping over elements in "books" and incrementing counter i,
>>which is used as an index both for "books" and for "students",
>>you will produce an error whenever the number of books exceeds
>>the number of students.  Is there some reason to assume that the
>>number of books cannot exceed the number of students?
>
> Since this is an online library the number of students can be any when
> compared to number of books or the number of students has nothing to
> do with the number of books.

1. The code assumes that the number of books does not exceed the
   number of students.

2. You report that the number of students has nothing to do with
   the number of books.

3. Therefore we have identified an erroneous assumption in the code.

Mystery solved.

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Re: What to do to correct the error written below:

[Peter Pearson]

On Mon, 11 Apr 2022 00:14:49 -0700 (PDT), NArshad wrote:
[snip]
> books = list(models.Book.objects.filter(isbn=i.isbn))
> students = list(models.Student.objects.filter(user=i.student_id))
> i=0
> for l in books:
> 
> t=(students[i].user,students[i].user_id,books[i].name,books[i].isbn,issuedBooks[0].issued_date,issuedBooks[0].expiry_date,fine)
> i=i+1
> details.append(t)
[snip]

Is this homework?  In this newsgroup, by custom, homework problems
should be announced as such, since the best answer to a homework
question is different from the best answer to a real-life problem.

Back to the problem:

By looping over elements in "books" and incrementing counter i,
which is used as an index both for "books" and for "students",
you will produce an error whenever the number of books exceeds
the number of students.  Is there some reason to assume that the
number of books cannot exceed the number of students?



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Re: What to do to correct the error written below:

[Peter Pearson]

On Sat, 9 Apr 2022 04:59:05 -0700 (PDT), NArshad  wrote:
> I have accidentally deleted one account in a Django project because of
> which one of the pages is no more accessible and is giving the error
> written below:
>
> IndexError at /view_issued_book/
> list index out of range
>
> and the error is in the line: 
>
> t=(students[i].user,students[i].user_id,books[i].name,books[i].isbn,issuedBooks[0].issued_date,issuedBooks[0].expiry_date,fine)
>  
[snip]

Without seeing more of the code, one can only guess, but it appears
that the data being processed reside in arrays named "students" and "books",
which are indexed by an integer i.  The "list index out of range" error
probably results from i being too large -- running off the end of the
array, perhaps because of the deleted account.  You could confirm this
by printing i, len(students), and len(books) just before the failing
line.

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Re: strange problem building non-pure wheel for apple M1 arm64

[Peter Pearson]

On Mon, 7 Mar 2022 16:22:10 +, Robin Becker  wrote:
[snip]
>
> gcc -bundle -undefined dynamic_lookup -g -arch arm64
[snip]
>   -L/usr/local/lib
>   -L/usr/lib
>   -L/Library/Frameworks/Python.framework/Versions/3.9/lib
>   -lfreetype 
[snip]
>
> ld: warning: ignoring file /usr/local/lib/libfreetype.dylib, building
>  for macOS-arm64 but attempting to link with file 
>  built for macOS-x86_64
>
> The above message seems bizarre; everything is compiled for arm64, but
> gcc doesn't want to use an arm64 dylib.
>
> Can macos experts assist?

I am not at all expert in MacOS or any of the specifics of this
problem, but I think you want to try to prove that the libfreetype
invoked by "-lfreetype" is built for macOS-arm64 rather than for 
macOS-x86-64.

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Re: A problem with itertools.groupby

[Peter Pearson]

On Fri, 17 Dec 2021 09:25:03 +0100, ast  wrote:
[snip]
>
> but:
>
> li = [grp for k, grp in groupby("aahfffddnnb")]
> list(li[0])
>
> []
>
> list(li[1])
>
> []
>
> It seems empty ... I don't understand why, this is
> the first read of an iterator, it should provide its
> data.

Baffling.  Here's a shorter and less readable illustration:


>>> list(groupby("aabbb"))
[('a', ), 
 ('b', )]
>>> list(groupby("aabbb"))[0]
('a', )
>>> list(list(groupby("aabbb"))[0][1])
[]


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Re: Recursion on list

[Peter Pearson]

On Thu, 4 Nov 2021 08:57:14 +0100, ast  wrote:
> > li = []
> > li.append(li)
> > li
> [[...]]
>
> >li[0][0][0][0]
> [[...]]
>
> That's funny

After the coming AI upheaval, such cruelty to machines will
be considered punishable and not funny.


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Re: installazione numpy

[Peter Pearson]

On Mon, 11 Oct 2021 07:56:27 +0200, stefano felli  wrote:
> l'installazione di numpy con
> pip install numpy
> fornisce errore
> Building wheel for numpy (PEP 517)
>
>  ERROR: Failed building wheel for numpy
> Failed to build numpy
> ERROR: Could not build wheels for numpy which use PEP 517 and cannot be
> installed directly

I've seen this problem attributed to a Python / Numpy version-number
conflict:

https://stackoverflow.com/questions/65708176/troubles-installing-numpy-1-19-5-with-python-3-9-1-on-macos-bigsur

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Re: nrfutil icorrect installation

[Peter Pearson]

On Fri, 8 Oct 2021 14:46:34 -0500, Gerhard van Rensburg wrote:
>
> I installed Python 3.10.0
> I then install
> pip install nrfutil
>
> When I try to run nrfutil, I get
> ModuleNotFoundError: No module named 'constants'

I just asked duckduckgo.com about "nrfutil constants", and
got this helpful-looking link:

https://devzone.nordicsemi.com/f/nordic-q-a/65889/nrfutil-modulenotfounderror-no-module-named-constants

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Re: on floating-point numbers

[Peter Pearson]

On Thu, 2 Sep 2021 07:54:27 -0700 (PDT), Julio Di Egidio wrote:
> On Thursday, 2 September 2021 at 16:51:24 UTC+2, Christian Gollwitzer wrote:
>> Am 02.09.21 um 16:49 schrieb Julio Di Egidio:
>> > On Thursday, 2 September 2021 at 16:41:38 UTC+2, Peter Pearson wrote: 
>> >> On Thu, 02 Sep 2021 10:51:03 -0300, Hope Rouselle wrote: 
>> > 
>> >>> 39.61 
>> >> 
>> >> Welcome to the exciting world of roundoff error: 
>> > 
>> > Welcome to the exiting world of Usenet. 
>> > 
>> > *Plonk*
>> 
>> Pretty harsh, isn't it? He gave a concise example of the same inaccuracy 
>> right afterwards. 
>
> And I thought you were not seeing my posts...
>
> Given that I have already given a full explanation, you guys, that you
> realise it or not, are simply adding noise for the usual pub-level
> discussion I must most charitably guess.
>
> Anyway, just my opinion.  (EOD.)


Although we are in the world of Usenet, comp.lang.python is by
no means typical of Usenet.  This is a positive, helpful, welcoming
community in which "Plonk", "EOD", and "RTFM" (appearing in another
post) are seldom seen, and in which I have never before seen the
suggestion that everybody else should be silent so that the silver
voice of the chosen one can be heard.


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Re: on floating-point numbers

[Peter Pearson]

On Thu, 02 Sep 2021 10:51:03 -0300, Hope Rouselle wrote:
>
 import sys
 sys.version
> '3.8.10 (tags/...
>
 ls = [7.23, 8.41, 6.15, 2.31, 7.73, 7.77]
 sum(ls)
> 39.594
>
 ls = [8.41, 6.15, 2.31, 7.73, 7.77, 7.23]
 sum(ls)
> 39.61


Welcome to the exciting world of roundoff error:

Python 3.5.3 (default, Jul  9 2020, 13:00:10) 
[GCC 6.3.0 20170516] on linux

>>> 0.1 + 0.2 + 9.3 == 0.1 + 9.3 + 0.2
False
>>> 


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Re: Ask for help on using re

[Peter Pearson]

On Thu, 5 Aug 2021 02:40:30 -0700 (PDT), Jach Feng  wrote:
  I want to distinguish between numbers with/without a dot attached:
 
 >>> text = 'ch 1. is\nch 23. is\nch 4 is\nch 56 is\n'
 >>> re.compile(r'ch \d{1,}[.]').findall(text)
  ['ch 1.', 'ch 23.']
 >>> re.compile(r'ch \d{1,}[^.]').findall(text)
  ['ch 23', 'ch 4 ', 'ch 56 ']
 
  I can guess why the 'ch 23' appears in the second list. But how to get
  rid of it?

>>> re.findall(r'ch \d+[^.0-9]', "ch 1. is ch 23. is ch 4 is ch 56 is ")
['ch 4 ', 'ch 56 ']

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Re: PYTHON

[Peter Pearson]

On Mon, 21 Jun 2021 10:33:26 +0530, Ayaana Soni  wrote:
> have installed python from your site. After installation my IDLE doesn't
> work.  IDLE is not in my search list. Plz help!!

"Your site" is ambiguous.

Does your computer run Windows, Linux, Apple something, ... ?

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Re: Comparing text strings

[Peter Pearson]

On Sun, 18 Apr 2021 06:38:16 GMT, Gilmeh Serda wrote:
> On Mon, 12 Apr 2021 16:11:21 -0700, Rich Shepard wrote:
>
>> All suggestions welcome.
>
> Assuming you want to know which is the oldest version and that the same 
> scheme is used all the time, could this work?
>
 s1='atftp-0.7.2-x86_64-2_SBo.tgz'
 s2='atftp-0.7.4-x86_64-1_SBo.tgz'
 s1>s2
> False
 s2>s1
> True
[snip]

However, beware:

>>> s2='atftp-0.7.4-x86_64-1_SBo.tgz'
>>> s3='atftp-0.7.10-x86_64-1_SBo.tgz'
>>> s2>s3
True

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Re: Uninstall error

[Peter Pearson]

On Fri, 12 Mar 2021 17:52:33 +, Premmy  wrote:
> Hi. I am trying to uninstall python on my computer because i found a better
> one but its not getting deleted from control panel. can you please help me

Windows?  Apple?  Linux?

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Re: "unexpected argument"

[Peter Pearson]

On Tue, 9 Mar 2021 15:03:54 -0500, Quentin Bock  wrote:
> Error 1:
> Space Invaders.py:90: SyntaxWarning: "is" with a literal. Did you mean "=="?
>   if bullet_state is "fire":
>
> Error 2:
> line 66, in 
> if event.key == pygame.K_SPACE:
> AttributeError: 'Event' object has no attribute 'key'
>
> Code:
> import pygame
> import random
[snip]
>
> Why is it saying unexpected argument?
> Youtube Tutorial I'm Following:
> https://www.youtube.com/watch?v=FfWpgLFMI7w

Who is saying "unexpected argument"?  I see two error messages,
neither of which is "unexpected argument".  

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Re: Not able to use python properly

[Peter Pearson]

On Sat, 27 Feb 2021 17:45:42 -0500, Sahaj Verma  wrote:
> 
>
>I am not able to install and use pip .
>
>I have installed python 3.9.2 version on my laptop but I am unable to use
>pip function.
>
>Kindly look into this matter as soon as possible.
>
>Thanking You.
>
>Sahaj Verma
>
> 
>
>Sent from [1]Mail for Windows 10
>
> 
>
> References
>
>Visible links
>1. https://go.microsoft.com/fwlink/?LinkId=550986

Your chances of getting useful help will be much improved
if you provide more information.  "I am unable to use
pip function" could result from many varied causes.  Is
your screen completely black?


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Re: Python cannot count apparently

[Peter Pearson]

On Sun, 7 Feb 2021 20:49:52 + (UTC), Kevin M. Wilson wrote:

> Set i = 0 at the begin of the code, that way each entry starts at
> Logical 0 of the array/container/list...

