date:20090923


On 05:55 am, jacopo.pe...@gmail.com wrote:

I am diving into Twisted and Perspective Broker (PB) in particular. I
am designing a system  having several models running on different
machines, they need to be recalculated periodically, I have to collect
the results, process them and start again from the beginning.

It is not clear to me if I can blend some event driven programming
with a more traditional one where the flow would be deterministic.
In my case I have to iterate on a list of models and send the request
of recalculation to the specific machine where the model resides. I
don 19t want to wait for each single result but I want to sent all the
requests in one go. In this phase I am happy to have an event driven
framework with callbacks. Then I have to stop and wait for all the
results to be ready, I collect and process them. From now on I don 19t
need a the system to be event drive any more, the processing should
occur only on the master machine, following a deterministic flow.
As soon as finished I am ready to start again to resubmit the models
for recalculation and so on. This should go on forever.

Is  it possible to have an hybrid system like this? If I call
reactor.spot() at the certain point of the execution where does the
execution continue from? Would this be a good design or in general is
better to keep a 100% event drive system even if I don 19t actually need
to handle asynchronicity for big chunks of the code.


If you're happy to block event processing, then there's no reason you 
can't do just that - once you have your results, start processing them 
in a blocking manner.  Twisted will not service events while you're 
doing this, but as long as you're happy with that, it doesn't really 
matter to Twisted.  You might not be as happy with this later on if your 
requirements change, but you can always worry about that later.


In particular, though, there's no reason or need to call reactor.stop() 
in order to switch to your non-event driven code.  Wherever you were 
thinking of putting that call, just put your non-event driven code there 
instead.


Jean-Paul
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Re: Solved - Python: automate input to MySQL query

2009-09-23 Thread D'Arcy J.M. Cain

On Tue, 22 Sep 2009 22:36:15 -0700
Dennis Lee Bieber wlfr...@ix.netcom.com wrote:
   I wasn't really referring to the table used as a qualifier (in front
 of the .). But in your sample statement, every /field/ name seemed to
 contain the table name too...
 
   traveler.travelerFirstName
 
 rather than being just
 
   traveler.FirstName

I do that all the time.  Many of my tables have an ID, an active flag
and other fields such as first name like this example.  Putting the
table name into the field name simplifies joins.  Consider the
following (untested) code.

from pg import DB # PyGreSQL
db = DB() # uses my default PostgeSQL database
res = db.query(
SELECT * FROM employee, manager
WHERE manager.id = employee.id).dictresult()
print res[0]['id'] # is this the employee's ID or the manager's?
print res[0]['firstname'] # same question

Of course you can get around this by specifying every field and using
AS to change the names to manager_id and employee_firstname, etc. but
if you are going to do that anyway, why not just do it once in the
database instead of littering the code?

In my databases I make sure that every field name is unique across all
tables unless the field actually refers the the same item (i.e. joining
field) so that I never have an accident.  My manager table would have a
manager_id and the employee table would have an employee_id.  The
employee table would also have a manager_id but it is not a different
field.  It's the same field as in the manager table.

-- 
D'Arcy J.M. Cain da...@druid.net |  Democracy is three wolves
http://www.druid.net/darcy/|  and a sheep voting on
+1 416 425 1212 (DoD#0082)(eNTP)   |  what's for dinner.
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Re: Twisted: 1 thread in the reactor pattern


On 06:08 am, jacopo.pe...@gmail.com wrote:

I am diving into Twisted and Perspective Broker (PB) in particular and
I would like to understand more about what happens behind the
curtains.
Say I have a client and a server on two different machines, the server
gets callRemote() 19s in an asynchronous way, these requests are parked
in a queue and then served sequentially (not in parallel  13 correct me
if I am wrong).


Since, as you point out below, there is only one thread, the remote 
methods can only be invoked one at a time.


However, rather central to the asynchronous operation of Twisted 
libraries and applications, the remote method itself may return before 
the remote call has been completely serviced.  So while only one remote 
method will run at a time, each of the two remote calls may run 
concurrently at some point before they are responded to.

If everything is implemented in a single thread, how
is it possible that while the processor is engaged in the processing
triggered by  callRemote() 19s at the same time the reactor is ready to
listen/accept new events and put them in a queue? To me it looks like
there should be at least 2 processes, one for the reactor and on for
the rest.


It isn't possible.  While the remote methods are running, other events 
are not being serviced.  This is what is meant when people describe 
Twisted as a *cooperative* multitasking system.  Event handlers (such 
as remote methods) run for a short enough period of time that it doesn't 
matter that the reactor is prevented from accepting new connections (or 
what have you) for the duration of their execution.


Jean-Paul
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Copy directory tree without copying files

I am trying to copy a folder hierarchy from one location to another.
I can use the shutil.copytree function to copy the folder tree, but I
don't want the files copied, just the folders.  What is a good way to
approach this?

Thanks,
Jeremy
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Re: Copy directory tree without copying files

2009-09-23 Thread Tim Golden


Jeremy Conlin wrote:

I am trying to copy a folder hierarchy from one location to another.
I can use the shutil.copytree function to copy the folder tree, but I
don't want the files copied, just the folders.  What is a good way to
approach this?

Thanks,
Jeremy


Use os.walk and create the directories as they appear?

TJG
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Re: Copy directory tree without copying files

2009-09-23 Thread dwatrous

Have you considered using os.walk?
http://docs.python.org/library/os.html#os.walk

It won't be completely automated, but I think it should allow you to
easily walk the directory structure to reproduce it in another
location.

If the file names/extensions are predictable you might also be able to
use the ignore attribute in the shutil.copytree function to prevent
copying files:
http://docs.python.org/library/shutil.html#shutil.copytree

Daniel

On Sep 23, 9:04 am, Jeremy Conlin jlcon...@gmail.com wrote:
 I am trying to copy a folder hierarchy from one location to another.
 I can use the shutil.copytree function to copy the folder tree, but I
 don't want the files copied, just the folders.  What is a good way to
 approach this?

 Thanks,
 Jeremy

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Re: Copy directory tree without copying files

On Sep 23, 9:15 am, Tim Golden m...@timgolden.me.uk wrote:
 Jeremy Conlin wrote:
  I am trying to copy a folder hierarchy from one location to another.
  I can use the shutil.copytree function to copy the folder tree, but I
  don't want the files copied, just the folders.  What is a good way to
  approach this?

  Thanks,
  Jeremy

 Use os.walk and create the directories as they appear?

 TJG

I was hoping to use os.walk, but this doesn't work because I wont know
when os.walk descends into a new directory or which directory it
descends into.  Perhaps I don't understand everything about it.

Thanks,
Jeremy
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Re: Copy directory tree without copying files

2009-09-23 Thread Tim Golden


Jeremy Conlin wrote:

On Sep 23, 9:15 am, Tim Golden m...@timgolden.me.uk wrote:

Jeremy Conlin wrote:

I am trying to copy a folder hierarchy from one location to another.
I can use the shutil.copytree function to copy the folder tree, but I
don't want the files copied, just the folders.  What is a good way to
approach this?
Thanks,
Jeremy

Use os.walk and create the directories as they appear?

TJG


I was hoping to use os.walk, but this doesn't work because I wont know
when os.walk descends into a new directory or which directory it
descends into.  Perhaps I don't understand everything about it.


