Re: [Tutor] Using xml.etree
Hello again. So, any xml.etree experts out there who might have missed this over the weekend? Thanks in advance! Chris ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Using xml.etree
On 19/09/2011 10:46, lists wrote: Hello again. So, any xml.etree experts out there who might have missed this over the weekend? Not me, I'm afraid, but might I suggest that you ask on the mail Python list: http://mail.python.org/mailman/listinfo/python-list There's nothing wrong with asking here, but since this question is more specific to a particular library than to Python-the-language you're more likely to find people familiar with the package (including its maintainer in fact...) TJG ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Using xml.etree
On 19/09/2011 11:01, Tim Golden wrote: you're more likely to find people familiar with the package (including its maintainer in fact...) Sorry, I misread your post and thought you were referring lxml.etree (which is a 3rd-party lib). My basic point still stands, though: you'll get more library-specific help on python-list. TJG ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Using xml.etree
Thanks Tim, Will do. Chris On Mon, Sep 19, 2011 at 11:05 AM, Tim Golden m...@timgolden.me.uk wrote: On 19/09/2011 11:01, Tim Golden wrote: you're more likely to find people familiar with the package (including its maintainer in fact...) Sorry, I misread your post and thought you were referring lxml.etree (which is a 3rd-party lib). My basic point still stands, though: you'll get more library-specific help on python-list. TJG ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] How it is better than java
My obvious thinking is : Java being compiled language , must be faster then a interpreted language. I know couple of points : Development time is less + easy to learn + python is expressive. Can you share some more especially as compared to Java / .net (two primarily used languages in enterprise language web based applications) -- Thanks Regards Ashish Gaonker ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] How it is better than java
On 2011/09/19 03:27 PM, Ashish Gaonker wrote: My obvious thinking is : Java being compiled language , must be faster then a interpreted language. I know couple of points : Development time is less + easy to learn + python is expressive. Can you share some more especially as compared to Java / .net (two primarily used languages in enterprise language web based applications) -- Thanks Regards Ashish Gaonker ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor I would suggest reading `Python is not Java` [1] and `Java is not Python, either` [2], old but good reads. And then ask what is your focus for development. Better is extremely subjective and can be liable to induce flame-wars, although this list is quite friendly. To me, I started using Python as a glue language, controlling process flows and the like, with still heavy uses of C and PL/SQL for what I do. Over time Python has taken center-stage for my projects due to ease-of-use and rapid application development and only moving time critical work that needs to be faster to C but in most cases that is not needed for me anymore. Add to that the great work on PyPy [3] which is extremely efficient, I hardly ever have to write in another language if I don't wish. [1] http://dirtsimple.org/2004/12/python-is-not-java.html [2] http://dirtsimple.org/2004/12/java-is-not-python-either.html [3] http://pypy.org/ -- Christian Witts Python Developer // ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] How it is better than java
Hi Ashish, On 19 September 2011 14:27, Ashish Gaonker ashish@gmail.com wrote: My obvious thinking is : Java being compiled language , must be faster then a interpreted language. I know couple of points : Development time is less + easy to learn + python is expressive. Can you share some more especially as compared to Java / .net (two primarily used languages in enterprise language web based applications) There's many pages on the internet comparing Python, Java and other languages. I suggest you check them out. Having said that, I'll point out that Python has several implementations, including one called Jython, which actually targets the Java runtime and so should have comparable performance to Java on the same runtime. Additionally there's projects like PyPy which in some cases is faster even than C/C++. This page (from my bookmarks) has some interesting points of comparison for consideration: http://pythonconquerstheuniverse.wordpress.com/category/java-and-python/ Walter ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] string formatting
Pythonistas,
This is the resolution of a question I asked over the weekend.
The method I was thinking of was in a program I wrote on my work
computer but couldn't remember.
Now I'm at work and I see. It is not including the tuple at the end of
the string nor using a dictionary. There is another way using locals().
