🌐 Mailman 3 January 2009 - Python-list - python.org

OpenOpt 0.21 (free optimization framework)
by dmitrey Jan. 1, 2009

Jan. 1, 2009

Hi all, OpenOpt 0.21, free optimization framework (license: BSD) with some own solvers and connections to tens of 3rd party ones, has been released. All details here: http://openopt.blogspot.com/2008/12/openopt-release-021.html Regards, OpenOpt developers.

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Re: type conversion
by Steven D'Aprano Jan. 1, 2009

Jan. 1, 2009

On Wed, 31 Dec 2008 12:35:20 -0800, Hamish McKenzie wrote: > sometimes I want to be able to initialize an instance with a variety of > different data types. Type conversion is a bit of a misleading subject line. You're not really converting different types, just initialising from different types. > as an obvious example I might want to initialize a 4x4 matrix with > either 16 floats, a list/tuple or 16 floats, another matrix or a > quaternion. > > is there any other way to do it other than putting case statements in > the __init__ method of the class, or having a Matrix.FromQuaternion( > quat )? You could have an external function qtom: def qtom(quaternion): a, b, c, d = quaternion return Matrix([ a, 0, 0, 0, 0, b, 0, 0, 0, 0, c, 0, 0, 0, 0, d]) But the first two solutions seem reasonable to me, except of course Python doesn't have a case statement you have to use an if...elseif block. -- Steven

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Desktop/File management support on MS Windows
by riklaunim＠gmail.com Jan. 1, 2009

Jan. 1, 2009

Are there any Python libraries that can trash files (move to Trash, not delete) or for example return a list of applications that can open given file? I can't find anything related to this for Windows.

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SQL, lite lite lite
by Aaron Brady Jan. 1, 2009

Jan. 1, 2009

Hi all, About a year ago, I posted an idea I was having about thread synchronization to the newsgroup. However, I did not explain it well, and I really erred on the side of brevity. (After some finagling, Mr. Bieber and I decided it wasn't exactly anything groundbreaking.) But I think the brevity cost me some readers, who might have had more interest. The affair was on the whole discouraging. So, I'm going to try another idea, and assume that readers have some time, and will spend it on it. I don't think relational data can be read and written very easily in Python. There are some options, such as 'sqllite3', but they are not easy. 'sqllite3' statements are valid SQL expressions, which afford the entire power of SQL, but contrary to its name, it is not that 'lite'. To me, 'lite' is something you could learn (even make!) in an afternoon, not a semester; something the size of an ActiveState recipe, or a little bigger, maybe a file or two. If you think SQL is a breeze, you probably won't find my idea exciting. I assume that the basics of SQL are creating tables, selecting records, and updating records. My idea is to create a 'Relation' class. The details are basically open, such as whether to back it with 'sqllite3', 'shelve', 'mmap', or just mapping and sequence objects; what the simplest syntax is that can capture and permit all the basics, and how much and what else can fit in at that level; how and whether it can include arbitrary Python objects, and what constraints there are on them if not; how and whether to permit transactions; and what the simplest and coolest thing you can do with a little Python syntax is. This is basically an invitation for everyone to brainstorm. (No hijackings, good humor & digression ok.) Lastly, ... **warning, spoiler! here's what I thought of already.** **repeat! spoiler! here's what I thought of already.** #Just the select and update syntax: >>> a= people._select( "firstname== 'Joe'" ) #select 'key' from 'people' where 'firstname'== 'joe' >>> a [Entry2864, Entry3076, Entry3172] >>> entry1= a[ 0 ] >>> entry1.phone #select 'phone' from 'people' where 'key'==self.key "555-2413" >>> entry1.phone= "555-1234" #update 'people' set 'phone'= '555-1234' where 'key'==self.key >>> entry1.phone "555-1234" #Create table syntax (a-whole-nother beast in itself): >>> classes= db.Relation( 'class_', 'person', Unique( 'class_', 'person' ) ) #create table 'classes' ( 'key', 'class_', 'person' ) unique ( 'class_', 'person' ) >>> classes._unique( 'class_', 'person' ) >>> classes.class_.noneok= False #'class_' cannot be null >>> classes.person.noneok= False >>> classes._insert( 'Physics', 'Dan' ) >>> classes._insert( 'Chem', 'Tim' ) Hoping-"good critic"-is-self-consistent-ly, hoping-to-hear-it's-too- complicated-already-ly, A. Brady