Some rough but working code might help you out here:

code
import os

source_dir = c:/temp/oldtree
target_dir = c:/temp/newtree # should not exist yet

for dirpath, dirnames, filenames in os.walk (source_dir):
 os.mkdir (os.path.join (target_dir, dirpath[1+len (source_dir):]))

os.startfile (target_dir)

/code

TJG
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Re: Copy directory tree without copying files

2009-09-23 Thread Peter Otten

Jeremy Conlin wrote:

 I am trying to copy a folder hierarchy from one location to another.
 I can use the shutil.copytree function to copy the folder tree, but I
 don't want the files copied, just the folders.  What is a good way to
 approach this?

The easiest is

def ignore(folder, names):
return set(n for n in names if not
   os.path.isdir(os.path.join(folder, n)))

shutil.copytree(source, dest, ignore=ignore)

Peter

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Re: Copy directory tree without copying files

On Sep 23, 9:15 am, dwatrous daniel.watr...@gmail.com wrote:
 Have you considered using 
 os.walk?http://docs.python.org/library/os.html#os.walk

 It won't be completely automated, but I think it should allow you to
 easily walk the directory structure to reproduce it in another
 location.

 If the file names/extensions are predictable you might also be able to
 use the ignore attribute in the shutil.copytree function to prevent
 copying files:http://docs.python.org/library/shutil.html#shutil.copytree

 Daniel


Thanks, that helps.  I could write a function like

def ignore_files(dirpath):
ignore = []
for f in os.listdir(dirpath)
if os.path.isfile(f):
ignore.append(f)
return ignore


That seems like it will work (haven't tested yet).  Thanks for the
help.
Jeremy


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cleanup in sys.excepthook?

hello,

my script creates files that i need to delete if an exception is
thrown.

is this a good pythonic style to do this kind of cleanup in
sys.excepthook instead of inside except clause of a try block?

konstantin
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Re: Copy directory tree without copying files

On Sep 23, 9:31 am, Tim Golden m...@timgolden.me.uk wrote:
 Jeremy Conlin wrote:
  On Sep 23, 9:15 am, Tim Golden m...@timgolden.me.uk wrote:
  Jeremy Conlin wrote:
  I am trying to copy a folder hierarchy from one location to another.
  I can use the shutil.copytree function to copy the folder tree, but I
  don't want the files copied, just the folders.  What is a good way to
  approach this?
  Thanks,
  Jeremy
  Use os.walk and create the directories as they appear?

  TJG

  I was hoping to use os.walk, but this doesn't work because I wont know
  when os.walk descends into a new directory or which directory it
  descends into.  Perhaps I don't understand everything about it.

 Some rough but working code might help you out here:

 code
 import os

 source_dir = c:/temp/oldtree
 target_dir = c:/temp/newtree # should not exist yet

 for dirpath, dirnames, filenames in os.walk (source_dir):
   os.mkdir (os.path.join (target_dir, dirpath[1+len (source_dir):]))

 os.startfile (target_dir)

 /code

 TJG

Perfect.  That's exactly what I needed.
Jeremy
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Re: Copy directory tree without copying files

2009-09-23 Thread Grant Edwards

On 2009-09-23, Jeremy Conlin jlcon...@gmail.com wrote:

 I am trying to copy a folder hierarchy from one location to another.
 I can use the shutil.copytree function to copy the folder tree, but I
 don't want the files copied, just the folders.  What is a good way to
 approach this?

Just in case there's no real requirement to use Python...

$ (cd srcdir; find . -type d) | (cd dstdir; xargs mkdir)

-- 
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  at   on a wild rampage through a
   visi.comLong Island Bowling Alley!!
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Re: custom data warehouse in python vs. out-of-the-box ETL tool

2009-09-23 Thread nn

On Sep 22, 4:00 pm, snfctech tschm...@sacfoodcoop.com wrote:
 Does anyone have experience building a data warehouse in python?  Any
 thoughts on custom vs using an out-of-the-box product like Talend or
 Informatica?

 I have an integrated system Dashboard project that I was going to
 build using cross-vendor joins on existing DBs, but I keep hearing
 that a data warehouse is the way to go.  e.g. I want to create orders
 and order_items with relations to members (MS Access DB), products
 (flat file) and employees (MySQL).

 Thanks in advance for any tips.

I use both Python and a Data-warehouse tool (Datastage) from IBM that
is similar to Informatica. The main difference with Python is
throughput. The tool has good sort and join routines of multithreaded
C code that handles data bigger than what fits in RAM. It also has
good native drivers for the DB2 database. For data conversions and
other transformations every row gets processed on a different CPU. You
can really put a 16 core machine to good use with this thing.

In your case you probably won't have enough data to justify the cost
of buying a tool. They are quite expensive.
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Re: Very simple finite automaton (?)

On Sep 23, 1:24 am, kpp9c k...@mac.com wrote:
 Very simple finite automaton (?)

 1 -- 2 5
 2 -- 1 4
 3 -- 3
 4 -- 1
 5 -- 4 3


hello,
this is a graph and you are doing depth first search.
konstantin
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Re: cleanup in sys.excepthook?

2009-09-23 Thread MRAB


akonsu wrote:

hello,

my script creates files that i need to delete if an exception is
thrown.

is this a good pythonic style to do this kind of cleanup in
sys.excepthook instead of inside except clause of a try block?


Speaking personally, I'd do the cleanup in the except clause if they
needed to be deleted only if there was an exception; I'd use a finally
clause or a 'with' context if they always had to be deleted, whether
there was an exception or not.
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Re: Very simple finite automaton (?)

On Sep 23, 11:49 am, akonsu ako...@gmail.com wrote:
 On Sep 23, 1:24 am, kpp9c k...@mac.com wrote:

  Very simple finite automaton (?)

  1 -- 2 5
  2 -- 1 4
  3 -- 3
  4 -- 1
  5 -- 4 3

 hello,
 this is a graph and you are doing depth first search.
 konstantin

BREADTH first. sorry :)
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Re: cleanup in sys.excepthook?

2009-09-23 Thread Jean-Michel Pichavant


akonsu wrote:

hello,

my script creates files that i need to delete if an exception is
thrown.

is this a good pythonic style to do this kind of cleanup in
sys.excepthook instead of inside except clause of a try block?

konstantin
  

def doIt():
   pass

try:
   doIt()
except Exception, exc:
   #cleaning up files



I mean, what is the problem with try except ? It's pythonic. If you tell 
us what wrong with it in your case, we may spend time on hacking 
sys.excepthook.


Jean-Michel
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Re: Very simple finite automaton (?)

2009-09-23 Thread duncan smith

kpp9c wrote:
 Very simple finite automaton (?)
 
 I am not sure if this is and example of Finite Automaton or a Finite
 State Machine or perhaps it is related to a transition table or markov
 process. I am not a math person so i am not sure what it is called. I
 googled around and got lots of super complicated gobbledegoo all with
 knotty regex stuff, but what i want to do is much more simple.
 
 I am trying to use a table (called a transition table? i dunno) to
 define a bunch of moves like so:
 
 1 -- 2 5
 2 -- 1 4
 3 -- 3
 4 -- 1
 5 -- 4 3
 
 so that i can generate a sequence that, given an initial value, will
 continue to grow according to these rules.
 
 So starting with 1, we get:
 
 1
 2 5
 1 4 4 3
 2 5 1 1 3
 1 4 4 3 2 5 2 5 3
 
 
 . etc.
 