No.  The original code, as posted, was

>>I recently coded this snippet of code:
>>myString=„hello“
>>for i in range(len(myString):
>> print(string[i])

Setting i=0 before the "for" statement would make no difference.
In the first pass through the for loop, i is set to the first
value in the range, which is zero.



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Re: A beginning beginner's question about input, output and . . .

[Peter Pearson]

On Wed, 13 Jan 2021 21:46:08 - (UTC), Grant Edwards wrote:
> On 2021-01-13, Peter Pearson  wrote:
[snip]
>> Browsergui is not widely popular (I don't think anybody but me has
>> mentioned it on this newsgroup), but it was written to be simple and
>> Pythonic, and has served me well.  Browsergui just uses your browser as
>> its user interface.  Grab it from
>>
>> https://github.com/speezepearson/browsergui
>
> I've been browsing through to documentation and examples, and I don't
> see any way to do any sort of modern flexible layout (e.g. nesting
> horizontal and vertical flexboxes) where you can control which
> elements grow/shrink when the window size changes.
>
> Is there a way to span columns/rows in a grid or control which columns
> grow/shrink?
>
> Have I missed something?

I doubt you've missed anything important, though I'm not sure because
I haven't done any of the things you mention.  Browsergui is minimalist.
If you've done the "python -m browsergui.examples" and don't see 
something like what you want, it's probably not there.

I like Browsergui for simple tools that require a little more
interaction than straight command-line utilities: exploring the effect
of various value-settings on some curve on a graph, or exploring the
ranges of values in a CSV file, or (most recently) rearranging the
order of image files in a list.

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Re: A beginning beginner's question about input, output and . . .

[Peter Pearson]

On Mon, 11 Jan 2021 15:37:58 -0500, DonK  wrote:
[snip]
>
> I've seen some Python gui frameworks like Tkinter, PyQt, etc. but they
> look kinda like adding a family room onto a 1986 double wide mobile
> home, 

Agreed.

Browsergui is not widely popular (I don't think anybody but me has
mentioned it on this newsgroup), but it was written to be simple and
Pythonic, and has served me well.  Browsergui just uses your browser as
its user interface.  Grab it from

https://github.com/speezepearson/browsergui

then run "python -m browsergui.examples".

(Disclaimer/boast: I'm related to Browsergui's author.)

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Re: How to copy the entire outlook message content in python

[Peter Pearson]

On Tue, 29 Dec 2020 05:38:53 -0800 (PST), nikhil k wrote:
...[snip]...
> import win32com.client as win32  
>
> ### Functions
> def getMailBody(msgFile):
> start_text = ""
> end_text = ""
> with open(msgFile) as f:
> data=f.read()
> return data[data.find(start_text):data.find(end_text)+len(end_text)]
...[snip]...
>
>
> Below is the error I'm getting.
>==
>   File "C:\Python\Python38-32\lib\encodings\cp1252.py", line 23, in decode
> return codecs.charmap_decode(input,self.errors,decoding_table)[0]
> UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 924: 
> character maps to 

I'm not completely sure that it's the f.read() call that produces
the error, because you cut out the earlier lines of the error
message, but . . .

I think the problem is that the data in the file you're reading
do not represent a valid "encoding" of any character string,
using whatever encoding convention Python thinks you want to use.
Maybe Python is assuming you're using ASCII encoding; 0x81 is
certainly not a valid ASCII character.

I don't know how Outlook represents messages in its .msg files;
it's possible it packs ASCII text along with binary data.

Maybe you can find a Python package that reads .msg files.

Maybe you could read the file as a bytestring instead of as a
character string.


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Re: 2 sample chi-square test

[Peter Pearson]

On Tue, 29 Dec 2020 02:52:15 -0800 (PST), Priya Singh wrote:
[snip]
> I have two spectra with wavelength, flux, and error on flux. I want to
> find out the variability of these two spectra based on the 2 sample
> Chi-square test.  I am using following code:
>
> def compute_chi2_var(file1,file2,zemi,vmin,vmax):
> w1,f1,e1,c1,vel1 = get_spec_vel(dir_data+file1,zemi)
> id1 = np.where(np.logical_and(vel1 >= vmin, vel1 < vmax))[0]   
> w2,f2,e2,c2,vel2 = get_spec_vel(dir_data+file2,zemi)
> id2 = np.where(np.logical_and(vel2 >= vmin, vel2 < vmax))[0]
> f_int = interp1d(w1[id1], f1[id1]/c1[id1], kind='cubic')
> e_int = interp1d(w1[id1], e1[id1]/c1[id1], kind='cubic')  
> f_obs,e_obs  = f_int(w2[id2]), e_int(w2[id2]) 
> f_exp, e_exp = f2[id2]/c2[id2], e2[id2]/c2[id2]
> e_net = e_obs**2 + e_exp**2
> chi_square =  np.sum( (f_obs**2 -  f_exp**2)/e_net  )
> dof = len(f_obs) - 1
> pval = 1 - stats.chi2.cdf( chi_square, dof)
> print('%.10E' % pval)
>
> NN = 320
> compute_chi2_var(file7[NN],file14[NN],zemi[NN],vmin[NN],vmax[NN])
>
>
> I am running this code on many files, and I want to grab those pair of
> spectra where, the p-value of chi-squa is less than 10^(-8), for the
> change to be unlikely due to a random occurrence.
>
> Is my code right concept-wise? Because the chi-squ value is coming out
> to be very large (positive and negative), such that my p-value is
> always between 1 and 0 which I know from other's results not correct.
>
> Can anyone suggest me is the concept of 2-sample chi-squ applied by me
> is correct or not?

1. This is not really a Python question, is it?

2. Recommendation: test your chi-squared code on simpler sample data.

3. Observation: P-values *are* normally between 0 and 1.

4. Observation: chi-squared values are never negative.

5. Recommendation: Learn a little about the chi-squared distribution
   (but not on a Python newsgroup).  The chi-squared distribution with
   N degrees of freedom is the distribution expected for a quantity
   that is the sum of the squares of N normally distributed random
   variables with mean 0 and standard deviation 1.  If you expect
   f_obs to equal f_exp plus some normally distributed noise with
   mean 0 and standard deviation sigma, then (f_obs-f_exp)/sigma
   should be normally distributed with mean 0 and standard deviation 1.

6. Observation: (f_obs**2 -  f_exp**2)/e_net is probably not what
   you want, since it can be negative.  You probably want something
   like (f_obs-f_exp)**2/e_net.  But don't take my word for it.

Good luck.

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Re: EnvironmentError

[Peter Pearson]

On Thu, 19 Nov 2020 13:19:07 +0100, Usman Musa  wrote:
> When I try to install a package or upgrade pip,  using pip install I got
> this error massage.
>  WARNING: Retrying (Retry(total=4, connect=None, read=None,
> redirect=None, status=None)) after connection broken by
> 'SSLError(SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED]
> certificate verify failed: certificate is not yet valid (_ssl.c:1122)'))':
[snip]
> Please help me out

Just guessing, here.  Might "not yet valid" mean that your computer's
clock is set to 1970?

Is there any indication *whose* certificate is "not yet valid"?  E.g.,
some URL from which pip is trying to load things?

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Re: returning totals in functions of math

[Peter Pearson]

On Sun, 8 Nov 2020 13:50:19 -0500, Quentin Bock  wrote:
> Errors say that add takes 1 positional argument but 3 were given? Does this
> limit how many numbers I can have or do I need other variables?
> Here is what I have:
> def add(numbers):
>total = 1
>for x in numbers:
>   total += x
>return total
> print(add(1999, -672, 84))

Your function "add" expects a single argument that is a list
of numbers.  You're passing it three arguments, each a number.
Try add([1999, -672, 84]).

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Re: Is there a conflict of libraries here?

[Peter Pearson]

On Fri, 6 Nov 2020 02:25:25 -0500, Steve  wrote:
> In my program, I have the following lines of code: 
> import random
> import re
> import time
> import datetime

At this point, the name "datetime" points to a module.

> from datetime import timedelta
> from time import gmtime, strftime
> import winsound as ws  
> import sys
>
[snip]
>
>   from datetime import datetime

By that, you have reassigned the name "datetime" to point to a
class defined in the datetime module.

[snip]
>
> AttributeError: type object 'datetime.datetime' has no attribute
> 'datetime'

Right, because the name "datetime" points to the class datetime in the
module datetime.  The class, unlike the module, has no "datetime"
attribute.

Apologies if you already knew this.  I wasn't sure.

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Re: Best way to determine user's screensize?

[Peter Pearson]

On Sun, 1 Nov 2020 15:31:57 - (UTC), Grant Edwards wrote:
>
> I have no objection to saving the most recent window size and using
> that on the next startup, but I hate applications that force the
> _location_ of the window. I've configured my window manager to open
> windows where I want them opened, please respect that.

Hear, hear!

This user has invested a lot of time learning how to live comfortably
with his window manager.  When some upstart app invalidates that
knowledge and the corresponding deeply ingrained habits, it's a
big annoyance.

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Re: Problem saving datetime to file and reading it back for a calculation

[Peter Pearson]

On Sat, 10 Oct 2020 18:17:26 -0400, Steve  wrote:
> I would like to use the line:
> HoursDiff = int((d2-d1).total_seconds()/3600)
> to determine the difference in hours between two timedate entries.
>
> The variable d2 is from datetime.now()
> and d1 is read from a text file.
>
> I can save d2 to the file only if I convert it to string and, at a later
> date, it gets read back in as d1 as string.   The variable d1 as string will
> not work in the HoursDiff statement.
>
> To me, it looks like a problem in formatting.
> How do I fix this?

datetime.datetime.strftime and datetime.datetime.strptime ?

>>> t = datetime.datetime.now()
>>> t.strftime("%Y-%m-%d %H:%M:%S")
'2020-10-10 18:02:33'
>>> b = datetime.datetime.strptime("2020-09-09 12:34:56", "%Y-%m-%d %H:%M:%S")
>>> b.strftime("%Y-%m-%d %H:%M:%S")
'2020-09-09 12:34:56'
>>> 

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Python's carbon guilt

[Peter Pearson]

Python advocates might want to organize their thoughts on
this subject before their bosses spring the suggestion:

>From 
>https://www.sciencemag.org/news/2020/10/we-re-part-problem-astronomers-confront-their-role-and-vulnerability-climate-change
> :

. . . Astronomers should also abandon popular programming languages
such as Python in favor of efficient compiled languages. Languages
such as Fortran and C++, Zwart calculates, are more than 100 times
more carbon efficient than Python because they require fewer
operations.


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Re: Truncation error

[Peter Pearson]

On Wed, 7 Oct 2020 13:29:26 +0530, Meghna Karkera  wrote:
> On Wed, Oct 7, 2020, 11:24 Marco Sulla  wrote:
>> On Wed, 7 Oct 2020 at 05:23, Meghna Karkera  wrote:
>> >
>> > How is PYTHON better than other software's(MATLAB) in case of
>> > truncation or rounding off error.
>
>> [snip]
>
> When I use the same code in MATLAB I get the answer as 4.6e-06 and when I
> use the same code in PYTHON I get the answer as 4.7e-06. How do I know
> which is the most precise and accurate value. Actually the answer is a big
> matrix, I've only compared the first entry of the matrix.

I hope your big matrix has many elements much larger than 4.7e-06,
so that you don't really have to worry about which package has the
smaller roundoff error.  If you *are* in the situation of having to
worry about roundoff error, that's likely to mean that you have to
plan your entire computation around the goal of minimizing its
susceptibility to tiny amounts of noise, and that's a problem much
more complex than choosing a language.