I was trying to remember this method:
You some variables say:
X = sky
Y = blue
Print the %(x)s is %(y)s % locals()
the sky is blue
That works! And in cases where I'm replacing over 20 strings it's much
easier than having to include a tuple at the end. Especially when
there's only two or three variables I'm replacing repeatedly, in which
case a dictionary seems like overkill.
Thanks
Matt
Matthew Pirritano, Ph.D.
Research Analyst IV
Medical Services Initiative (MSI)
Orange County Health Care Agency
(714) 568-5648
-Original Message-
From: tutor-bounces+mpirritano=ochca@python.org
[mailto:tutor-bounces+mpirritano=ochca@python.org] On Behalf Of
Steven D'Aprano
Sent: Saturday, September 17, 2011 6:58 PM
To: tutor@python.org
Subject: Re: [Tutor] string formatting
Matthew Pirritano wrote:
But I have very large blocks of text and I thought there was another
way
like
X = sky
Y = blue
the %(X)s is %(Y)s
Unless you use the string formatting operator %, strings containing %
are just strings. Large or small, the way you do string formatting is
with the % operator. Python will never do string formatting without an
explicit command to do so:
text % value # Single non-tuple argument
text % (value, value, ...) # Multiple arguments
They don't have to be string literals, they can be variables:
text = Hello, I'd like to have an %s
value = argument
print text % value
You can also use named arguments by using a dictionary:
text = Hello, I'd like to have an %(X)s
values = {X: argument}
print text % values
More details in the Fine Manual:
http://docs.python.org/library/stdtypes.html#string-formatting
Alternatives include the new advanced formatting method:
text.format()
http://docs.python.org/library/string.html#formatstrings
and $ substitutions with the string module:
import string
string.Template
http://docs.python.org/library/string.html#template-strings
--
Steven
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Re: [Tutor] string formatting
On Mon, Sep 19, 2011 at 10:46 AM, Pirritano, Matthew
mpirrit...@ochca.comwrote:
snip
You some variables say:
X = sky
Y = blue
Print the %(x)s is %(y)s % locals()
the sky is blue
That works! And in cases where I'm replacing over 20 strings it's much
easier than having to include a tuple at the end. Especially when
there's only two or three variables I'm replacing repeatedly, in which
case a dictionary seems like overkill.
I suspect your email program auto-capitalized the initial X and Y, and P for
you, as that code would actually create a syntax and KeyError (or two).
Technically speaking, locals() is already dictionary:
type(locals())
class 'dict'
and just for the sake of completeness, in newer (2.6(?) or greater) versions
of Python, you can use the format() method:
x = 'sky'
y = 'blue'
print('The {x} is {y}.'.format(locals()))
HTH,
-Wayne
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Re: [Tutor] string formatting
Is there any additional overhead of using the locals() or format(locals()) instead of a tuple? - the format option is a double function call so I would expect that to be considerably slower Thanks, Bodsda -- my phone won't let me bottom post, sorry Sent from my BlackBerry® wireless device -Original Message- From: Wayne Werner waynejwer...@gmail.com Sender: tutor-bounces+bodsda=googlemail@python.org Date: Mon, 19 Sep 2011 12:47:01 To: Pirritano, Matthewmpirrit...@ochca.com Cc: tutor@python.org Subject: Re: [Tutor] string formatting ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] string formatting
On Mon, Sep 19, 2011 at 1:11 PM, bod...@googlemail.com wrote:
Is there any additional overhead of using the locals() or format(locals())
instead of a tuple? - the format option is a double function call so I would
expect that to be considerably slower
Using the following code and timeit, it appears that there is a difference,
but unless you call 0.3-6 ns considerable (assuming I got my math correct:
The difference was ~1.2 or ~1.3 seconds for the classic, ~1.9 for the %
locals version, and timeit runs 1,000,000 times with the default settings),
then the difference isn't terrible.