 Essentially, iterating over the last added items to the list, applying
 the table, adding those new items to the list, applying the table
 again... etc, until the sequence reaches some predetermined number of
 iterations and quits.
 
 
 [ [1], [2, 5], [1, 4] , [4, 3], [2, 5], [1], [1], [3], [1, 4], [4, 3],
 [2, 5], [2, 5], [3] ]
 

[snip]

I'm interested to know what you're then doing with the list.  Depending
on that you might want to view it (or implement it) in terms of a
matrix, graph ...

Duncan
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Re: Most active coroutine library project?

2009-09-23 Thread Brian Hammond

On Aug 25, 12:51 am, Denis denis.bile...@gmail.com wrote:
 You can also at gevent

 http://pypi.python.org/pypi/gevent

Please, please document this!  There are a lot of people who would
love to use this but give up when they don't find a guide or something
similar.
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Re: cleanup in sys.excepthook?

On Sep 23, 11:57 am, Jean-Michel Pichavant jeanmic...@sequans.com
wrote:
 akonsu wrote:
  hello,

  my script creates files that i need to delete if an exception is
  thrown.

  is this a good pythonic style to do this kind of cleanup in
  sys.excepthook instead of inside except clause of a try block?

  konstantin

 def doIt():
     pass

 try:
     doIt()
 except Exception, exc:
     #cleaning up files

 I mean, what is the problem with try except ? It's pythonic. If you tell
 us what wrong with it in your case, we may spend time on hacking
 sys.excepthook.

 Jean-Michel

thanks. nothing is wrong with try/except. i just already have an
excepthook handler that uses logger to send emails if a critical error
occurs, so i was just thinking that maybe i can add cleanup there. i
agree, try/except makes more sense.

konstantin
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Re: Copy directory tree without copying files

On Sep 23, 9:44 am, Grant Edwards inva...@invalid.invalid wrote:
 On 2009-09-23, Jeremy Conlin jlcon...@gmail.com wrote:

  I am trying to copy a folder hierarchy from one location to another.
  I can use the shutil.copytree function to copy the folder tree, but I
  don't want the files copied, just the folders.  What is a good way to
  approach this?

 Just in case there's no real requirement to use Python...

 $ (cd srcdir; find . -type d) | (cd dstdir; xargs mkdir)

Thanks, but this has to be platform independent so Python seemed like
a good choice.

Jeremy
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Unable to import package over NFS in solaris

2009-09-23 Thread Ashok

Hi,

I have sqlalchemy package installed on the server. However I want to
run a script on the client that uses the sqlalchemy package. Hence I
shared the directory containing the sqlalchemy unsing NFS. Then I
added the NFS pathname to the sqlalchemy packege in the client
program. Now when I import sqlalchemy in the client program it throws
the following error.

Traceback (most recent call last):
  File /net/sqlhost/ashok/send.py, line 9, in ?
from sqlalchemy import *
ImportError: No module named sqlalchemy


I have added the NFS path to the PYTHONPATH as folllows in my program.

#!/usr/bin/python

import os,commands,sys

os.environ['PYTHONPATH']='/net/sqlhost/usr/lib/python2.4/site-packages/
SQLAlchemy-0.5.6-py2.4.egg/sqlalchemy'
sys.path.append('/net/sqlhost/usr/lib/python2.4/site-packages/
SQLAlchemy-0.5.6-py2.4.egg/sqlalchemy')
from sqlalchemy import *

Contents of the directory shared under NFS in Solaris.

bash-3.00# ls /usr/lib/python2.4/site-packages/SQLAlchemy-0.5.6-
py2.4.egg/sqlalchemy/
__init__.py  engine   ext  log.py
pool.py  queue.pycsql  topological.pyc
util.py
__init__.pyc exc.py   interfaces.pylog.pyc
pool.pyc schema.pytest types.py
util.pyc
databasesexc.pyc  interfaces.pyc   orm
queue.py schema.pyc   topological.py   types.pyc

Please let me know what went wrong?

thx,
~Ashok.
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Re: custom data warehouse in python vs. out-of-the-box ETL tool

2009-09-23 Thread snfctech

@Martin:  I originally thought that there was nothing magical about
building a data warehouse, but then I did a little research and
received all sorts of feedback about how data warehouse projects have
notorious failure rates, that data warehouse design IS different than
normal RDBMS - and then there's the whole thing about data marts vs.
warehouses, Kimball vs. Inmon, star schemas, EAV tables, and so on.
So I started to think that maybe I needed to get a little better read
on the subject.

On Sep 23, 3:15 am, Martin P. Hellwig martin.hell...@dcuktec.org
wrote:
 snfctech wrote:
  Thanks for your replies, Sean and Martin.

  I agree that the ETL tools are complex in themselves, and I may as
  well spend that learning curve on a lower-level tool-set that has the
  added value of greater flexibility.

  Can you suggest a good book or tutorial to help me build a data
  warehouse in python?  Bill Inmon's Building the Data Warehouse is 17
  years old, and I've been cautioned against Kimball.

  Thanks.

 cut

 Data warehouse isn't something magical, it is just another database,
 albeit containing multiple datasets gathered from foreign resources in
 possibly multiple formats.

 Depending on your purpose of what you want, you design your tables the
 way you usually do. For example if you only want reporting, you might
 want to build your tables in such a way so it makes your life easier to
 build the actual report.

 Now you have an empty database containing the fields you wish for the
 report and have filled database(s) containing data from the user
 application. Now you use Python to fill the empty database, tada, you
 have a Data warehouse and used Python for ETL processing.

 So if you already have some insights in creating tables in a database,
 you are all set. Most likely you will go through a number of iterations
 before you are happy with the result though.

 There is no book substitute for applying theory, experience and common
 sense to a problem you want to solve, unless you write it yourself for
 that specific situation.

 --
 MPHhttp://blog.dcuktec.com
 'If consumed, best digested with added seasoning to own preference.'

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Re: custom data warehouse in python vs. out-of-the-box ETL tool

2009-09-23 Thread snfctech

@Lemburg: Thanks for the suggestion.  I'm sure you make a fine
product, but my development platform is Linux, and I don't want any
additional Windows servers to deal with (than the ones I'm already
stuck with.)

On Sep 23, 2:02 am, M.-A. Lemburg m...@egenix.com wrote:
 snfctech wrote:
  Does anyone have experience building a data warehouse in python?  Any
  thoughts on custom vs using an out-of-the-box product like Talend or
  Informatica?

  I have an integrated system Dashboard project that I was going to
  build using cross-vendor joins on existing DBs, but I keep hearing
  that a data warehouse is the way to go.  e.g. I want to create orders
  and order_items with relations to members (MS Access DB), products
  (flat file) and employees (MySQL).

  Thanks in advance for any tips.

 You might want to look at this solution for doing cross-database JOINs:

 EasySoft ODBC Join-Engine:

    http://www.easysoft.com/products/data_access/odbc_odbc_join_engine/in...

 and then use our mxODBC to access EasySoft's Engine:

    http://www.egenix.com/products/python/mxODBC/

 or mxODBC Connect, if you have a client-server setup:

    http://www.egenix.com/products/python/mxODBCConnect/

 Some database engines also allow integrating external ODBC
 data sources - the external tables then look like normal
 database tables and can be used in JOINs as well. I know that DB2
 and Oracle support this kind of setup. You can access those using
 mxODBC as well.