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Re: game engine (as in rules not graphics)
by Aaron Brady Jan. 1, 2009

Jan. 1, 2009

On Dec 29, 4:14 am, Martin <mar...(a)marcher.name> wrote: > Hi, > > 2008/12/29 Phil Runciman <ph...(a)aspexconsulting.co.nz>: > > > See: Chris Moss, Prolog++: The Power of Object-Oriented and Logic Programming (ISBN 0201565072) > > > This book is a pretty handy intro to an OO version Prolog produced by Logic Programming Associates. > > From: Aaron Brady [mailto:castiro...@gmail.com] > > Sent: Sunday, 28 December 2008 1:22 p.m. > > Not my expertise but here are my $0.02. You are looking for ways to represent rules: buying a house is legal in such and such situation, and the formula for calculating its price is something. You want "predicates" such as InJail, OwnedBy, Costs. > > > Costs( New York Ave, 200 ) > > InJail( player2 ) > > OwnedBy( St. Charles Ave, player4 ) > > LegalMove( rolldie ) > > LegalMove( sellhouse ) > > I'm not sure I'm looking for prolog, i had an introductory course back > at the university but it didn't exactly like it. I'm after some info > how such rules would defined in python (specifically python althou > logic programming is probably the more appropriate way). > > I guess I'm missing quite some basics in the design of such concepts, > I'll head back to google to find some introductory stuff now :). snip It depends on what you want to do with it. Do you want to answer a question about whether something is legal? Do you want a catalog of legal moves? Do you want to forward-chain moves to a state? Do you want just a representation for its own sake? For instance, the game just started. Player 1 landed on Oriental, bought it, and Player 2 landed in the same place. Here are the legal possibilities. Player 1 offers to sell Oriental to Player X. Player X offers to buy Oriental from Player 1. Player 1 mortgages Oriental. Player 1 collects rent from Player 2. Player 3 rolls dice. Thinking aloud, I think the closest thing to predicates you'll have in Python is to build a Relation class or use a relational database. Some tables you might use are: Property( id, name, price, rent0houses, rent1house, ..., numhouses, mortgaged, owner ). Player( id, location, money ). LastMove( player.id ). P.S. There is 'pyprolog' on sourceforge; I did not check it out.

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Re: If your were going to program a game...
by Fuzzyman Jan. 1, 2009

Jan. 1, 2009

On Jan 1, 8:55 pm, "Chris Rebert" <c...(a)rebertia.com> wrote: > On Thu, Jan 1, 2009 at 12:24 PM, excord80 <excor...(a)gmail.com> wrote: > > On Jan 1, 2:37 pm, Kay Schluehr <kay.schlu...(a)gmx.net> wrote: > > >> There is no solution to this problem from a Python perspective. Do > >> what everyone does right now: [snip] > > > It still surprises me that no one has implemented the solution for > > this yet. > > > Maybe it's harder than it seems, but it *seeems* like it's just a > > matter of telling Firefox, "hey, when you see this special html > > element that tells you to run this python code from the web, do it". > > Then have FF load up a python interpreter, sandbox it somehow (that > > is, limit it to only a safe subset of its std lib), it runs the code > > The "sandbox it somehow" part is significantly harder than you seem to > believe it would be. Python tried previously with the rexec and > Bastion modules, but they were found to be irreparably flawed and thus > were removed. > However, Google App Engine seems to have found at least a partial > solution, but they're keeping it to themselves as far as I know, and > it's server-side rather than client-side anyway. > PyPy allows *true* sandboxing, as does IronPython through AppDomains. I wouldn't recommend either for 'in the browser' use though. You can do client side programming in the browser with Silverlight. It's great fun to program, and very flexible, but limited to Safari, IE & Firefox on Mac and Windows. Moonlight is making good progress which will bring Silverlight to Firefox on Linux - and eventually more browsers and platforms. Michael Foord -- http://www.ironpythoninaction.com/

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Is this a bug in Python or something I do not understand.
by davidalvi＠gmail.com Jan. 1, 2009