-Wayne
from __future__ import print_function
import timeit
def classicwithlocals():
x = 'hello'
from __future__ import print_function
import timeit
def classicwithlocals():
x = 'hello'
y = 'goodbye'
combined = 'You say %(x)s, and I say %(y)s' % locals()
def classicwithtuple():
x = 'hello'
y = 'goodbye'
combined = 'You say %s, and I say %s' % (x, y)
def withargs():
x = 'hello'
y = 'goodbye'
combined = 'You say {0}, and I say {1}'.format(x, y)
for f in [withargs, classicwithtuple, classicwithlocals]:
t = timeit.Timer(f)
print(t.timeit())
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[Tutor] OptionParser
Hello, I am trying to use OptionParser (my first time) to set a variable (cvs_output). i.e. if --csv is given in the list of options, then cvs_output = True. Then I check, if cvs_output == True: [...] I have the following so far but something is missing. from optparse import OptionParser usage = usage: %prog [options] parser = OptionParser(usage=usage) parser.add_option(-cvs, dest=output, default=True, help=outputs the csv file for plotting activites) python dUCx_ActivityPlots.py python dUCx_ActivityPlots.2.py -h Usage: dUCx_ActivityPlots.2.py [options] Options: -h, --help show this help message and exit --cvs=OUTPUT_FLAG outputs the csv file for plotting activities I don't really understand what dest and action in the arguments to parser.add_option mean. Any help is appreciated. Mina ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] OptionParser
On Mon, Sep 19, 2011 at 1:22 PM, Mina Nozar noz...@triumf.ca wrote: ** I don't really understand what dest and action in the arguments to parser.add_option mean. Any help is appreciated. Have you read the fine manual, specifically the sections here: http://docs.python.org/library/optparse.html#optparse-standard-option-actions and here: http://docs.python.org/library/optparse.html#option-attributes Additionaly, I'm not sure you copied your code correctly, because after a copy and paste I get this: $ python localtest.py Traceback (most recent call last): File localtest.py, line 5, in module parser.add_option(-cvs, dest=output, default=True, help=outputs the csv file for plotting activites) File /usr/lib/python2.6/optparse.py, line 1012, in add_option option = self.option_class(*args, **kwargs) File /usr/lib/python2.6/optparse.py, line 566, in __init__ self._set_opt_strings(opts) File /usr/lib/python2.6/optparse.py, line 606, in _set_opt_strings self) optparse.OptionError: invalid long option string '-cvs': must start with --, followed by non-dash and when I correct that: $ python localtest.py -h uwwerne@WWERNER /c $ I get no output. HTH, Wayne ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Using xml.etree
On 17/09/11 13:08, lists wrote:
I have been trying to learn how to parse XML with Python and learn how
to use xml.etree. Lots of the tutorials seem to be very long winded.
I'm trying to access a UK postcode API at www.uk-postcodes.com to take
a UK postcode and return the lat/lng of the postcode. This is what the
XML looks like: http://www.uk-postcodes.com/postcode/HU11AA.xml
The function below returns a dict with the xml tag as a key and the
text as a value. Is this a correct way to use xml.etree?
Define correct, does it give the desired result? Then I would say yes it
is correct. There may be alternative ways to get to the same result though.
def ukpostcodesapi(postcode):
import urllib
Why do the import here, for speed? You are reading an xml file from the
internet, guess where most of the time is spend in your function ;-).
import xml.etree.ElementTree as etree
baseURL='http://www.uk-postcodes.com/'
geocodeRequest='postcode/'+postcode+'.xml'
You could use string formatting here.
url = 'http://www.uk-postcodes.com/postcode/%s.xml' % postcode
Also what would happen if postcode includes a space?
#grab the xml
tree=etree.parse(urllib.urlopen(baseURL+geocodeRequest))
What happens if you get an error (a 404 error perhaps)? You might want
to add a try/except block around reading the xml from the internet.
root=tree.getroot()
results={}
for child in root[1]: #here's the geo tag
results.update({child.tag:child.text}) #build a dict containing
the
geocode data
return results
As you only get 1 set of long/lat tags in the xml you could use find().