 --
 Marc-Andre Lemburg
 eGenix.com

 Professional Python Services directly from the Source  (#1, Sep 23 2009) 
 Python/Zope Consulting and Support ...        http://www.egenix.com/
  mxODBC.Zope.Database.Adapter ...            http://zope.egenix.com/
  mxODBC, mxDateTime, mxTextTools ...        http://python.egenix.com/

 

 ::: Try our new mxODBC.Connect Python Database Interface for free ! 

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     D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg
            Registered at Amtsgericht Duesseldorf: HRB 46611
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Re: Dynamic Form

2009-09-23 Thread Victor Subervi

I've been trying the hidden field, but the problem is that when I set the
variable flag, it stays in memory. I would rather just pass a var like I've
been trying, but I don't think it's possible. Any ideas? Is a session cookie
the only way? Here's more simplified code:

#!/usr/bin/python

import cgitb; cgitb.enable()
import cgi
import sys,os
sys.path.append(os.getcwd())
import MySQLdb
import string, re

def client():
  form = cgi.FieldStorage()
  client = string.replace(string.replace(form.getfirst('client', ''), ',
'#39;'), '', '#34;')
  flag = form.getfirst('flag', '')
  print Content-Type: text/html
  print
  print 
!DOCTYPE html PUBLIC -//W3C//DTD XHTML 1.0 Frameset//EN 
http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd;
head xmlns=http://www.w3.org/1999/xhtml;
body

  if flag == '':
print 
form method=post action=client.py
Company Name: input type='text' value='' size='20' maxlength='100'
name='client' /br /
input type='hidden' name='flag' value='y' /
div align='center'
  input type='submit' value=' Send ' /
/div
/form
/body/html

  else:
host = 'h'
db = 'db'
user = 'u'
passwd = '1'
database = MySQLdb.connect(host, user, passwd, db)
cursor = database.cursor()
cursor.execute('insert into companies (client);' % (client))
cursor.close()
print '/body/html'

client()

TIA,
V

On Tue, Sep 22, 2009 at 1:43 PM, Dennis Lee Bieber wlfr...@ix.netcom.comwrote:

 On Tue, 22 Sep 2009 12:50:31 -0400, Victor Subervi
 victorsube...@gmail.com declaimed the following in
 gmane.comp.python.general:

  Well it's Web stuff, sure, but it's written in python :) The code
 follows.
  The problem is that I haven't figured out how to tell the program that
 the
  user has entered data and to clear the cache of that data so that it's
 not
  re-entered. How do I do that?

 Remember, HTTP is a stateless protocol. EACH submission is
 considered a totally new transaction with no memory of the previous
 processing.

Possible solutions...

 *   Use a session cookie that identifies what phase in the multistep
 processing you are in...

 *   Use a hidden field in the form that defaults to, say False, when
 you first display the form, but then gets set to True during the first
 response process (and is then sent back out with True so the second
 response takes a different branch).

 --
Wulfraed Dennis Lee Bieber   KD6MOG
wlfr...@ix.netcom.com   HTTP://wlfraed.home.netcom.com/

 --
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Re: Unable to import package over NFS in solaris

2009-09-23 Thread Jeff McNeil

On Sep 23, 12:15 pm, Ashok asho...@gmail.com wrote:
 Hi,

 I have sqlalchemy package installed on the server. However I want to
 run a script on the client that uses the sqlalchemy package. Hence I
 shared the directory containing the sqlalchemy unsing NFS. Then I
 added the NFS pathname to the sqlalchemy packege in the client
 program. Now when I import sqlalchemy in the client program it throws
 the following error.

 Traceback (most recent call last):
   File /net/sqlhost/ashok/send.py, line 9, in ?
     from sqlalchemy import *
 ImportError: No module named sqlalchemy

 I have added the NFS path to the PYTHONPATH as folllows in my program.

 #!/usr/bin/python

 import os,commands,sys

 os.environ['PYTHONPATH']='/net/sqlhost/usr/lib/python2.4/site-packages/
 SQLAlchemy-0.5.6-py2.4.egg/sqlalchemy'
 sys.path.append('/net/sqlhost/usr/lib/python2.4/site-packages/
 SQLAlchemy-0.5.6-py2.4.egg/sqlalchemy')
 from sqlalchemy import *

 Contents of the directory shared under NFS in Solaris.

 bash-3.00# ls /usr/lib/python2.4/site-packages/SQLAlchemy-0.5.6-
 py2.4.egg/sqlalchemy/
 __init__.py      engine           ext              log.py
 pool.py          queue.pyc        sql              topological.pyc
 util.py
 __init__.pyc     exc.py           interfaces.py    log.pyc
 pool.pyc         schema.py        test             types.py
 util.pyc
 databases        exc.pyc          interfaces.pyc   orm
 queue.py         schema.pyc       topological.py   types.pyc

 Please let me know what went wrong?

 thx,
 ~Ashok.

You don't need the additional 'sqlalchemy' after the '/net/sqlhost/usr/
lib/python2.4/site-packages/
SQLAlchemy-0.5.6-py2.4.egg/' path.  Using your configuration, Python
is looking for:

/net/sqlhost/usr/lib/python2.4/site-packages/
SQLAlchemy-0.5.6-py2.4.egg/sqlalchemy/sqlalchemy/

As an example, see below.  Note that this is in a virtual environment
that is not part of sys.path by default (I didn't run bin/activate).

[j...@marvin ~]$ export PYTHONPATH=/home/jeff/Work/hostapi/lib/
python2.6/site-packages/SQLAlchemy-0.5.5-py2.6.egg/sqlalchemy/
[j...@marvin ~]$ python -c 'import sqlalchemy'
Traceback (most recent call last):
  File string, line 1, in module
ImportError: No module named sqlalchemy
[j...@marvin ~]$ export PYTHONPATH=/home/jeff/Work/hostapi/lib/
python2.6/site-packages/SQLAlchemy-0.5.5-py2.6.egg/
[j...@marvin ~]$ python -c 'import sqlalchemy'
[j...@marvin ~]$

--
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Jeff
mcjeff.blogspot.com
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Getting return code for a Python script invoked from a Linux shell script

2009-09-23 Thread volcano

Hi, folks,
I have a Python script that is invoked by a shell script. I uses
sys.exit() with a parameter within python.

The calling script is using this line to get the return code:
exit_code = !$

but it fails to get it. What's wrong here? (I am no Linux guru)

Thanks in advance
Mark
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Re: Getting return code for a Python script invoked from a Linux shell script

2009-09-23 Thread Igor Pozgaj

On Wed, 23 Sep 2009 09:51:29 -0700, volcano wrote:

 The calling script is using this line to get the return code: exit_code
 = !$
 
 but it fails to get it. What's wrong here? (I am no Linux guru)


Exit code is obtained with $?, not with !$

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Re: Most active coroutine library project?

On Sun, Aug 23, 2009 at 11:02 AM, Phillip B Oldham
phillip.old...@gmail.com wrote:
 I've been taking a look at the multitude of coroutine libraries
 available for Python, but from the looks of the projects they all seem
 to be rather quiet. I'd like to pick one up to use on a current
 project but can't deduce which is the most popular/has the largest
 community.

 Libraries I looked at include: cogen, weightless, eventlet and
 circuits (which isn't exactly coroutine-based but it's event-driven
 model was intriguing).