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Re: ValueError: arrays must all be same length

[Peter Pearson]

On Fri, 2 Oct 2020 13:34:46 +0100, Shaozhong SHI  wrote:
> Hello,
>
> I got a json response from an API and tried to use pandas to put data into
> a dataframe.
>
> However, I kept getting this ValueError: arrays must all be same length.
>
> Can anyone help?
>
> The following is the json text.  Regards, Shao
>
> {
>   "locationId": "1-1004508435",
>   "providerId": "1-101641521",
...
[huge block removed]
...
>   "reportType": "Location"
> }
>   ]
> }
>
> In [ ]:
>
>
> In [25]:
> j
>
>
> import pandas as pd
>
> import json
>
> j = json.JSONDecoder().decode(req.text)  ###req.json
>
> df = pd.DataFrame.from_dict(j)

An important programming skill is paring back failing code to
create the smallest example that exhibits the failure.  Often, the
paring process reveals the problem; and if it doesn't, the shorter
code is more likely to attract help.

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Re: news.bbs.nz is spewing duplicates to comp.lang.python

[Peter Pearson]

On Tue, 21 Apr 2020 21:42:42 + (UTC), Eli the Bearded wrote:
> This just arrived at my newserver:
>
> Path: 
> reader2.panix.com!panix!goblin2!goblin.stu.neva.ru!news.unit0.net!2.eu.feeder.erje.net!4.us.feeder.erje.net!feeder.erje.net!xmission!csiph.com!news.bbs.nz!.POSTED.agency.bbs.nz!not-for-mail
> From: Eli the Bearded <*@eli.users.panix.com> (Eli the Bearded)
> Newsgroups: comp.lang.python
> Subject: Re: Getting a 401 from requests.get, but not when logging in via 
> the br
> Date: Mon, 20 Apr 2020 19:18:48 +1200
> Organization: fsxNet Usenet Gateway | bbs.nz/#fsxNet
> Message-ID: <3057175...@f38.n261.z1.binkp.net>
> References: <1492048...@f38.n261.z1.binkp.net>
> Mime-Version: 1.0
> Content-Type: text/plain; charset=us-ascii
> Content-Transfer-Encoding: 7bit
> Injection-Info: news.bbs.nz; 
> posting-host="8IWYKlztXHa0+IViEdY46zrq8kpk7dC9fTbT74JiSDQ";
>   logging-data="12595"; mail-complaints-to="ab...@news.bbs.nz"
> User-Agent: VSoup v1.2.9.47Beta [95/NT]
> X-Comment-To: dcwhatthe
> X-MailConverter: SoupGate-Win32 v1.05
> Lines: 36
>
> I find that very curious because the post is mine but which I
> sent out with these headers:
>
> Path: reader2.panix.com!panix!qz!not-for-mail
> From: Eli the Bearded <*@eli.users.panix.com>
> Newsgroups: comp.lang.python
> Subject: Re: Getting a 401 from requests.get, but not when logging in via 
> the browser.
> Date: Mon, 20 Apr 2020 19:18:48 + (UTC)
> Organization: Some absurd concept
> Lines: 37
> Message-ID: 
> References: <48a2e19c-0a52-4cfa-b498-15e3d15b6...@googlegroups.com>
> NNTP-Posting-Host: panix5.panix.com
> X-Trace: reader2.panix.com 1587410328 23363 166.84.1.5 (20 Apr 2020 
> 19:18:48 GMT)
> X-Complaints-To: ab...@panix.com
> NNTP-Posting-Date: Mon, 20 Apr 2020 19:18:48 + (UTC)
> X-Liz: It's actually happened, the entire Internet is a massive game of 
> Redcode
> X-Motto: "Erosion of rights never seems to reverse itself." -- kenny@panix
> X-US-Congress: Moronic Fucks.
> X-Attribution: EtB
> XFrom: is a real address
> Encrypted: double rot-13
> User-Agent: Vectrex rn 2.1 (beta)
>
> The timezone on the date header has changed, the subject has been
> truncated, the Path and injection info is all different, and most
> crucially, the MESSAGE-ID and REFERENCES are completely bogus.
> News servers rely on Message-ID to tell if a message is unique. Change
> it, and it is now a new message. Screwing up References: header while
> changing the Subject: is going to break news threading.
[snip]


Thank you for bringing this up.  I thought I was going crazy.


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Re: Help building python application from source

[Peter Pearson]

On Fri, 28 Feb 2020 18:49:58 -0800, Mr. Lee Chiffre wrote:
[snip]
> I am a python noob. This is why I ask the python masters. There is a
> python software I want to install on the server it is called Electrumx.
> https://github.com/kyuupichan/electrumx is the link. I am having troubles
> with installing this.
> The short version is I am wanting to build this python application and
> needed dependencies from source code all from a local directory without
> relying on the python pip package servers. I only run software I can
> compile from source code because this is the only way to trust open source
> software. I also want to archive the software I use and be able to install
> it on systems in a grid down situation without relying on other servers
> such as python package servers.

(To make OP's requirements plainly visible, note that this appears to
be a cryptocurrency application.)

I'd suggest that building everything from source code might not be a
realistic solution to your security concerns.  I don't know what your
threat model is, but if it's something like, "Hackers and gangsters
who scatter password-harvesting trojans across the globe and then shlurp
up what they can," you might find that you get better security by
generating your keys on a computer that never communicates with the
outside world.  

Your concerns are (1) that the random numbers from which your keys have
been corrupted to make them predictable, or (2) that malicious software
will send your keys to the bad guys.  Isolating the key-generation
machine takes care of #2.  If you have Python code for generating keys,
something as simple as XORing a fixed value of your choice with its
random numbers will take care of #1.  I admit that using an isolated
machine introduces a lot of inconveniences, but I bet it compares
favorably with building everything from source.

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Re: fugacity cofficient

[Peter Pearson]

On 17 Feb 2020 18:40:00 GMT, Peter Pearson  wrote:
>
> Welcome, Alberto.
>
> Can you make this look more like a Python question and less like a
> do-my-homework question?  Show us what you've tried.

Sorry.   I see you already did exactly that.

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Re: fugacity cofficient

[Peter Pearson]

On Sun, 16 Feb 2020 14:17:28 -0800 (PST), alberto wrote:
> Hi, 
> how I could realize a script to calculate fugacity coefficients
> with this formula
>
[snip]
>
> regards
>
> Alberto

Welcome, Alberto.

Can you make this look more like a Python question and less like a
do-my-homework question?  Show us what you've tried.

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Re: Help

[Peter Pearson]

On Sun, 12 Jan 2020 22:23:58 +0530, kiran chawan  wrote:
> Whenever Iam trying to run this 'New  latest version python software 3.8.4
> python ' but it doesn't show any install option tell me how  to run this
> software and install new latest version of python plz reply sir thank you

To get a useful answer, you'll need to provide more information.
What operating system are you running?  
Is there already some kind of Python environment on your machine?
Have you downloaded some specific Python file that you're trying to
run?  Where did you get it?

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Re: Complaints on installing packages

[Peter Pearson]

On Sun, 12 Jan 2020 15:21:52 +0100, ofomi matthew wrote:
> Good day Python Team,
> I'm Matt by name and I have been having difficulties in installing packages
> on my pycharm.it keeps telling me "error installing package". Please how do
> I rectify this issues step by step.
> Looking forward to get a response as soon as possible. Thank you

Welcome, Matt.

Your chances of getting an answer to your question would be much
improved if you included more information.  What is the package
that is being installed?  What command did you issue?  Was there
any additional information besides "error installing package"?

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Re: Randomizing Strings In A Microservices World

[Peter Pearson]

On Mon, 9 Dec 2019 21:38:43 -0600, Tim Daneliuk  wrote:
> On 12/9/19 8:54 PM, Dennis Lee Bieber wrote:
>> On Mon, 9 Dec 2019 18:52:11 -0600, Tim Daneliuk 
>> declaimed the following:
>> 
>>> - Each of these services needs to produce a string of ten digits
>>> guaranteed to be unique on a per service instance basis AND to not
>>> collide for - oh, let's say - forever :)s
>>>
>>> Can anyone suggest a randomization method that might achieve this
>>> efficiently?
>>>
>>> My first thought was to something like nanonseconds since the epoch
>>> plus something unique about the service instance - like it's IP?
>>> (This is in a K8s cluster) - to see the randomization and
>>> essentially eliminate the string being repeated.
>>>
>>> Ideas welcome ..
>> 
>>  Well, 10 digits is rather short, but studying
>> https://en.wikipedia.org/wiki/Universally_unique_identifier might provide
>> some ideas.
>
> For a variety of reasons the length of this string cannot exceed 10
> digits.  It is believed that - in this application - the consumption
> of values will be sparse over time.  All I really need is a high
> entropy way to select from among the billion possible values to
> minimize the possibility of collisions (which require retry and time
> we don't want to burn).

Just to be sure: you *are* aware that the "Birthday Paradox" says
that if you pick your 10-digit strings truly randomly, you'll probably
get a collision by the time of your 10**5th string . . . right?

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Re: graphics with python

[Peter Pearson]

On Thu, 24 Oct 2019 16:06:21 +0800, Maggie Q Roth  wrote:
[snip]
> Can you show me the correct way to programming with graphics?
>
> I want to take some action detection, for instance, recognize dancing etc.

That description of your goals is very vague.  The more specific you
can be about what you want to do, the more likely you are to get a
helpful response.

"Programming with graphics" sounds like drawing charts, or graphs,
or pictures, or games.

"Recognize dancing etc." sounds like image processing, maybe involving
huge neural networks.

The most useful thing you could provide would be a statement of the
form, "I want to produce software that will take X as input and produce
output Y."

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Re: Hello, I need help.

[Peter Pearson]

On Tue, 15 Oct 2019 18:57:04 +0300, Damla Pehlivan  wrote:
[snip]

> . . .  I downloaded the python program, and I
> also downloaded Pycharm to use it. To be fair, I do not know what I am
> doing, but I made some progress last night and I was happy about it. Today
> when I came back from university, I realised the program was updated, I
> updated it and now I cannot use it. When I clicked on it, it kept opening
> the modify tab. I did modify it and repaired it. But it kept not opening
> the actual program.

A clearer description of your situation would improve your odds
of getting a useful result.  For starters, what operating system
are you using?  What application presents the "modify tab" that
you mention?  Is this perhaps a problem with your software-installing
process, rather than with Python or with Pycharm?

Have you found a good Python tutorial?

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Re: Angular distribution rose diagram in Python

[Peter Pearson]

On Fri, 27 Sep 2019 02:13:31 -0700 (PDT), Madhavan Bomidi wrote:
>
> Can someone help me to make python code (with some arbitrary data) for
> the angular distribution rose diagram as shown in figure 7 in the
> paper accessible through the web-link:
>
> https://www.nat-hazards-earth-syst-sci.net/17/1425/2017/nhess-17-1425-2017.pdf

Googling "matplotlib rose diagram" (without the quotation marks)
produced some promising results.  This one even has sample code:

   http://geologyandpython.com/structural_geology.html

I'm no graphics expert, but Matplotlib generally does the job for me.

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Re: Xlabel and ylabel are not shown

[Peter Pearson]

On Sat, 17 Aug 2019 10:58:43 -0700 (PDT), Amirreza Heidari wrote:
> plt.figure(1)
> plt.plot(history.history["loss"], "b", label="Mean Square Error of training")
> plt.plot(history.history["val_loss"], "g", label="Mean Square Error [snip]
> plt.legend()
> plt.xlabel("Epoche")
> plt.ylabel("Mean Square Error")
> plt.xlim(0,200)
> plt.show()
> plt.savefig(r"C:\Users\aheidari\Dropbox\Dissertation\primary hot [snip]

It works for me (using simple, fake data points, of course).  Perhaps
you could tell us which versions of Python and matplotlib you're using?