See below an example.
from xml.etree import ElementTree as ET
import urllib2
url = 'http://www.uk-postcodes.com/postcode/HU11AA.xml'
xml = urllib2.urlopen(url).read()
tree = ET.XML(xml)
geo = {}
for leaf in tree.find('geo'):
geo[leaf.tag] = leaf.text
Greets
Sander
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Re: [Tutor] Using xml.etree
On Mon, Sep 19, 2011 at 9:20 PM, Sander Sweers sander.swe...@gmail.com wrote:
On 17/09/11 13:08, lists wrote:
I have been trying to learn how to parse XML with Python and learn how
to use xml.etree. Lots of the tutorials seem to be very long winded.
I'm trying to access a UK postcode API at www.uk-postcodes.com to take
a UK postcode and return the lat/lng of the postcode. This is what the
XML looks like: http://www.uk-postcodes.com/postcode/HU11AA.xml
The function below returns a dict with the xml tag as a key and the
text as a value. Is this a correct way to use xml.etree?
Define correct, does it give the desired result? Then I would say yes it is
correct. There may be alternative ways to get to the same result though.
def ukpostcodesapi(postcode):
import urllib
Why do the import here, for speed? You are reading an xml file from the
internet, guess where most of the time is spend in your function ;-).
import xml.etree.ElementTree as etree
baseURL='http://www.uk-postcodes.com/'
geocodeRequest='postcode/'+postcode+'.xml'
You could use string formatting here.
url = 'http://www.uk-postcodes.com/postcode/%s.xml' % postcode
Also what would happen if postcode includes a space?
#grab the xml
tree=etree.parse(urllib.urlopen(baseURL+geocodeRequest))
What happens if you get an error (a 404 error perhaps)? You might want to
add a try/except block around reading the xml from the internet.
root=tree.getroot()
results={}
for child in root[1]: #here's the geo tag
results.update({child.tag:child.text}) #build a dict
containing the
geocode data
return results
As you only get 1 set of long/lat tags in the xml you could use find(). See
below an example.
from xml.etree import ElementTree as ET
import urllib2
url = 'http://www.uk-postcodes.com/postcode/HU11AA.xml'
xml = urllib2.urlopen(url).read()
tree = ET.XML(xml)
geo = {}
for leaf in tree.find('geo'):
geo[leaf.tag] = leaf.text
Greets
Sander
Thank you
I've been working on this and ended up with http://pastebin.com/Y9keC9tB
Chris
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[Tutor] iretator.send
Dear tutor dudes, I know that a for loop uses a an iterators next method in this way for variable in iterator: execute_code(variable) is equivalent to while True: try: variable = iterator.next() except StopIteration: break else: execute_code(variable) Is there any syntax that uses the send method of an iterator? ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] iretator.send
Christopher King wrote: Is there any syntax that uses the send method of an iterator? No. -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] How it is better than java
Ashish Gaonker wrote: My obvious thinking is : Java being compiled language , must be faster then a interpreted language. There are three misunderstandings with that statement. Firstly: Languages are neither compiled or interpreted. Languages are syntax and grammar. Implementations are either compiled, or interpreted, or both: for example, there are C interpreters and C compilers. And the quality of both can vary significantly. Asking which language is faster is like asking which is faster, Ford or Toyota? That depends on the particular model, and the conditions, and the skill of the driver. It is ironic that you contrast Java as compiled and Python as interpreted, because that is *marketing*. When Java first came out, Sun didn't want people describing it as interpreted, which it was, so they popularized the term byte-code compiler just so that they could talk about Java being compiled. Java would compile your Java source code to byte-code which was then interpreted by a virtual machine. That is *exactly* what Python does: it compiles Python source code to byte-code which is interpreted by a virtual machine, just like Java. What do you think the .pyc files contain, and what the compile() function does? And yet, even back in the 1980s, everybody swallowed Sun's marketing and called Java a compiled language and Python an interpreted language. This is a testament to Sun spending millions in advertising. Byte-code compilation is a lot older than Java. Pascal used something similar in the early 1970s, called a p-machine. Even Apple's Hypertalk did the same thing, only they called