 Firstly, are there any others I've missed? And what would the
 consensus be on the which has the most active community behind it?
 --
 http://mail.python.org/mailman/listinfo/python-list


Coroutines are built into the language.  There's a good talk about
them here: http://www.dabeaz.com/coroutines/

HTH,
~Simon
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Re: Getting return code for a Python script invoked from a Linux shell script

2009-09-23 Thread Donn

On Wednesday 23 September 2009 18:51:29 volcano wrote:
 exit_code = !$
I think it's $? to get the code.
\d
-- 
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Font manager : https://savannah.nongnu.org/projects/fontypython/
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Re: Getting return code for a Python script invoked from a Linux shell script

2009-09-23 Thread Jeff McNeil

On Sep 23, 12:51 pm, volcano mark.gey...@gmail.com wrote:
 Hi, folks,
 I have a Python script that is invoked by a shell script. I uses
 sys.exit() with a parameter within python.

 The calling script is using this line to get the return code:
 exit_code = !$

 but it fails to get it. What's wrong here? (I am no Linux guru)

 Thanks in advance
 Mark

Assuming Bash, you'll want $? instead. The '!$' construct is used to
pull the last argument of the previous command.  Also, if I remember
correctly, the history mechanism is disabled within shell scripts.

--
Thanks,

Jeff
mcjeff.blogspot.com
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arrays in python

2009-09-23 Thread Rudolf

Can someone tell me how to allocate single and multidimensional arrays
in python. I looked online and it says to do the following x =
['1','2','3','4']

However, I want a much larger array like a 100 elements, so I cant
possibly do that. I want to allocate an array and then populate it
using a for loop. Thanks for your help.
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tool per conversione e trasformazione dati

2009-09-23 Thread Francesco Stablum

Salve,

lavoro in una ditta dove effettuiamo intensamente conversioni di
database, trasformazione dei dati e raccolta da sorgenti diverse,
successive query per fare dei fix eccetera... insomma, un lavoro
bello complesso.
Mi domandavo, insieme ai miei colleghi, se esistono dei tool/framework
per effetturare operazioni di questo tipo e, allargando il discorso al
di la di python, se esiste una disciplina teorica da dove possiamo
attingere informazioni per riorganizzare i nostri programmi e script.

ringrazio per l'attenzione,
Francesco Stablum

-- 
The generation of random numbers is too important to be left to chance
- Robert R. Coveyou
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Re: arrays in python

2009-09-23 Thread Donn

On Wednesday 23 September 2009 19:14:20 Rudolf wrote:
 I want to allocate an array and then populate it
 using a for loop. 
You don't need to allocate anything, just use the list or dictionary types.

l=[] #empty list
for x in range(1,500):
 l.append(x)

\d
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Re: arrays in python

2009-09-23 Thread Benjamin Kaplan

On Sep 23, 2009, at 1:16 PM, Rudolf yellowblueyel...@gmail.com wrote:

 Can someone tell me how to allocate single and multidimensional arrays
 in python. I looked online and it says to do the following x =
 ['1','2','3','4']

 However, I want a much larger array like a 100 elements, so I cant
 possibly do that. I want to allocate an array and then populate it
 using a for loop. Thanks for your help.


Python lists have a dynamic size so you don't usually do that.
Instead, we use list comprehensions to stick the for loop inside the
list declaration.

[str(x) for x in xrange(100)]



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Re: tool per conversione e trasformazione dati

2009-09-23 Thread Francesco Stablum

I am sorry, the previous mail was intended to be published to the
italian python mailing list, but... whoops, autocomplete tricked me...
I will translate it in English:

Hello,

I work in a company where we do intensively database conversions, data
transformations from different sources, queries of fixes... a very
complex job.
I was wondering if there are any tool/frameworks to do such operations
and if there exist a theoretical scientific branch where we can get
some more informations to reorganize our scripts and programs.

thanks for the attention,
Francesco Stablum

2009/9/23 Francesco Stablum stab...@gmail.com:
 Salve,

 lavoro in una ditta dove effettuiamo intensamente conversioni di
 database, trasformazione dei dati e raccolta da sorgenti diverse,
 successive query per fare dei fix eccetera... insomma, un lavoro
 bello complesso.
 Mi domandavo, insieme ai miei colleghi, se esistono dei tool/framework
 per effetturare operazioni di questo tipo e, allargando il discorso al
 di la di python, se esiste una disciplina teorica da dove possiamo
 attingere informazioni per riorganizzare i nostri programmi e script.

 ringrazio per l'attenzione,
 Francesco Stablum

 --
 The generation of random numbers is too important to be left to chance
 - Robert R. Coveyou




-- 
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- Robert R. Coveyou
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Re: arrays in python

2009-09-23 Thread Michel Claveau - MVP

Hi!

See:
   http://docs.python.org/tutorial

(section 5)

@+
-- 
MCI

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Re: Twisted 100% event driven or hybrid?

2009-09-23 Thread Mike C. Fletcher

exar...@twistedmatrix.com wrote:
 On 05:55 am, jacopo.pe...@gmail.com wrote:
...
 results to be ready, I collect and process them. From now on I don 19t
 need a the system to be event drive any more, the processing should
 occur only on the master machine, following a deterministic flow.
 As soon as finished I am ready to start again to resubmit the models
 for recalculation and so on. This should go on forever.
Jean-Paul is obviously far more authoritative on the twisted way than
I am, so if he says you can just run your synchronous operation in-situ,
that's probably the way to go, but IIRC there's a
reactor.deferToThread() function which can run your synchronous code
off to the side, while allowing the twisted code to continue to
process incoming operations.  Thus you'd do something like:

def process( dataset ):
dl = [ remote_call( x ) for x in dataset]
dl = defer.DeferredList( dl )
def on_all_results( results ):
reactor.deferToThread( sync_process, (results,)).addCallback(
process )
return dl.addCallback( on_all_results )

(I'm typing all of that from the distance of a few years of memory
decay, so take it as loosely this, with the proper function names and
the like).  Threads aren't really part of the twisted way in my
understanding, but they can be used if necessary AFAIK, and they will
let your application remain responsive to network events during the
processing.

HTH,
Mike

-- 

  Mike C. Fletcher
  Designer, VR Plumber, Coder
  http://www.vrplumber.com
  http://blog.vrplumber.com

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Get error message from FTPLib

2009-09-23 Thread Bakes

I am using ftplib for a project, using a try/except loop.

I would like to find out the exception, but I am a python newbie and
do not know how.

How, in a try/except loop would I find the ftplib exception?
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Re: [SQL] Pick random rows from SELECT?

2009-09-23 Thread Gilles Ganault

On Mon, 21 Sep 2009 21:40:02 -0700, Dennis Lee Bieber
wlfr...@ix.netcom.com wrote:
   I'd suggest either a pool of threads -- 5-10, each reading company
names from a shared QUEUE, which is populated by the main thread
(remember to commit() so that you don't block on database updates by the
threads). OR... determine how many companies there are, and start
threads feeding them start and length (length being #names /
#threads, round up -- start then being 0*length+1, 1*length+1, etc...)
and use those in thread specific selects using ... limit length
offset start... This way each thread retrieves its own limited set of
companies (make sure to use the same sorting criteria).

Thanks for the help :)
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Re: Most active coroutine library project?