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Re: Creating time stamps

[Peter Pearson]

On Mon, 22 Jul 2019 16:25:32 -0500, Michael F. Stemper wrote:
> On 22/07/2019 15.58, Chris Angelico wrote:
>> On Tue, Jul 23, 2019 at 6:34 AM Michael F. Stemper
>>  wrote:
>>>
[snip]
>>>   from datetime import datetime
>>>   from time import strftime
>>>   timestamp = datetime.now().strftime( "%Y-%m-%d %H:%M" )
[snip]
>> 
>> What's the second import doing though? You never use strftime.
>
> Cleaned my contacts, cleaned my readers. Still see strftime() in the
> third line. Tried to run the code without the second line. It ran
> without complaint.
>
> Apparently, the strftime() in that last line is not the one that I
> explicitly imported, but a method of datetime.now(). Did I get that
> right?

Yes, you got that right.  The statement datetime.now().strftime("...")
says that datetime.now will return an object that has a method
named strftime, and calling that method is the next thing to be done.
Other things that happen to be lying around named strftime just have
no part in the conversation.

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Re: How to sort the files based on the date?

[Peter Pearson]

On Mon, 15 Jul 2019 09:20:51 +0200, Peter Otten <__pete...@web.de> wrote:
> Madhavan Bomidi wrote:
>
[snip]
>> 
>> 3RIMG_01APR2018_0514_L2G_AOD.h5
>> 3RIMG_01APR2018_0544_L2G_AOD.h5
>> 3RIMG_01APR2018_0644_L2G_AOD.h5
>> 3RIMG_01APR2018_0714_L2G_AOD.h5
>> 3RIMG_01APR2018_0744_L2G_AOD.h5
[snip]
>> 
>> Can anyone suggest me how I can sort theses files in increasing order of
>> the date on the file name?
>
> Use a key function
>
> filenames = sorted(filename, key=get_datetime)
>
> get_datetime should extract date/time from the filename into a datetime 
> object. The names will then be ordered according to the datetimes' values:
>
> import glob
> import datetime
>
> def get_datetime(filename):
> parts = filename.split("_")
> return datetime.datetime.strptime(parts[1] + parts[2], "%d%b%Y%H%M")
>
> filenames = sorted(glob.glob('3RIMG_*.h5'), key=get_datetime)
>
> for fn in filenames:
> print(fn)


Gorgeous.  This is the best newsgroup ever.

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Re: Seeking help regarding Python code

[Peter Pearson]

On Thu, 11 Jul 2019 06:54:21 +0100, Debasree Banerjee wrote:
>
> I have a dataset like this:
>
> RecTime
>
> NO2_RAW
>
> NO2
>
> LAQN_NO2
>
> 10980
>
> 06/6/19 01:45
>
> 17.9544
[snip]
>
> Can someone please help?

Your question might appear intelligibly on the mailing list (I can't tell),
but it is mangled into unintelligibility on the newsgroup.  My guess
is that instead of double-spaced mixed-type data fields, you intended
to present an input table like this:

RecTime NO2_RAW NO2 LAQN_NO2
10980   06/6/19 01:45   17.9544 53.4626 17.7
10981   06/6/19 01:45   17.9444 53.4434 17.7
10982   06/6/19 01:45   17.9211 53.3988 17.7

I really can't tell what you want the output to look like.

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Re: finding a component in a list of pairs

[Peter Pearson]

[snip]
> print( dict( pairs ).get( 'sun', '(unknown)' ))

You probably know this, but . . . just in case . . .

If you're doing this many times, you'll want to construct the dict
just once and then make many references to the dict, rather than
re-constructing the dict every time you want to look up an element.

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Re: finding a component in a list of pairs

[Peter Pearson]

On 22 Jun 2019 13:24:38 GMT, Stefan Ram  wrote:
[snip]
>
> print( next( ( pair for pair in pairs if pair[ 0 ]== 'sun' ), 
>  ( 0, '(unbekannt)' ))[ 1 ])
> print( next( itertools.dropwhile( lambda pair: pair[ 0 ]!= 'sun', pairs ))
>  [ 1 ])
[snip]
>
>   The last two lines of the program show two different
>   approaches to search for the translation of »sun«.
>
>   Which approach is better? Or, do you have yet a better idea
>   about how to find the translation of »sun« in »pairs«?

Are you allowed to use a dict?

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Re: Why am a getting wrong prediction when combining two list of samples, which individually gives correct prediction?

[Peter Pearson]

On Wed, 12 Jun 2019 04:12:34 -0700 (PDT), Rishika Sen wrote:

> So I am coding in Python. I have to set of samples. Set1 contains
> samples of class A and the other set, Set2 contains samples of class
> B. When I am predicting set1 and set2 individually, the classification
> is perfect. Now when I am merging the two sets for prediction into one
> set, the prediction gives the wrong result for the samples in Set2,
> i.e., predicting the samples of set 2 to be in class A. However,
> samples belonging to Set1 are predicted to be in class A in the merged
> set. Why is this happening?
>
> model.add(Dense(newshape[1]+1, activation='relu', input_shape=(newshape[1],)))
> model.add(Dropout(0.5))
> model.add(Dense(500, activation='relu'))
> model.add(Dropout(0.5))
> model.add(Dense(250, activation='relu'))
> model.add(Dropout(0.5))
> model.add(Dense(100, activation='relu'))
> model.add(Dropout(0.5))
> model.add(Dense(50, activation='relu'))
> model.add(Dropout(0.5))
> model.add(Dense(1, activation='sigmoid'))
> model.compile(loss='binary_crossentropy',
>   optimizer='adam',
>   metrics=['binary_accuracy'])
> model.fit(X_train, y_train,validation_data=(X_test, y_test),
>  validation_split=0.2, epochs=500, batch_size=25, verbose=0)

This is really a question about some model-fitting package that you're
using, not about Python.  And you don't even tell us which model-fitting
package it is.  Please share more information.

Are you expecting that any model-fitting process that works individually
on Set1 and Set2 must work on the union of the two sets?  'Cause I don't
think it works that way.

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Re: Read the table data from PDF files in Python

[Peter Pearson]

On Wed, 24 Apr 2019 02:36:27 -0700 (PDT), mrawat...@gmail.com wrote:
> Hello,
> Anyone knows how to fetch the data from PDF file having tables with
> other text in Python. Need to fetch some cell values based on
> condition from that table.

You might find pdftotext useful.

The command . . .

  pdftotext -layout somefile.pdf

produces a file named somefile.txt.

This will be completely useless if the original PDF is just
a PDF wrapper around an image.  That's what document scanners
tend to produce.

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Re: Trying to read in data for a file to a python application

[Peter Pearson]

On Tue, 26 Feb 2019 15:51:38 +, Paul Sutton  wrote:
> Hi
>
> I have been trying to write a small application that is essentially user
> information application.
>
> https://raw.githubusercontent.com/zleap/AboutMe/master/Aboutme.py
>
> So far I have managed to write the data generated to a file, what I want
> to do now, is read this data back in when the user opens the program.
>
[snip]
>
> So far the GUI window appears but no widgets. So something is clearly
> getting stalled.
>
> To begin with If I can read the text in, and just display in the console
> this is a start, I can then see if I can figure out how to take that and
> insert the data in to the right places.

I'd suggest writing a terminal-based, non-GUI program to read
your data file and do something simple with it like displaying
it on the terminal.  The strategy is to tackle your problem (reading
back the data) in the simplest context possible.

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Re: JPEGImage() hangs

[Peter Pearson]

On Fri, 28 Sep 2018 15:01:41 +0100, Chris Green  wrote:
> Chris Green  wrote:
>> Brian Oney  wrote:
>> > Could you please try another tool like `convert'? E.g.
>> > 
>> > $ convert 102_PANA/P1020466.JPG test.png
>> > 
>> > 
>> > What does that say?
>> 
>> Well, after having returned home with the laptop where this was
>> failing and doing exactly the same thing again, it now works.  However
>> it did take several seconds before the >>> prompt appeared.
>> 
>> The problem seems to be intermittent as I'm calling the function while
>> importing images from a camera SD card and, sometimes, the import
>> hangs but most times it works OK.
>> 
>> I'll see if I can see anything common to when it hangs.
>> 
> ... and the result is that it now hangs several images later in the
> sequence!  It's almost as if some resource is running out.
>
> If I try convert on the 'problem' image it too hangs absolutely
> solidly needing a 'kill -9'.
>
> After some experimentation  OK, it's some sort of file
> accessibility problem between the SD card and the computer:-
>
>   Running 'convert 102_PANA/P1020493.JPG /tmp/xyz.png' hangs
>
>   So 'kill -9' the convert
>
>   Run 'cp 102_PANA/P1020493.JPG /tmp/fred' takes several seconds but returns
[snip]

If copying that particular file takes longer than copying other files,
I'd start to suspect that it's stored in a failing spot in memory.  Is
102_PANA/P1020493.JPG being read from a camera's flash memory?  Does
"convert" hang on /tmp/fred? Does 102_PANA/P1020493.JPG have an unusual
size?  Can you use smartctl to ask the storage device if it's
encountering many errors?

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Re: GUI, Python2.7- how to build a loop with a button + textbox

[Peter Pearson]

On Tue, 11 Sep 2018 19:51:01 -0700 (PDT), alon.naj...@gmail.com wrote:
> hi,
>
> on python 2.7 how do I build a loop with a button + textbox?
>
> for example:
>
> I want the user to enter is name and then press "ok" button, I want
> his name to be printed 5 times.

Tested on Python 3.5.3:

import browsergui as bg

def button_clicked():
for i in range(5):
print(text_field.value)
   
text_field = bg.TextField()
bg.GUI(text_field, bg.Button("OK", callback=button_clicked)).run(quiet=True)

If you don't have browsergui, "pip install browsergui".

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Re: Python Probability

[Peter Pearson]

On Tue, 11 Sep 2018 20:54:23 +0200 (CEST), Bat erdene endzis wrote:
[snip]
> def dice():
> attacker_dice=[random.randint(1,6) for _ in range(3)]
> defender_dice=[random.randint(1,6) for _ in range(2)]
> a=max(attacker_dice)
> b=max(defender_dice)
> for i in range(1000):
> F=0
> S=0
> T=0
> if a>b:
> F+=1
> if a==b:
> S+=1
> else:
> T+=1

Do you really want to set F, S, and T back to zero on each pass through
that loop?

Presumably you want to remove a from attacker_dice and b from
defender_dicce and repeat the comparison with the new maxes.

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Re: perplexing error

[Peter Pearson]

On 8 Sep 2018 19:10:09 GMT, Stefan Ram  wrote:
> Peter Pearson  writes:
>>On 8 Sep 2018 17:25:52 GMT, Stefan Ram  wrote:
>>>In such cases, I do:
>>>print( 'at position 1' )
>>This approach is especially valuable when it turns out that
>>the file you're editing is not the file being included.
>
>   I am not sure whether this is taken to be literally or as
>   being sarcastic.
[snip]

No sarcasm intended.  I've made the editing-wrong-file goof many times.