Jan. 1, 2009

Consider these two lists comprehensions: L1=[[1 for j in range(3)] for i in range(3)] L2=[[1]*3]*3 print L1 print L2 print L1==L2 The result is: [[1, 1, 1], [1, 1, 1], [1, 1, 1]] [[1, 1, 1], [1, 1, 1], [1, 1, 1]] True So far, everything is OK, but let us now modify the lists' contents in the following way: for i in range(3): for j in range(3): if j<i: L1[i][j]=0 L2[i][j]=0 print L1 print L2 print L1==L2 The output is now: [[1, 1, 1], [0, 1, 1], [0, 0, 1]] [[0, 0, 1], [0, 0, 1], [0, 0, 1]] False It seems a misbehaviour in Python, or there is something I do not understand in the syntax ????

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Release of PyGreSQL 4.0
by D'Arcy J.M. Cain Jan. 1, 2009

Jan. 1, 2009

We are please to announce the release of PyGreSQL 4.0. his is a major release and you should check it carefully before using in existing applications. There may be some incompatibilities. PyGreSQL is a Python module that interfaces to a PostgreSQL database. It embeds the PostgreSQL query library to allow easy use of the powerful PostgreSQL features from a Python script. For more information, please visit http://www.PyGreSQL.org/. >From the changelog: - Dropped support for Python below 2.3 and PostgreSQL below 7.4. - Improved performance of fetchall() for large result sets by speeding up the type casts (as suggested by Peter Schuller). - Exposed exceptions as attributes of the connection object. - Exposed connection as attribute of the cursor object. - Cursors now support the iteration protocol. - Added new method to get parameter settings. - Added customizable row_factory as suggested by Simon Pamies. - Separated between mandatory and additional type objects. - Added keyword args to insert, update and delete methods. - Added exception handling for direct copy. - Release the GIL while making a connection (as suggested by Peter Schuller). - If available, use decimal.Decimal for numeric types. - Allow DB wrapper to be used with DB-API 2 connections (as suggested by Chris Hilton). - Made private attributes of DB wrapper accessible. - Dropped dependence on mx.DateTime module. - Support for PQescapeStringConn() and PQescapeByteaConn(); these are now also used by the internal _quote() functions. - Added 'int8' to INTEGER types. New SMALLINT type. - Added a way to find the number of rows affected by a query() with the classic pg module by returning it as a string. For single inserts, query() still returns the oid as an integer. The pgdb module already provides the "rowcount" cursor attribute for the same purpose. - Improved getnotify() by calling PQconsumeInput() instead of submitting an empty command. - Removed compatibility code for old OID munging style. - The insert() and update() methods now use the "returning" clause if possible to get all changed values, and they also check in advance whether a subsequent select is possible, so that ongoing transactions won't break if there is no select privilege. - Added "protocol_version" and "server_version" attributes. - Revived the "user" attribute. - The pg module now works correctly with composite primary keys; these are represented as frozensets. - Removed the undocumented and actually unnecessary "view" parameter from the get() method. - get() raises a nicer ProgrammingError instead of a KeyError if no primary key was found. - delete() now also works based on the primary key if no oid available and returns whether the row existed or not. -- D'Arcy J.M. Cain PyGreSQL Development Group http://www.PyGreSQL.org

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Chart libs for python
by Mir Nazim Jan. 1, 2009

Jan. 1, 2009

Hi guys, Please suggest me chart generation library for python comparable to google chart in features and ease of development. Google Chart has a limitation on amount on data you can send in a URL. Thanks

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Re: How to run Python in Windows w/o popping a DOS box?
by GeertVc Jan. 1, 2009

Jan. 1, 2009

On Jan 1, 7:05 pm, Geert Vancompernolle <geert.discussi...(a)gmail.com> wrote: > I know it's been a long while since this thread has been handled, but > maybe this is a "final" solution to your problem (if not yet resolved): > > http://www.py2exe.org/index.cgi/SingleFileExecutable > > Especially the last setup.py file results in only one exe which contains > *all* the necessary stuff (only tested it on small examples, though) > > Maybe you can give this a try... > > Best rgds, > --Geert > * > * Might seem an "odd" posting at first, but I wanted to reply on a (quite) old thread: http://groups.google.com/group/comp.lang.python/browse_thread/thread/456bc0… I couldn't reply any more on that one, so... Best rgds, --Geert

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