On 05:00 pm, sajmik...@gmail.com wrote:

On Sun, Aug 23, 2009 at 11:02 AM, Phillip B Oldham
phillip.old...@gmail.com wrote:

I've been taking a look at the multitude of coroutine libraries
available for Python, but from the looks of the projects they all seem
to be rather quiet. I'd like to pick one up to use on a current
project but can't deduce which is the most popular/has the largest
community.

Libraries I looked at include: cogen, weightless, eventlet and
circuits (which isn't exactly coroutine-based but it's event-driven
model was intriguing).

Firstly, are there any others I've missed? And what would the
consensus be on the which has the most active community behind it?
--
http://mail.python.org/mailman/listinfo/python-list


Coroutines are built into the language.  There's a good talk about
them here: http://www.dabeaz.com/coroutines/


But what some Python programmers call coroutines aren't really the same 
as what the programming community at large would call a coroutine.


Jean-Paul
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Re: Twisted 100% event driven or hybrid?


On 05:48 pm, mcfle...@vrplumber.com wrote:

exar...@twistedmatrix.com wrote:

On 05:55 am, jacopo.pe...@gmail.com wrote:

...
results to be ready, I collect and process them. From now on I don 
19t

need a the system to be event drive any more, the processing should
occur only on the master machine, following a deterministic flow.
As soon as finished I am ready to start again to resubmit the models
for recalculation and so on. This should go on forever.


Jean-Paul is obviously far more authoritative on the twisted way than
I am, so if he says you can just run your synchronous operation in- 
situ,

that's probably the way to go, but IIRC there's a
reactor.deferToThread() function which can run your synchronous code
off to the side, while allowing the twisted code to continue to
process incoming operations.  Thus you'd do something like:

def process( dataset ):
   dl = [ remote_call( x ) for x in dataset]
   dl = defer.DeferredList( dl )
   def on_all_results( results ):
   reactor.deferToThread( sync_process, (results,)).addCallback(
process )
   return dl.addCallback( on_all_results )

(I'm typing all of that from the distance of a few years of memory
decay, so take it as loosely this, with the proper function names and
the like).  Threads aren't really part of the twisted way in my
understanding, but they can be used if necessary AFAIK, and they will
let your application remain responsive to network events during the
processing.


Yep, you're correct here Mike (except it's 
`twisted.internet.defer.deferToThread` rather than 
`twisted.internet.reactor.deferToThread`).  If it is safe to call 
`sync_process` in a thread, then this may be a good approach as well, 
and it will free up the reactor to continue to respond to events 
(assuming `sync_process` plays nicely - ie, is written in Python or is 
an extension that releases the GIL, of course).


In my post, I was trying to highlight the idea that there's not really 
anything special going on in a Twisted program.  You can choose to block 
if you wish, if the consequences (events go unserviced for a while) are 
acceptable to you.


Jean-Paul
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Re: Solved - Python: automate input to MySQL query

2009-09-23 Thread Joe Riopel

On Wed, Sep 23, 2009 at 10:49 AM, D'Arcy J.M. Cain da...@druid.net wrote:
 Of course you can get around this by specifying every field and using
 AS to change the names to manager_id and employee_firstname, etc. but
 if you are going to do that anyway, why not just do it once in the
 database instead of littering the code?

In my case, I sometimes generate entity classes from automatically
from the database. So, I am not typing them, but the field names on
some of my classes will be longer than they need to be.  Also, I only
have to use the AS when I am doing joins, which I don't do as often as
selects, inserts, and/or updates. So now I would have to type the long
redundant column name for those 3 types of queries, instead of saving
me from typing AS in the joins.
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Searching Dictionary

2009-09-23 Thread Support Desk

i am trying to search a large Python dictionary for a matching value. The
results would need to be structured into a new dictionary with the same
structure. Thanks.

The structure is like this

{ Key : [{'item':value,'item2':value,'
item3':value,'item4':value,'item5':value','item6':value,'item7':value,'item8':value,'item9':value}],
Key2 :
[{'item':value,'item2':value,'item3':value,'item4':value,'item5':value','item6':value,'item7':value,'item8':value,'item9':value}],
Key3 :
[{'item':value,'item2':value,'item3':value,'item4':value,'item5':value','item6':value,'item7':value,'item8':value,'item9':value}]
}
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Re: easy question, how to double a variable

2009-09-23 Thread David C Ullrich

On Tue, 22 Sep 2009 02:34:53 +, Steven D'Aprano wrote:

 On Mon, 21 Sep 2009 13:50:23 -0500, David C Ullrich wrote:
 
 But you actually want to return twice the value. I don't see how to do
 that.
 
 What?
 
 Seriously? 

You're saying it _can_ be done in Python? They must have added
something to the standard library again. I mean how can you return
twice a value without a twice function to start with? I've tried.
You'd think

def twice(n):
  return twice(n)

would work, but I get this really long error message.

 You're not just yanking the OP's chain???

That would be cruel. I mean the guy has enough problems already...




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Idiom for last word in a string

2009-09-23 Thread Grant Edwards

I recently ran across this construct for grabbing the last
(whitespace delimited) word in a string:

   s.rsplit(None,1)[1]

It was somewhat obvious from the context what it was supposed
to do, but it took a bit of Googling to figure out exactly what
was going on.

When I want the last word in a string, I've always done this:

   s.split()[-1]

I was wondering what the advantage of the rsplit(None,1)[1]
approach would be other than inducing people to learn about the
maxsplit argument that is accepted by the split() methods?

-- 
Grant Edwards   grante Yow! I want a VEGETARIAN
  at   BURRITO to go ... with
   visi.comEXTRA MSG!!
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Re: Get error message from FTPLib

2009-09-23 Thread Jeff McNeil

On Sep 23, 1:46 pm, Bakes ba...@ymail.com wrote:
 I am using ftplib for a project, using a try/except loop.

 I would like to find out the exception, but I am a python newbie and
 do not know how.

 How, in a try/except loop would I find the ftplib exception?


For a bit on exception handling in general, check out the section
within the Python tutorial: http://docs.python.org/tutorial/errors.html.
As far as the ftplib module goes, it has an attribute named
'all_errors.' It's a tuple that contains all of the Exception types
that ftplib.FTP methods will throw. You can do something like the
following:

try:
   FTP_instance.do_something()
except ftplib.all_errors, e:
   handle_an_error(e)

I do something much like that in an NMS-like application I wrote.

--
Thanks,

Jeff
mcjeff.blogspot.com

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Re: Idiom for last word in a string

On Sep 23, 2:47 pm, Grant Edwards inva...@invalid.invalid wrote:
 I recently ran across this construct for grabbing the last
 (whitespace delimited) word in a string:

    s.rsplit(None,1)[1]

 It was somewhat obvious from the context what it was supposed
 to do, but it took a bit of Googling to figure out exactly what
 was going on.

 When I want the last word in a string, I've always done this:

    s.split()[-1]

 I was wondering what the advantage of the rsplit(None,1)[1]
 approach would be other than inducing people to learn about the
 maxsplit argument that is accepted by the split() methods?