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Re: perplexing error

[Peter Pearson]

On 8 Sep 2018 17:25:52 GMT, Stefan Ram  wrote:
> Sharan Basappa  writes:
>> 66 # get the label for each log
>> 67 data_df['label'] = (data_df['label'] != '-').astype(int)
>>---> 68 #logger.debug("data frame %s \n", data_df)
>> 69 logger.debug("\n")
>> 70 raw_data = data_df[['label','seconds_since']].as_matrix()
>>AttributeError: 'str' object has no attribute 'raw_data' 
>>If you notice, line 68 is commented.
>>I am not sure what I am doing wrong.
>
>   In such cases, I do:
>
> print( 'at position 1' )
> data_df['label'] = (data_df['label'] != '-').astype(int)
> print( 'at position 2' )
> raw_data = data_df[['label','seconds_since']].as_matrix()
> print( 'at position 3' )
>
>   . If the last text printed is "at position 1", I will then
>   split even more:
>
> print( 'at position 1' )
> tmp = (data_df['label'] != '-').astype(int)
> print( 'at position 1a' )
> data_df['label'] = tmp
> print( 'at position 2' )
> raw_data = data_df[['label','seconds_since']].as_matrix()
> print( 'at position 3' )
>
>   and so on until the cause is reduced to the smallest
>   possible unit of code.

This approach is especially valuable when it turns out that
the file you're editing is not the file being included.

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Re: Pass a list of values as options to 3 dropdown menus

[Peter Pearson]

On Sun, 2 Sep 2018 13:40:18 -0700 (PDT), Nick Berg wrote:
> how can i be able to store a list of values to drop-down menu and then
> grab the value that the user selects?
>
> **
> name = month = year = ''
>
> # populate names, months, years
> names.add( '' )
> months = ( '==', 'îÖî±î½î¿ïàî¬ïüî1î¿ ...
> years  = ( '=', 2010, 2011, 2012, 2 ...
>
>
> pdata = pdata + '''
> îòï î1î»îµîºïäî1îºîR
îæî½î±î¶îRïäî·ïâî·: 
>
> 
>  %s 
> 
>
> 
>  %s 
> 
>
> 
>  %s 
> 
> 
> 
> ''' % ( url_for( 'seek', name=name, month=month, year=year ), name, name,
month, month, year, year )
> **

I can't tell whether this is an HTML question or a Python question. If you can
reduce it to a Python question, perhaps I can help.

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Re: Pass a list of values as options to 3 dropdown menus

[Peter Pearson]

On Tue, 4 Sep 2018 10:13:07 -0700 (PDT), Nick Berg wrote:
[snip]
>
> May i ask how you managed to send an email with a domain
> nowhere.invalid ? I would like to do the same.

I don't post by sending email, I post by using a news client (slrn),
which interacts with the Usenet system
(en.wikipedia.org/wiki/News_client), a largely decentralized
news-sharing system that dates from the 1970's (I think) and works
through the use of a somewhat casual network of servers that circulate
messages among themselves.  In contrast (if I read your headers right),
you read and post by using Google Groups, a newfangled invention that
we fossils from the days of gods and giants consider lame and hostile
to efficient organization, and we suspect that prolonged use
results in an inability to hoist one's trousers above one's buttocks
and a tendency to use interrogatory intonation on declarative sentences.

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Re: Pass a list of values as options to 3 dropdown menus

[Peter Pearson]

On Sun, 2 Sep 2018 13:40:18 -0700 (PDT), Nick Berg wrote:
> how can i be able to store a list of values to drop-down menu and then
> grab the value that the user selects?
>
> **
> name = month = year = ''
>
> # populate names, months, years
> names.add( '' )
> months = ( '==', 'Ιανουάριο ...
> years  = ( '=', 2010, 2011, 2012, 2 ...
>
>
> pdata = pdata + '''
> Επιλεκτική Αναζήτηση: 
>
> 
>  %s 
> 
>
> 
>  %s 
> 
>
> 
>  %s 
> 
>  value="<Αναζήτηση>">
> 
> ''' % ( url_for( 'seek', name=name, month=month, year=year ), name, name, 
> month, month, year, year )
> **

I can't tell whether this is an HTML question or a Python question.
If you can reduce it to a Python question, perhaps I can help.

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Re: Help Needed : script weird result.

[Peter Pearson]

On Sat, 1 Sep 2018 10:11:59 -0700 (PDT), moha...@gmail.com wrote:
> All,
>
> I m trying to run this small script to find the lowest of the given
> array of numbers. The script works fine for various combination of
> inputs but fails in a weird way for a particular set of inputs, can
> anyone point the mistake in the script and the behavior.
>
> Script
>
> x = input ("Enter the numbers separated by space and press ENTER :")
> x = x.split(" ")
>
> def checkmin(arr):
> lowest = arr[0]
> for count in range(0,len(arr),1):
> if arr[count] < lowest :
> lowest = arr[count]
> else :
> pass
> print (lowest)
> return lowest
>
> minimum = checkmin(x)
> print ("Lowest : {0}".format (minimum))
>
>
> Weird output is as below.
>
>== RESTART: C:\Users\mohan\Desktop\temp.py ==
> Enter the numbers separated by space and press ENTER :5 90 63 82 59 24
> 5
> 5
> 5
> 5
> 5
> 24
> Lowest : 24

Assuming this is homework, here's a hint:
Instead of "5 90 63 82 59 24", feed it "2 ", or "1 09" 
or "1 2 3 ." (yes, ".").

As a stylistic matter, looping over an array's indices is more
cumbersome than looping over the elements of the array ("for x in arr:"),
unless you actually need the index for something, which you don't.
Also, two of the three arguments you pass to range can be omitted.

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Re: Verifying the integrity/lineage of a file

[Peter Pearson]

On Fri, 31 Aug 2018 12:51:58 -0600, Malcolm Greene  wrote:
> Thanks for the replies! I'm going to investigate the use of
> python-gnupg which is a Python wrapper for the GPG command line
> utility. This library is based on gpg.py written by Andrew Kuchling.
> I'm all ears if f anyone has any alternative recommendations or
> python-gnupg tips to share. BTW: Target clients are running under
> Windows and Linux.

Writing your own crypto software is fraught with peril, and that
includes using existing libraries.  If you don't expect your system
to get serious attention from a competent adversary, then fine, go
ahead.  No ... not even that.  If you're _quite_confident_ that
your system will never get serious attention ... go ahead.  But
if you think your system might someday be attacked by an adversary
who will exploit insufficiently unguessable nonces, or accidental nonce
re-use, or swap-space images of your executing code, or side channels,
or any of the other hundreds of issues that have left the history
of cryptography so entertainingly littered with the bodies of brilliant
aspirants, . . . then use a much-studied, time-tested product.

Don't take my word for it (retired cryptologist), ask any reputable
cryptologist.  Or ask on the sci.crypt newsgroup; they need some
traffic.

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Re: Verifying the integrity/lineage of a file

[Peter Pearson]

On Fri, 31 Aug 2018 08:36:52 -0600, Malcolm Greene  wrote:
> I have use case where I need to distribute binary files to customers and
> want to provide a way for our customers to verify the
> "integrity/lineage" (I know there's a better description, but can't
> think of it) of these files, eg. to give them the confidence that the
> files in question are from me and haven't been altered.
[snip]

This is exactly what digital signatures are for.  GPG is free, and will
serve as well as anything.  Generate a public/private key pair, email
the public key to the customer, and phone the customer to compare key
"fingerprints" to verify that the key hasn't been altered in transit
(very unlikely, but cryptologists are a cautious bunch).

Just using HMAC requires sharing a secret with the customer, which
means that you have to trust the customer not to forge authentications.
A real digital signature avoids this problem by separating the signing
key (your private key) from the verifying key (the public key).

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Re: zpifile.py error - no crc 32 attribute

[Peter Pearson]

On Wed, 22 Aug 2018 13:12:59 +0200, jacob m  wrote:
[snip]
> That's my error:
> "import zipfile
>   File "/home/lib/python3.7/lib/python3.7/zipfile.py", line 19, in 
> crc32 = zlib.crc32
> AttributeError: module 'zlib' has no attribute 'crc32' "
>
> I have no idea what to do with that :/ I use this version of zipfile:
> https://github.com/python/cpython/blob/3.7/Lib/zipfile.py
>
> Somebody knows how to solve it?

zipfile imports zlib and expects zlib to define something called crc32.
On your system, for some reason, the zlib that's being imported doesn't
define anything called crc32.  Is there perhaps a different zlib on
your path, hiding the real zlib?

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Re: curses, ncurses or something else

[Peter Pearson]

On Mon, 23 Jul 2018 23:24:18 +0100, John Pote wrote:
> I recently wrote a command line app to take a stream of numbers, do some 
> signal processing on them and display the results on the console. There 
> may be several output columns of data so a title line is printed first. 
> But the stream of numbers may be several hundred long and the title line 
> disappears of the top on the console.
>
> So I thought it might be quick and easy to do something with curses to 
> keep the title line visable while the numbers roll up the screen. But 
> alas I'm a Windows user and the 'curses' module is not in the Windows 
> standard library for Python.
>
> It occured to me that I could create a simple tkinter class but I 
> haven't tinkered for some time and would have to refresh my knowledge of 
> the API. Just wondered if there was any other simple way I could keep 
> the title line on the console, preferably without having to install 
> another library.

Browsergui is designed to simplify GUI-building by mooching off your web
browser.  I like it.

sudo pip3 install browsergui
python3 -m browsergui.examples

Enjoy!

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Re: What is the pattern for this number set?

[Peter Pearson]

On Wed, 18 Jul 2018 17:16:21 -0400, no@none.invalid  wrote:
[snip]
> Anyone care to figure out the pattern and make a new copy of the
> chart?
>
> https://imgur.com/a/thF6U43

I've only looked at infantry and carrier, but those two seem to be
fairly well approximated by y = a + 1/(b*x + c), for a, b, and c
being chosen individually for infantry and carrier.

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Morning after

[Peter Pearson]

As if in a wake for Guido, grief was grieved, drinks were drunk, voices
were raised, and some furniture was broken.  Now, please, let's resume
being the most civil newsgroup on the net.

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Re: translating foreign data

[Peter Pearson]

On Thu, 21 Jun 2018 10:12:27 -0700, Ethan Furman  wrote:
> I need to translate numeric data in a string format into a binary
> format.  I know there are at least two different methods of
> representing parts less that 1, such as "10.5" and "10,5".  The data
> is encoded using code pages, and can vary depending on the file being
> read (so I can't rely on current locale settings).
>
> I'm sure this is a solved problem, but I'm not finding those
> solutions.  Any pointers?

Do you also have to accommodate the possibility that one thousand
might be written "1,000" or "1.000"?

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Re: write the values of an ordered dictionary into a file

[Peter Pearson]

On Thu, 21 Jun 2018 22:41:48 +0530, Ganesh Pal  wrote:
[snip]
[what I think OP wants:]
>
> *.*
>
> *||STUDENT NAME||STUDENT AGE||MARKS SCORED||PASSED YEAR||FEES PAID||*
>
> *||John||  28   ||  13|| 2018  || 250 ||*
>
>
> Questions:
>
> (1) Below is my partial solution , any comments and suggestions ( I am not
> to get the “||” delimiter correctly, trying it )
>
> #!/usr/bin/python
> # A Python program to write the values of an OderedDict into a file
> # The values should be formatted correctly under its headers
>
> from collections import OrderedDict
>
> tmp = '/tmp/student_record.txt'
> student = [("NAME", "John"),
>("AGE", 28),
>("SCORE", 13),
>("YEAR", 2018),
>("FEE", 250)]
>
> student = OrderedDict(student)
> header_list = ["STUDENT NAME", "STUDENT AGE", "MARKS SCORED", "PASSED YEAR",
> "FEES PAID"]
>
> header_string = '||' + '||'.join(header_list) + '||'
> with open(tmp, 'a') as fd:
>  for item in header_string:
>  fd.write("%s" % (item))
>
>  for value in student.values():
>  fd.write("\n")
>  fd.write("||")
>  fd.write("%s" % (value))
>
> *output:*
> *root@X1:/Play_ground/SPECIAL_TYPES# cat /tmp/student_record.txt*
> *||STUDENT NAME||STUDENT AGE||MARKS SCORED||PASSED YEAR||FEES PAID||*
> *||John*
> *||28*
> *||13*
> *||2018*
[snip]

You don't say which aspects of this output you find unsatisfactory and
want help with, but . . .