it tokenized code instead of compiled. Java's big innovation was to convince people to use the term compiler for what was functionally identical to an interpreter. Of course, Sun (now owned by Oracle) put in a lot of money into Java. Millions. Today, Java does have implementations which compile source code to machine code. But there are Python implementations that do the same, such as Nuitka and Compyler. (I don't know how successful or good they are.) Secondly, what do you mean by faster? Faster to write? Faster to compile? Faster to run? Faster for the engine to start up? Even today, after Sun has spent tens of millions on Java development, the Java Runtime Environment is a big, heavyweight machine that takes a long time to start up: cold starts can easily take 30 seconds. That makes Java completely unsuitable for small, lightweight tasks: in the time it takes for a *single* Java program just to start up, you could possibly run a dozen Python programs or a hundred interpreted bash scripts. But again, that's an *implementation*, not a hard rule about Java. There is at least one third-party JRE which claims to have startup times twice as fast as the Sun/Oracle JRE. Either way, once you take startup time into account, sometimes Python scripts are not only faster to write and faster to maintain, but faster to run as well. Thirdly, there is no rule of nature that a compiled program to do a job must be faster than an interpreted program to do the same thing. This depends entirely on the quality of implementation of both: a poor compiler may easily generate bad, slow code that takes longer to run than a wickedly fast and efficient interpreter. E.g. a compiled version of bubblesort will still be slower than an interpreted version of quicksort. Nothing drives this home more than PyPy, a Just In Time optimizing version of Python. PyPy uses a JIT compiler to run code sometimes FASTER than the equivalent program in optimized C. Yes. Faster than C. You read that right. http://morepypy.blogspot.com/2008/01/rpython-can-be-faster-than-c.html http://morepypy.blogspot.com/2011/02/pypy-faster-than-c-on-carefully-crafted.html http://morepypy.blogspot.com/2011/08/pypy-is-faster-than-c-again-string.html Of course, benchmarks are notoriously flawed, especially micro- benchmarks. What they *really* answer is not which language is faster? (a nonsense question, as I have tried to explain) but which implementation is faster with these particular settings on this particular task?, a much more practical question. As exciting as it is to see Python code run faster than C code, it shouldn't really surprise anyone that a JIT dynamic compiler with cross module optimization beats a static compiler without it. What *is* surprising is that a small group of open-source developers have been able to build an optimizing JIT compiler for Python of such quality. Or at least, it is surprising to people who think that quality code can only come from big proprietary companies with huge budgets. What's really exciting though is that now PyPy can be fast enough for large programs that traditionally needed to be written in C can now be (sometimes!) written in Python: http://morepypy.blogspot.com/2011/07/realtime-image-processing-in-python.html Who cares whether Java, or C, is faster
Re: [Tutor] string formatting
Wayne Werner wrote: On Mon, Sep 19, 2011 at 1:11 PM, bod...@googlemail.com wrote: Is there any additional overhead of using the locals() or format(locals()) instead of a tuple? - the format option is a double function call so I would expect that to be considerably slower Using the following code and timeit, it appears that there is a difference, but unless you call 0.3-6 ns considerable (assuming I got my math correct: The difference was ~1.2 or ~1.3 seconds for the classic, ~1.9 for the % locals version, and timeit runs 1,000,000 times with the default settings), then the difference isn't terrible. I get similar speeds with Python 2.7: for f in [withargs, classicwithtuple, classicwithlocals]: ... t = timeit.Timer(f) ... print(t.timeit()) ... 1.72170519829 1.18233394623 1.96000385284 However, a single reading with timeit is subject to a lot of noise. Trying again: for f in [withargs, classicwithtuple, classicwithlocals]: ... t = timeit.Timer(f) ... print(min(t.repeat(repeat=5))) # Best of five runs. ... 1.19279980659 1.01878404617 1.56821203232 So, roughly speaking, it looks like the format method is about 20% slower than % with a tuple, and using locals is about 60% slower. -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