 --
 Grant Edwards                   grante             Yow! I want a VEGETARIAN
                                   at               BURRITO to go ... with
                                visi.com            EXTRA MSG!!

hello,
perhaps rsplit generates as many elements in the list as absolutely
necesary compared to the whole list returned by split()?
konstantin
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Open file on remote linux server

2009-09-23 Thread The Bear


Hi I'm looking to do something like this

f = f.openfileobj(remotefileloc, localfilelikeobj)

my remote files are on a solaris box that i can access using ssh (could
prehap request othe protocols if necessary)

anyone got any ideas?

many thanks

Charlie

(ps. tried this on the python-forum but didn't seem to go on so apologies if
i'm cross posting)
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Querying for ownership of file shared by Samba fails with MemoryError: allocating SECURITY_DESCRIPTOR

2009-09-23 Thread Middle Fork GIS

I have just learned how to use the win32security module (within Windows, of
course) to determine file ownership.  When running against local drives or
windows shares, this works fine, as shown in the following code (Python
2.4/2.5 with PyWin extensions):

import win32security
file = 'c:/temp/test.txt'
#Using the win32security module get ownership information
ownerSecurity=
win32security.GetFileSecurity(file,win32security.OWNER_SECURITY_INFORMATION)
ownerSID = ownerSecurity.GetSecurityDescriptorOwner ()
owner,domain,type = win32security.LookupAccountSid (None, ownerSID)
print File %s is owned by %s\\%s % (file,domain,owner)


However, when I run this against a file on an SMB mounted file system (the
server is AIX Unix),the following error is raised:


File
C:\Python24\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py,
line 325, in RunScript
exec codeObject in __main__.__dict__

File C:\scripts\testfileinfo.py, line 17, in ?
ownerSecurity=
win32security.GetFileSecurity(file,win32security.OWNER_SECURITY_INFORMATION)

MemoryError: allocating SECURITY_DESCRIPTOR



Interestingly, searching the G**gle for the string
MemoryError: allocating SECURITY_DESCRIPTOR results in only two primary
hits, back to 2003, which look like this:

 Anyone have any ideas on what the problem might be here (M: is a
 Win98 shared disk space - command was issued from a PythonWin
 session running on a Win 2000 machine):

  GetFileSecurity(M:\\autoexec.bat, OWNER_SECURITY_INFORMATION)
 Traceback (most recent call last):
 File interactive input, line 1, in ?
 MemoryError: allocating SECURITY_DESCRIPTOR

Win95,98,ME use the FAT32 filesystem. This has absolutely no ACL or
permission capabilities on it. Win NT, 2K, XP use NTFS by default,
which allows ACLS.

Any insights would be greatly appreciated.

Steve Walker
middleforkgis aht gmail.com
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Re: Idiom for last word in a string

At Wed, 23 Sep 2009 18:47:05 + (UTC),
Grant Edwards wrote:
 
 I recently ran across this construct for grabbing the last
 (whitespace delimited) word in a string:
 
s.rsplit(None,1)[1]
 
 It was somewhat obvious from the context what it was supposed
 to do, but it took a bit of Googling to figure out exactly what
 was going on.
 
 When I want the last word in a string, I've always done this:
 
s.split()[-1]
 
 I was wondering what the advantage of the rsplit(None,1)[1]
 approach would be other than inducing people to learn about the
 maxsplit argument that is accepted by the split() methods?
 

s.rsplit(None, 1) is a cheaper operation because it splits the string
*only once*.
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Re: Idiom for last word in a string

At Wed, 23 Sep 2009 18:47:05 + (UTC),
Grant Edwards wrote:
 
 I recently ran across this construct for grabbing the last
 (whitespace delimited) word in a string:
 
s.rsplit(None,1)[1]
 
 It was somewhat obvious from the context what it was supposed
 to do, but it took a bit of Googling to figure out exactly what
 was going on.
 
 When I want the last word in a string, I've always done this:
 
s.split()[-1]
 
 I was wondering what the advantage of the rsplit(None,1)[1]
 approach would be other than inducing people to learn about the
 maxsplit argument that is accepted by the split() methods?
 

s.rsplit(None, 1) is a cheaper operation because it splits the string
*only once*.
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Re: Idiom for last word in a string

At Wed, 23 Sep 2009 18:47:05 + (UTC),
Grant Edwards wrote:
 
 I recently ran across this construct for grabbing the last
 (whitespace delimited) word in a string:
 
s.rsplit(None,1)[1]
 
 It was somewhat obvious from the context what it was supposed
 to do, but it took a bit of Googling to figure out exactly what
 was going on.
 
 When I want the last word in a string, I've always done this:
 
s.split()[-1]
 
 I was wondering what the advantage of the rsplit(None,1)[1]
 approach would be other than inducing people to learn about the
 maxsplit argument that is accepted by the split() methods?
 

s.rsplit(None, 1) is a cheaper operation because it splits the string
*only once*.
-- 
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Re: Idiom for last word in a string

At Wed, 23 Sep 2009 18:47:05 + (UTC),
Grant Edwards wrote:

 I recently ran across this construct for grabbing the last
 (whitespace delimited) word in a string:

s.rsplit(None,1)[1]

 It was somewhat obvious from the context what it was supposed
 to do, but it took a bit of Googling to figure out exactly what
 was going on.

 When I want the last word in a string, I've always done this:

s.split()[-1]

 I was wondering what the advantage of the rsplit(None,1)[1]
 approach would be other than inducing people to learn about the
 maxsplit argument that is accepted by the split() methods?


s.rsplit(None, 1) is a cheaper operation because it splits the string
*only once*.
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Re: pygui - showing an image

2009-09-23 Thread kyle schalm

yes, that did the trick. i was not aware of all the examples in Test,
only the three Demo projects. thanks!

2009/9/22 David Robinow drobi...@gmail.com:
 There's an example in Tests/21-image.py
 See if that helps.

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pycopg2 build problems

2009-09-23 Thread devaru

Hi,

I'm trying to install psycopg2 on my system. I followed the
instruction in INSTALL file and gave the command
python setup.py build
running build
running build_py
running build_ext
error: No such file or directory

Where is the file or directory missing. Any help is appreciated.
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Re: Idiom for last word in a string

2009-09-23 Thread Peter Otten

akonsu wrote:

 On Sep 23, 2:47 pm, Grant Edwards inva...@invalid.invalid wrote:
 I recently ran across this construct for grabbing the last
 (whitespace delimited) word in a string:

 s.rsplit(None,1)[1]

 It was somewhat obvious from the context what it was supposed
 to do, but it took a bit of Googling to figure out exactly what
 was going on.

 When I want the last word in a string, I've always done this:

 s.split()[-1]

 I was wondering what the advantage of the rsplit(None,1)[1]
 approach would be other than inducing people to learn about the
 maxsplit argument that is accepted by the split() methods?

 --
 Grant Edwards   grante Yow! I want a
 VEGETARIAN at   BURRITO to go ... with
 visi.comEXTRA MSG!!
 
 hello,
 perhaps rsplit generates as many elements in the list as absolutely
 necesary compared to the whole list returned by split()?
 konstantin

Indeed, and if the string is long it has a measurable effect:

$ python -m timeit -ss = 'oneword '*1000 s.rsplit(None, 1)[-1]
10 loops, best of 3: 2.23 usec per loop
$ python -m timeit -ss = 'oneword '*1000 s.split()[-1]
1000 loops, best of 3: 191 usec per loop

Peter

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Re: custom data warehouse in python vs. out-of-the-box ETL tool

2009-09-23 Thread Martin P. Hellwig


snfctech wrote:

@Martin:  I originally thought that there was nothing magical about
building a data warehouse, but then I did a little research and
received all sorts of feedback about how data warehouse projects have
notorious failure rates, that data warehouse design IS different than
normal RDBMS - and then there's the whole thing about data marts vs.
warehouses, Kimball vs. Inmon, star schemas, EAV tables, and so on.
So I started to think that maybe I needed to get a little better read
on the subject.