 - You're writing "\n" in front of every *field*, when you only want to
   write it in front of every line; and

 - To make the columns line up right, you'll want to specify the widths
   of the character strings being written, e.g., using "%10s" in place
   of "%s".

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Re: Understanding memory location of Python variables

[Peter Pearson]

On Sat, 16 Jun 2018 09:38:07 -0700 (PDT), ip.b...@gmail.com wrote:
> Hi everyone,
>
> I'm intrigued by the output of the following code, which was totally
> contrary to my expectations. Can someone tell me what is happening?
>
 myName = "Kevin"
 id(myName)
> 47406848
 id(myName[0])
> 36308576
 id(myName[1])
> 2476000

You left out one of the more interesting (and possibly informative)
angles:

>>> myName = "Kevin"
>>> x0 = myName[0]
>>> x1 = myName[1]
>>> x01 = myName[0:2]
>>> y0 = "K"
>>> y1 = "e"
>>> y01 = "Ke"
>>> id(x0) == id(y0)
True
>>> id(x1) == id(y1)
True
>>> id(x01) == id(y01)
False
>>> x01 == y01
True

myName[0] is the string "K", and this Python implementation happens
to economize by having only a single object "K".  This economy measure
probably only applies to single-character strings.

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Re: What data types does matplotlib pyplot take?

[Peter Pearson]

On Wed, 13 Jun 2018 12:53:57 -0400, C W  wrote:
> Hi everyone,
>
> I'm curious what data types pyplot takes. It seems that it can take numpy
> series, pandas series, and possibly pandas dataframe? How many people data
> types are out there? Is that true for all functions in like hist(), bar(),
> line(), etc?

I regret that this might seem less than helpful, but someone
should point out that an enumeration beginning "This package
works with the following data types" would be antithetical to
Python's "duck-typing" philosophy.  The important thing is not
an object's type, but whether the object has the attributes and
methods required.

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Re: Sorting NaNs

[Peter Pearson]

On Fri, 8 Jun 2018 02:15:02 + (UTC), Steven D'Aprano wrote:
> On Thu, 07 Jun 2018 20:43:10 +0000, Peter Pearson wrote:
[snip]
>> 
>> But gosh, if there are only 2**32 different "random" floats, then you'd
>> have about a 50% chance of finding a collision among any set of 2**16
>> samples.  Is that really tolerable?
>
> Why wouldn't it be? It would be shocking if a sufficiently large sequence 
> of numbers contained no collisions at all: that would imply the values 
> were very much NON random.

[snip]

> . . . I understand that Python's Mersenne Twister implementation 
> is based on 64-bit ints.

OK, I'll relax, particularly since Michael Lamparski's experiment
strongly indicates that random floats are drawn from a population much
larger than 2**16.

You're completely correct, of course, in noting that an absence of
collisions would condemn the random-number generator just as badly
as an excess.  What bothered me was my feeling that a "reasonable
observer" would expect the random-float population to be much larger
than 2**32, and the probably-collision-free sample size to be accordingly
much larger than 2**16, which is, after all, small enough to appear
in many applications.

Exactly what the "reasonable observer" would expect that population to
be, I don't know.  To a mathematician, there's zero chance of collision
in any finite sample of real numbers, or even just rational numbers; but
I don't think anybody would expect that from a computer.  When I picture
the diligent software engineer asking himself, "Wait, how large can I
make this sample before I'll start seeing collisions," I imagine his
first guess is going to be the size of a float's mantissa.

What applications would have to worry about colliding floats?  I
don't know.  I'm coming from cryptology, where worrying about such
things becomes a reflex.

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Re: Sorting NaNs

[Peter Pearson]

On Thu, 07 Jun 2018 19:02:42 +1200, Gregory Ewing wrote:
> Steven D'Aprano wrote:
>> But if it were (let's say) 1 ULP greater or less 
>> than one half, would we even know?
>
> In practice it's probably somewhat bigger than 1 ULP.
> A typical PRNG will first generate a 32-bit integer and
> then map it to a float, giving a resolution coarser than
> the 52 bits of an IEEE double.
>
> But even then, the probability of getting exactly 0.5
> is only 1/2^32, which you're not likely to notice.

But gosh, if there are only 2**32 different "random" floats, then
you'd have about a 50% chance of finding a collision among any
set of 2**16 samples.  Is that really tolerable?
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Re: Stefan's headers [was:Names and identifiers]

[Peter Pearson]

On Thu, 7 Jun 2018 01:23:31 + (UTC), Steven D'Aprano wrote:
> Disclaimer: Ido not see Stefan's original post. I recall that he has set 
> some sort of header on his posts which means they are not processed by 
> Gmane, but unfortunately I no longer have any of his posts in my cache 
> where I can check.
>
> If anyone else is getting Stefan's posts, can you inspect the full 
> headers and see if there is a relevant header?

Here's the full header, as received by slrn from news.individual.net:

Path: uni-berlin.de!not-for-mail
From: r...@zedat.fu-berlin.de (Stefan Ram)
Newsgroups: comp.lang.python
Subject: Names and identifiers
Date: 6 Jun 2018 18:37:46 GMT
Organization: Stefan Ram
Lines: 26
Expires: 1 Aug 2018 11:59:58 GMT
Message-ID: 
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-Trace: news.uni-berlin.de y/fWNNOsUiR8l3NiIdt8QQKv4EmIpqY+4EFRjM4L9WcmK0
X-Copyright: (C) Copyright 2018 Stefan Ram. All rights reserved. Distribution 
through any means
  other than regular usenet channels is forbidden. It is forbidden to publish 
this article in the
  Web, to change URIs of this article into links,and to transfer the 
body without this
  notice, but quotationsof parts in other Usenet posts are allowed.
X-No-Archive: Yes
Archive: no
X-No-Archive-Readme: "X-No-Archive" is only set, because this prevents some 
services to mirror the
  article via the web (HTTP). But Stefan Ram hereby allows to keep this article 
within a Usenet
  archive serverwith only NNTP access without any time limitation.
X-No-Html: yes
Content-Language: en
Xref: uni-berlin.de comp.lang.python:794657
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Re: Attachments (was: How can an int be '+' with a tuple?)

[Peter Pearson]

On Sun, 3 Jun 2018 20:20:32 +0200, Peter J. Holzer  wrote:
[snip]
> On 2018-06-03 13:57:26 +1000, Ben Finney wrote:
>> (For good reasons, attachments are dropped when messages are distributed
>> on the forum.)
>
> By "the forum" you mean Gmane? (I got the attachment over the mailing
> list)

Comp.lang.python is a usenet newsgroup, also accessible through a mailing
list (and, I think, a web interface).  NNTP, the Network News Transfer
Protocol, does not provide for attachments.

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Re: Indented multi-line strings

[Peter Pearson]

On Fri, 1 Jun 2018 15:57:58 +0100, Paul Moore  wrote:
> On 1 June 2018 at 15:36, Dan Strohl via Python-list
> wrote:
>> So... how does one go about suggesting changes to the built in types?
[snip]
>
> Why does this need to be a string method? Why can't it be a standalone
> function?

Yes, please, let's content ourselves with a standalone function.

Adding features to a language imposes costs in several ways, including
hindering newcomers and making code version-dependent.  To full-time
Python developers, these costs appear small, because they are amortized
over a lot of Python activity; but they are encumbrances to the spread
and casual use of the language.  It seems as if the destiny of every
language is to be adorned by its enthusiasts with so many arcane and
specialized optimizations -- every one an obvious improvement -- that
the world's interest drifts to something newer and cleaner.
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Re: seeking deeper (language theory) reason behind Python design choice

[Peter Pearson]

On Wed, 09 May 2018 12:51:15 -0700, Paul Rubin wrote:
> Dennis Lee Bieber  writes:
>>  Yes, code reviews may catch such errors... and later, when the
>> summary of errors is analyzed for suggestions on how to reduce them --
>> the odds are good that "assignment expressions" will be banned in the
>> style documents for that language at the company.
>
> I don't think I've worked on any C programs with that style restriction
> and I can't think of any times when I found that type of bug in deployed
> code.  I've made the error once or twice while coding, but caught it
> right away during inspection or testing.  Banning it seems
> counterproductive.  I could imagine having it flagged by a compiler
> warning that can be locally disabled by a pragma.  

Interestingly, the problem is broader than inadvertently making the
mistake yourself; it includes catching deliberate misdirection by
others.  In the famous "Linux Backdoor Attempt of 2003"
(https://freedom-to-tinker.com/2013/10/09/the-linux-backdoor-attempt-of-2003/),
somebody who I think never got caught introduced these lines
into the code for the wait4 function:

if ((options == (__WCLONE|__WALL)) && (current->uid = 0))
retval = -EINVAL;

Setting the user ID to zero confers root privileges.

- Peter
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Re: Where has the practice of sending screen shots as source code come from?

[Peter Pearson]

On Mon, 29 Jan 2018 14:46:59 -0500, Dennis Lee Bieber wrote:
> On 29 Jan 2018 17:26:32 GMT, Peter Pearson <pkpearson@nowhere.invalid>
> declaimed the following:
>
>>
>>In 1964, the IBM exhibit at the World's Fair in New York demonstrated
>>a system that read dates that visitors wrote by hand.  (You were
>>supposed to write your date of birth, and the system then printed
>>the New York Times's headline for that date.)
>
>   Was it somehow scanning dates from paper or cards, or was it using some
> sort of touch sensor input (pressure tablet, or a pen in a harness with
> position sensors).
>
>   The first would be OCR proper, while the second is what many PDAs (and
> some tablets) rely upon. The second provides actually stroke vector
> information on how the characters are formed, which is more reliable than
> just seeing pixel transitions and trying to match characters to them.

We wrote our dates of birth on paper or punch cards (I forget which)
with an ordinary pen.  We handed the papers (or cards) to someone who
fed them into a machine, which printed slips of paper that were handed
to us as we exited.  According to the promotional displays, our writing
was examined optically; one poster showed a scan path that resembled
an extremely prolate cycloid following along the handwritten line.

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Re: checksum problem

[Peter Pearson]

On Tue, 30 Jan 2018 11:24:07 +0100, jak  wrote:
> Hello everybody,
> I'm using python 2.7.14 and calculating the checksum with the sha1 
> algorithm and this happens: the checksum is wrong until I read the whole 
> file in one shot. Here is a test program:
>
> import hashlib
>
> def Checksum(fname, blocks):
>  m = hashlib.sha1()
>  print "sha1 block size: " + str(m.block_size * blocks)
>  with open(fname, "rb") as fh:
>  for data in fh.read(m.block_size * blocks):
>  m.update(data)
>  return m.hexdigest()
>
> def main():
>  for b in range(10, 260, 10):
>  print str(b) + ': ' + 
> Checksum("d:/upload_688df390ea0bd728fdbeb8972ae5f7be.zip", b)
>
> if __name__ == '__main__':
>  main()
>
> and this is the result output:
>
> sha1 block size: 640
> 10: bf09de3479b2861695fb8b7cb18133729ef00205
> sha1 block size: 1280
> 20: 71a5499e4034fdcf0eb0c5d960c8765a8b1f032d
> .
> .
> .
> sha1 block size: 12160
> 190: 956d017b7ed734a7b4bfdb02519662830dab4fbe
> sha1 block size: 12800
> 200: 1b2febe05b70f58350cbb87df67024ace43b76e5
> sha1 block size: 13440
> 210: 93832713edb40cf4216bbfec3c659842fbec6ae4
> sha1 block size: 14080
> 220: 93832713edb40cf4216bbfec3c659842fbec6ae4
> .
> .
> .
>
> the file size is 13038 bytes and its checksum is 
> 93832713edb40cf4216bbfec3c659842fbec6ae4
>
> Why do I get these results? What am I doing wrong?
>
> Thanks to everyone in advance.