Yes failure rate for data warehouse projects is quite high, so are other 
IT projects without data warehouses.


Data warehouse design is not that much different than 'normal' RDBMS,
you are following the same decisions for example:
- Do I rather have multiple copies of data than slow or complicated 
access? If yes how do I ensure integrity?

- How do I do access control on value level?
- Do I need fail over or load balancing, if yes how much of it can I do 
on the application level?


The thing is if you never have designed a database from a database point 
of view because you used abstractions that hide these ugly details then 
yes, Data warehouses are different than normal RDBMS.


Yes you can make it all sound very complicated by throwing PHB words in 
like meta schema's, dimensional approach, subject orientated, etc.
I like to see it more like I have a couple of data sources, I want to 
combine them  in a way that I can do neat stuff with it. The 'combine 
them' part is the data warehouse design, the 'neat stuff' part are the 
clients that use that data warehouse. If you wish you can start making 
it more complicated by saying but my data sources are also my clients, 
but that is another step.


I guess you can sum up all this by saying a data warehouse is a method 
of gathering already existing data and present them in a different way, 
the concept is simple, the details can be complicated if you want/need 
it to be.


--
MPH
http://blog.dcuktec.com
'If consumed, best digested with added seasoning to own preference.'
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Re: pycopg2 build problems

2009-09-23 Thread Philip Semanchuk



On Sep 23, 2009, at 3:24 PM, devaru wrote:


Hi,

I'm trying to install psycopg2 on my system. I followed the
instruction in INSTALL file and gave the command
python setup.py build
running build
running build_py
running build_ext
error: No such file or directory

Where is the file or directory missing. Any help is appreciated.



Try asking on the psycopg2 mailing list.


Good luck
Philip
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Re: Open file on remote linux server

2009-09-23 Thread Sean DiZazzo

On Sep 23, 12:04 pm, The Bear c.poll...@bangor.ac.uk wrote:
 Hi I'm looking to do something like this

 f = f.openfileobj(remotefileloc, localfilelikeobj)

 my remote files are on a solaris box that i can access using ssh (could
 prehap request othe protocols if necessary)

 anyone got any ideas?

 many thanks

 Charlie

 (ps. tried this on the python-forum but didn't seem to go on so apologies if
 i'm cross posting)
 --
 View this message in 
 context:http://www.nabble.com/Open-file-on-remote-linux-server-tp25531253p255...
 Sent from the Python - python-list mailing list archive at Nabble.com.

I don't know of any Python library that will give you that kind of
access to a remote file over ssh.  It sounds like a fun project
though!

If nothing else, you can install the ssh filesystem for Fuse, and just
mount the remote filesystem as if it was local.

~Sean
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Re: Searching a large dictionary

2009-09-23 Thread mike171562

i am trying to search a large Python dictionary for a matching value.
The results would need to be structured into a new dictionary with the
same structure. Thanks.

The structure is like this

{ Key : [{'item':value,'item2':value,'
item3':value,'item4':value,'item5':value','item6':value,'item7':value,'item8':value,'item9':value}],
Key2 :
[{'item':value,'item2':value,'item3':value,'item4':value,'item5':value','item6':value,'item7':value,'item8':value,'item9':value}],
Key3 :
[{'item':value,'item2':value,'item3':value,'item4':value,'item5':value','item6':value,'item7':value,'item8':value,'item9':value}]
}

On Sep 22, 7:16 pm, Dave Angel da...@ieee.org wrote:
Support Desk wrote:
I need help searching a large python dictionary. The dictionary is setup
like so

Key[{'item':value,'item2':value,'item3':value,'item4':value,'item5':value','item6':value,'item7':value,'item8':value,'item9':value}]

Key2[{'item':value,'item2':value,'item3':value,'item4':value,'item5':value','item6':value,'item7':value,'item8':value,'item9':value}]

Key3[{'item':value,'item2':value,'item3':value,'item4':value,'item5':value','item6':value,'item7':value,'item8':value,'item9':value}]

What would be the best way to search for a specific value of item1 and add
all the results to a new dictionary? Thanks

With all the messages I've seen so far on this thread, all you've
managed to do is confuse it further. I suggest you start over (new
thread) with a legal program defining a single dictionary (with real
values for Key, Key2, and value, and without extra quote marks which
make it fail to compile even if we guess what you're doing with the
three keys). I suggest that at least some relevant parts of the data
should not be all identical, so we can tell what's important.

Use copy paste from working code.

Then given a real dictionary, describe what you really want to search
for, and what acceptable results would be.

And also specify the programming language, version, and OS environment.

Thanks.
DaveA

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Re: arrays in python

On Wed, Sep 23, 2009 at 1:14 PM, Rudolf yellowblueyel...@gmail.com wrote:
 Can someone tell me how to allocate single and multidimensional arrays
 in python. I looked online and it says to do the following x =
 ['1','2','3','4']

 However, I want a much larger array like a 100 elements, so I cant
 possibly do that. I want to allocate an array and then populate it
 using a for loop. Thanks for your help.
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 http://mail.python.org/mailman/listinfo/python-list


In python they're called 'lists'.  There are C-style array objects but
you don't want to use them unless you specifically have to.

You can create an empty list like so:

x = []

and then put items into it with a for loop like so:

for item in some_iterable:
x.append(item)

But in simple cases like this there's also the list comprehension
syntax which will do it all in one step:

x = [item for item in some_iterable]

But again in a case like this, if you're simply populating a list from
an iterable source you would just say:

x = list(some_iterable)

For multidimensional 'arrays' you just put lists in lists.  (Or use
NumPy if you really want arrays and are doing lots of wild processing
on them.)

But if you do this:

two_dimensional_list = [ [] for var in some_iterable]

The list of lists you create thereby will contain multiple references
to the /same/ inner list object.  This is something that catches many
people unawares.  You have to go back to using a for loop:

x = []
for n in range(100):
x.append([(n, m) for m in range(10)])

(That will create a list of one hundred lists, each of which contains
ten tuples.)

Good luck.
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Re: arrays in python

On Wed, Sep 23, 2009 at 1:22 PM, Donn donn.in...@gmail.com wrote:
 On Wednesday 23 September 2009 19:14:20 Rudolf wrote:
 I want to allocate an array and then populate it
 using a for loop.
 You don't need to allocate anything, just use the list or dictionary types.

 l=[] #empty list
 for x in range(1,500):
  l.append(x)


Of course, in this example you could just say,

l = range(1,500)

Or in python 3,

l = list(range(1,500))
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Re: arrays in python

2009-09-23 Thread Ethan Furman


Donn wrote:

On Wednesday 23 September 2009 19:14:20 Rudolf wrote:


I want to allocate an array and then populate it
using a for loop. 


You don't need to allocate anything, just use the list or dictionary types.

l=[] #empty list
for x in range(1,500):
 l.append(x)

\d


Works great if you want 4,999,999 elements.  ;-)  Omit the '1' if you 
want all five million.


~Ethan~
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Re: Most active coroutine library project?