I believe your "for data in fh.read" loop just reads the first block of
the file and loops over the bytes in that block (calling m.update once
for each byte, probably the least efficient approach imaginable),
omitting the remainder of the file.  That's why you start getting the
right answer when the first block is big enough to encompass the whole
file.

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Re: Where has the practice of sending screen shots as source code come from?

[Peter Pearson]

On Sun, 28 Jan 2018 20:24:55 -0800, Dan Stromberg  wrote:
[snip]
>
> Is it really true that OCR appeared long before Neural Networks
> (NN's)?  I first heard of NN's in the 80's, but OCR more like the
> 90's.

In 1964, the IBM exhibit at the World's Fair in New York demonstrated
a system that read dates that visitors wrote by hand.  (You were
supposed to write your date of birth, and the system then printed
the New York Times's headline for that date.)

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Re: Compression of random binary data

[Peter Pearson]

On Sat, 27 Jan 2018 21:26:06 -0800 (PST), pendrysamm...@gmail.com wrote:
> If it is then show him this
>
> 387,420,489
>=
> 00110011 00111000 00110111 00101100 00110100 00110010 0011 0 ...

To save the casual reader a moment of disorientation, the
above binary string is just the ASCII representation of the
text string "387,420,489".

> 9^9 = ⬇️ (^ = to the power of)
>= 387,420,489
>
> But
>
> 9^9
>=
> 00111001 0100 00111001

Similarly, this is the ASCII representation of "9^9".  Our
self-confessedly intermittently sober correspondent appears to have
discovered the backside of the principle that a short text expression
can generate a large number.

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Re: RegExp - please help me!

[Peter Pearson]

On Tue, 26 Dec 2017 05:14:55 -0800 (PST), szykc...@gmail.com wrote:
[snip]
> So: I develop regexp which to my mind should work, but it doesn't and
> I don't know why. The broken regexp is like this: 
> struct (.+)\s*{\s*(.+)\s*};
[snip]

You'll probably get better help faster if you can present your problem
as a couple lines of code, and ask "Why does this print XXX, when I'm
expecting it to print YYY?"  (Sorry I'm not smart enough to give you
an answer to your actual question.)

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Re: Python bug report

[Peter Pearson]

On Thu, 21 Dec 2017 23:54:17 +0100, Ranya  wrote:
> Hi,
> Am trying to use clr.AddReference and clr.AddReferenceToFile, but
> python(2.7) keeps making this error:
>
> Traceback (most recent call last):
>   File "", line 1, in 
> clr.AddReference("UnityEngine")AttributeError: 'module' object has
> no attribute 'AddReference'
>
> How can I fix this?
> Thanks in advance.

What is clr?  Whatever it is, it doesn't have the AddReference
attribute that you seem to be expecting.

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Re: Repeated Names (Repeated Names)

[Peter Pearson]

On Sat, 16 Dec 2017 12:56:07 +1300, Gregory Ewing wrote:
> Anyone else now getting duplicate posts with the sender's
> name repeated in parentheses?

Yes.  Both of the posts on this thread appear twice, once
with and once without the parenthesized name.  In each pair,
the Date field differed by one second, once in each direction.

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Re: Artificial creating of [Lists], is it possible? the best way...

[Peter Pearson]

On Thu, 16 Nov 2017 10:47:53 -0800 (PST), jakub.raj...@gmail.com wrote:
> Hello, im working on school project, its deck game Sorry!
> I need to create specific lists:
> My idea is about to using for
> For i in range (n):
>i=[]

This will create n different empty lists, in succession, and
discard all but the last one, which will be bound to the name "i".

> I know, that there is no possibility to make it from number, but i
> havent idea, how to reach my wants Li/L"i"/L(i), how to make possible
> for lists?

You'll find that the people on this newsgroup are very helpful, but
they might (like me) be unable to discern what you're asking.


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Re: Python Mailing list moderators

[Peter Pearson]

On Sun, 5 Nov 2017 17:28:05 -0500, Terry Reedy  wrote:
> On 11/5/2017 4:14 PM, Cameron Simpson wrote:
>> On 05Nov2017 13:09, Στέφανος Σωφρονίου  
>> wrote:
>>> Folks,
>>> More and more nonsense are coming in and I find it really difficult to 
>>> follow any new post that may come and I have to either search for 
>>> specific content or scroll down until I hit it by accident.
>>>
>>> Can we do something about it?
>>> It's getting really frustrating :/
>> 
>> It seems from the headers on your message that you're actually using the 
>> comp.lang.python newsgroup and not the mailing list. The newsgroup is 
>> completed unmoderated.  The mailing list is far less noisy.
>> 
>> Go here:
>> 
>>   https://mail.python.org/mailman/listinfo/python-list
>> 
>> and subscribe, and see if things seem better than the newsgroup.
> Or point your newsreader to news.gmane.org group 
> gmane.comp.python.general, which mirrors python-list.
[snip]

Or use a newsgroup reader that can be easily taught to ignore certain
subjects or posters.  Or buy your newsgroup service from a provider that
does some filtering.  I use slrn to read news from news.individual.net,
and see only a handful of spam posts on a typical day.

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Re: Compression of random binary data

[Peter Pearson]

On Thu, 26 Oct 2017 19:26:11 -0600, Ian Kelly  wrote:
>
> . . . Shannon entropy is correctly calculated for a data source,
> not an individual message . . .

Thank you; I was about to make the same observation.  When
people talk about the entropy of a particular message, you
can bet they're headed for confusion.

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Re: Compression of random binary data

[Peter Pearson]

On Tue, 24 Oct 2017 14:51:37 +1100, Steve D'Aprano wrote:
  On Tue, 24 Oct 2017 01:27 pm, danceswithnumb...@gmail.com wrote:
  > Yes! Decode reverse is easy..sorry so excited i could shout.

  Then this should be easy for you:

  http://marknelson.us/2012/10/09/the-random-compression-challenge-turns-ten/

  All you need to do is compress this file:

  
http://marknelson.us/attachments/million-digit-challenge/AMillionRandomDigits.bin

  to less than 415241 bytes, and you can win $100.

Then, on Mon, 23 Oct 2017 21:13:00 -0700 (PDT), danceswithnumbers wrote:
> I did that quite a while ago. 


But 352,954 kb > 415241 bytes, by several orders of magnitude; so
you didn't "do that".  (Or are we using the European decimal point?)

If you're claiming 352,954 *bytes*, not kb, I invite you to explain
why you have not collected Mark Nelson's $100 prize, and untold fame
and glory; failing which, your credibility will evaporate.

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Re: A Good Tutorial on Python Decorators

[Peter Pearson]

On Tue, 27 Jun 2017 16:43:38 +, Andre Müller wrote:
> Peter Pearson <pkpearson@nowhere.invalid> schrieb am Di., 27. Juni 2017 um
> 18:35 Uhr:
>
>> On Tue, 27 Jun 2017 15:10:53 + (UTC), Saurabh Chaturvedi wrote:
>> > https://opensource.google.com/projects/py-decorators-tutorial
>>
>> "No Results found."
>>
> Activate JavaScript, then you can see the content.
> I had the same problem.

(Blushing) Thanks.  Life is getting difficult for us JavaScript paranoids.

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Re: A Good Tutorial on Python Decorators

[Peter Pearson]

On Tue, 27 Jun 2017 15:10:53 + (UTC), Saurabh Chaturvedi wrote:
> https://opensource.google.com/projects/py-decorators-tutorial

"No Results found."

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Re: plot time on X axis

[Peter Pearson]

On Wed, 07 Jun 2017 09:20:25 -0300, jorge.conr...@cptec.inpe.br wrote:
[snip]
> I was an IDL user and I'm using Python. I have several meteorological 
> daily time seriee for several years. Please can someone help me. I would 
> like to plot on X axis only the values o the year.

Is matplotlib allowed?  Example (Python 2.7)(Note that most of
this example is just parsing data, not plotting:):

from matplotlib import pyplot as plt
from datetime import date
import re

dwcd = """
2014-06-01:  82.00% ( 1)  89.50% ( 2)  39.00% ( 1)  0.259
2014-07-01: 100.00% ( 1)  89.00% ( 3)   0.00% ( 1)  0.264
2014-08-01:  79.50% ( 2)  85.50% ( 4)  53.00% ( 1)  0.273
2014-09-01:  85.00% ( 3)  98.00% ( 6)  87.00% ( 3)  0.495
2014-10-01:  86.00% ( 7)  97.00% (10)  82.50% ( 4)  0.553
2014-11-01:  93.50% (10)  98.50% (10)  39.00% ( 6)  0.215
2014-12-01:  97.00% (10) 100.00% (10)  66.50% ( 6)  0.025
2015-01-01:  72.50% (12)  94.00% (11)  39.00% ( 6)  0.025
2015-02-01:  66.00% (12)  88.50% (12)  58.50% ( 8)  0.248
2015-03-01:  79.00% (15)  95.50% (12)  77.00% ( 9)  0.360
2015-04-01:  87.00% (15)  95.50% (12)  68.00% ( 9)  0.039
2015-05-01:  85.50% (18)  90.00% (12)  87.00% ( 9)  0.479
"""

def get_time(r):
r = r.strip()
return date(year=int(r[0:4]),
month=int(r[5:7]),
day=int(r[8:10]))

def get_field(r, field_name):
m = re.match(r"(?P[^:]+): +"
 r"(?P[0-9.]+)% +"
 r"\( *(?P[0-9]+)\) +"
 r"(?P[0-9.]+)% +"
 r"\( *(?P[0-9]+)\) +"
 r"(?P[0-9.]+)% +"
 r"\( *(?P[0-9]+)\) +"
 r"(?P[0-9.]+)", r.strip())
return m.group(field_name)

x = [get_time(r) for r in dwcd.split("\n") if r]
y_a = [float(get_field(r, "value_a")) for r in dwcd.split("\n") if r]
y_b = [float(get_field(r, "value_b")) for r in dwcd.split("\n") if r]
y_c = [float(get_field(r, "value_c")) for r in dwcd.split("\n") if r]

plt.plot(x, y_a, color="red", label="Group A")
plt.plot(x, y_b, color="green", label="Group B")
plt.plot(x, y_c, color="blue", label="Group C")

plt.plot(date(2015,5,20), 101, marker="x", color="white")  

plt.ylabel("Y label")
plt.legend(loc="upper left")
fig = plt.gcf()
fig.autofmt_xdate()
plt.show()


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Re: Bug or intended behavior?

[Peter Pearson]

On Tue, 6 Jun 2017 13:16:00 -0400, Terry Reedy <tjre...@udel.edu> wrote:
> On 6/5/2017 1:01 PM, Peter Pearson wrote:
>> On Fri, 2 Jun 2017 10:17:05 -0700 (PDT), sean.diza...@gmail.com wrote:
>> [snip]
>>>>>> print "foo %s" % 1-2
>>> Traceback (most recent call last):
>>>File "", line 1, in 
>>> TypeError: unsupported operand type(s) for -: 'str' and 'int'
>> 
>> Others have already pointed out that you're assuming the
>> wrong precedence:
>> 
>> Say
>>  "foo %s" % (1-2)
>> not
>>  ("foo %s" % 1) - 2
>> .
>> 
>> Personally I prefer a less compact but more explicit alternative:
>> 
>>  "foo {}".format(1-2)
>
> More compact:
> >>> f'foo {1-2}'
> 'foo -1'

Sarcastic thanks, dude.  Excuse me while I scrub my screen with Clorox.
Or maybe my eyeballs.

More seriously, I thought "format" was the Cool New Thing toward which
all the cool kids were moving.  But here I tried to be cool and put in a
plug for "format", and the hip community seems to be sticking up for
"%".  Can I never get with the times?

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Re: Bug or intended behavior?

[Peter Pearson]

On Tue, 6 Jun 2017 03:10:05 +1000, Chris Angelico wrote:
> On Tue, Jun 6, 2017 at 3:01 AM, Peter Pearson wrote:
[snip]
>> Say
>> "foo %s" % (1-2)
>> not
>> ("foo %s" % 1) - 2
>> .
>>
>> Personally I prefer a less compact but more explicit alternative:
>>
>> "foo {}".format(1-2)
>
> The trouble with the zen of Python is that people now use the word
> "explicit" to mean "code that I like". What is more explicit here? It
> uses a method call instead of an operator, but either way, it's
> completely explicit that you want to populate the placeholders in a
> template string.

I meant simply that when you call "format", you don't have to think
about the precedence of the "%" operator.  Maybe "explicit" isn't
the right word; I just make fewer mistakes when I stick with things
that I use all the time (function calls, in this case).

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Re: How to change variable from list to float

[Peter Pearson]

On Mon, 5 Jun 2017 11:13:54 +0100, Paul Barry wrote:
> On 3 June 2017 at 15:42, Gary Barker  wrote:
>
>> I have searched for a solution to this but have not found a suitable
>> example.
>>
>> The attached code generates this error: Traceback (most recent call last):
>>   File "calcsignal.py", line 7, in 
>> siglevfromexist = 34.8 + existattn
>> TypeError: unsupported operand type(s) for +: 'float' and 'list'
>>
>> How do I convert the list variable (i.e. existattn) to a float?
>>
>> Operating details are:
>> Python 3.4.2
>> Debian 3.16.39-1+deb8u2 (2017-03-07) x86_64 GNU/Linux
>>
>> The following lines are the code in calcsignal.py:
>> azdegpattrev = -47.40715077970316
>> azattndic = {-0.9: [-0.55], -0.5: [-0.46], 3.5: [-21.0], 1.4: [-7.48],
>> 5.5: [-25.0], 0.0: [0.0], 1.9: [-21.0], 13.0: [-38.0], 15.0: [-39.0], 3.6:
>> [-25.0], 20.0: [-39.0], -1.4: [-7.48], 90.0: [-65.0], -0.4: [-0.39], 0.5:
>> [-0.46], 0.1: [-0.04], 1.0: [-1.31], -90.0: [-65.0], 40.0: [-42.0], 180.0:
>> [-65.0], 1.5: [-10.0], -1.2: [-3.69], 0.3: [-0.28], -0.3: [-0.28], 0.2:
>> [-0.15], -0.1: [-0.04], 1.1: [-2.34], -180.0: [-65.0], -0.2: [-0.15], 1.2:
>> [-3.69], -40.0: [-42.0], 0.4: [-0.39], -5.5: [-25.0], -1.5: [-10.0], -20.0:
>> [-39.0], 0.9: [-0.55], -3.5: [-21.0], -1.9: [-21.0], -15.0: [-39.0], -13.0:
>> [-38.0], 1.3: [-5.39], -1.3: [-5.39], -3.6: [-25.0], -1.0: [-1.31], -1.1:
>> [-2.34]}
>> azlist = [-0.9, -0.5, 3.5, 1.4, 5.5, 0.0, 1.9, 13.0, 15.0, 3.6, 20.0,
>> -1.4, 90.0, -0.4, 0.5, 0.1, 1.0, -90.0, 40.0, 180.0, 1.5, -1.2, 0.3, -0.3,
>> 0.2, -0.1, 1.1, -180.0, -0.2, 1.2, -40.0, 0.4, -5.5, -1.5, -20.0, 0.9,
>> -3.5, -1.9, -15.0, -13.0, 1.3, -1.3, -3.6, -1.0, -1.1]
>> azlist = [float(i) for i in azlist]
>> closestaz = min(azlist, key=lambda x: abs(x - azdegpattrev))
>> existattn = azattndic[closestaz]
>> siglevfromexist = 34.8 + existattn
>
> The value in existattn is a single element list.  The single element is a
> float, so just refer to it in your calculation, like so:
>
> siglevfromexist = 34.8 + existattn[0]

But as you do so, remember to wonder why the author of this code
made the elements of azattndic *lists* of values instead of simple
single values.  Then, worry that someday your corrected code, which
uses only the first value of the list, will be handed a list with
several values.  (True, it will execute without exception; but right
now, today, you know that if the list length is not 1, you're
confused.)

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Re: Bug or intended behavior?

[Peter Pearson]

On Fri, 2 Jun 2017 10:17:05 -0700 (PDT), sean.diza...@gmail.com wrote:
[snip]
 print "foo %s" % 1-2
> Traceback (most recent call last):
>   File "", line 1, in 
> TypeError: unsupported operand type(s) for -: 'str' and 'int'

Others have already pointed out that you're assuming the
wrong precedence:

Say
"foo %s" % (1-2)
not
("foo %s" % 1) - 2
.

Personally I prefer a less compact but more explicit alternative:

"foo {}".format(1-2)

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Re: Nested Loop to Generate Triangle

[Peter Pearson]

On Thu, 25 May 2017 09:28:31 -0700 (PDT), Victor Demelo wrote:
> I need the triangle to be in reverse. The assignment requires a nested
> loop to generate a triangle with the user input of how many lines.
>
> Currently, I get answers such as:
> 
> OOO
> OO
> O
>
> When I actually need it to be like this:
> 
>  OOO
>   OO
>O
>
> I just need to get it flipped-over on the other side.
>
> Here is the code I have written, thank you.
>
> base_size = int(input("How many lines? "))
> columns = base_size
>  
> for row in range (base_size) :
>for columns in range (columns) :
>print('O', end='')
>print()

Seems like you're close to a solution.  You just need to print
a certain number of spaces at the beginning of each line, right?

Warning: When you say

for columns in range (columns) :

you're creating a confusing situation with the name "columns":
the original meaning, an integer equal to base_size, is now "shadowed"
by a new meaning.  This sort of thing tends to create trouble.  Besides,
you probably meant to say range(base_size), not range(columns).

I don't know how much you're supposed to know about Python basics,
but have you encountered expressions like 5*"Hello" yet?

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Re: Promiscuous ports under Linux

[Peter Pearson]

On Thu, 4 May 2017 18:04:02 + (UTC), Grant Edwards wrote:
> On 2017-05-04, Peter Pearson <pkpearson@nowhere.invalid> wrote:
>
>> I'm curious to survey all my LAN traffic in various ways, and it seems
>> likely that I will see phenomena that I don't understand, and focussing
>> in on those phenomena is likely to require more flexible filtering
>> than Wireshark can provide.  I expect to leave this process running for
>> maybe 24 hours at a stretch, maybe longer, with real-time alerts when
>> interesting things occur.
>
> You can libpcap (which is what wireshark uses on Linux) to deal with
> the details of capturing the packets and do the analysis in Python.
>
>> Maybe Wireshark can do everything I'll ever need to do, but it seems
>> so complicated, and Python seems so simple . . .
>
> I've been using pylibpcap for yonks, and have no complaints.
>
>   https://sourceforge.net/projects/pylibpcap/
[snip]

Hey, that might do the job.  Thanks!

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Re: Promiscuous ports under Linux

[Peter Pearson]

On Thu, 04 May 2017 10:26:45 GMT, alister <alister.w...@ntlworld.com> wrote:
> On Wed, 03 May 2017 23:57:49 +0000, Peter Pearson wrote:
>
>> Cobbling together a minimalist ethernet-sniffing program, I was hoping
>> to use this simple mechanism for setting the socket to "promiscuous
>> mode" (to see all traffic going past, instead of just traffic addressed
>> to my machine):
>> 
>> s.ioctl(socket.SIO_RCVALL, socket.RCVALL_ON)
>> 
>> Unfortunately, it seems that that mechanism is available under Windows
>> but not under Linux.  Googling around for Linux equivalents, I found
>> only very contorted solutions, and concluded that maybe this lacuna
>> persists because Linux users find it convenient to invoke promiscuous
>> mode from the command line, instead:
>> 
>> $ sudo ip link set eth0 promisc on $ netstat -i# (Verify
>> that the P flag is set.)
>> 
>> This somehow fails: my sniffer continues to see only broadcasts,
>> but if I run dumpcap at the same time, dumpcap captures lots of traffic.
>> 
>> So my question is now two questions:
>> 
>>  . Is it true that going permiscuous under Linux must be somewhat ugly?
>>(It's OK if it is, I'll just copy the ugly code and get moving
>>again.)
>> 
>>  . Why doesn't the command-line "promisc on" work?  (Granted, this is
>>maybe a Linux question.)
>> 
>> Thanks.
>
> any particular reason why you wish to re-invent this particular wheel 
> when wireshark is freely available (& the de-facto tool of choice for 
> most network engineers)

I'm curious to survey all my LAN traffic in various ways, and it seems
likely that I will see phenomena that I don't understand, and focussing
in on those phenomena is likely to require more flexible filtering
than Wireshark can provide.  I expect to leave this process running for
maybe 24 hours at a stretch, maybe longer, with real-time alerts when
interesting things occur.

Maybe Wireshark can do everything I'll ever need to do, but it seems
so complicated, and Python seems so simple . . .

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Re: Promiscuous ports under Linux

[Peter Pearson]

On Wed, 3 May 2017 18:09:08 -0700, Rob Gaddi wrote:
> On 05/03/2017 04:57 PM, Peter Pearson wrote:
>> Cobbling together a minimalist ethernet-sniffing program, I was hoping
>> to use this simple mechanism for setting the socket to "promiscuous
>> mode" (to see all traffic going past, instead of just traffic addressed
>> to my machine):
>>
>> s.ioctl(socket.SIO_RCVALL, socket.RCVALL_ON)
>>
>> Unfortunately, it seems that that mechanism is available under Windows
>> but not under Linux.  Googling around for Linux equivalents, I found
>> only very contorted solutions, and concluded that maybe this lacuna
>> persists because Linux users find it convenient to invoke promiscuous
>> mode from the command line, instead:
>>
>> $ sudo ip link set eth0 promisc on
>> $ netstat -i# (Verify that the P flag is set.)
>>
>> This somehow fails: my sniffer continues to see only broadcasts,
>> but if I run dumpcap at the same time, dumpcap captures lots of traffic.
>>
>> So my question is now two questions:
>>
>>  . Is it true that going permiscuous under Linux must be somewhat ugly?
>>(It's OK if it is, I'll just copy the ugly code and get moving again.)
>>
>>  . Why doesn't the command-line "promisc on" work?  (Granted, this is
>>maybe a Linux question.)
>>
>> Thanks.
>>
>
> Tried running it as root?

Good question; I should have mentioned: Yes:

$ sudo python3 sniff_survey.py


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