Re: Why are there no ordered dictionaries?
[EMAIL PROTECTED] wrote: > Fredrik Lundh wrote: > > but you can easily generate an index when you need it: > > > > index = dict(d) > > > > name, type = index["pid"] > > print name > > > > the index should take less than a microsecond to create, and since it > > points to the members of the original dict, it doesn't use much memory > > either... > > > Using the same logic, we don't need types other than string in a DBMS > as we can always convert a string field into some other types when it > is needed. No, that's not the same logic. The dict() in my example doesn't convert be- tween data types; it provides a new way to view an existing data structure. There's no parsing involved, nor any type guessing. And given the use case, it's more than fast enough, and doesn't copy any data. If you think that's the same thing as parsing strings, you've completely missed the point. -- http://mail.python.org/mailman/listinfo/python-list
Re: setattr for secondary attribute
Alex wrote: > I apologize for asking maybe a very trivial question. > I have a new class object A with slots. One of the slots is, for > example, object spam. Object spam, in turn, also has slots and one of > them is attribute eggs. I need to assign a new value to eggs. In other > words, I need to perform the following: > > A.spam.eggs=newValue > > The problem is that I have only a string s='spam.eggs' with which to > work, so I cannot write an expression written above. I tried to use > setattr: > > setattr(A, s, newValue) > > but this does not work. It says that object A does not have attribute > spam.eggs since "eggs" is an attribute of the "spam" attribute, you need to fetch the latter first: setattr(getattr(A, "spam"), "eggs") -- http://mail.python.org/mailman/listinfo/python-list
Re: ownership problem?
Jeffrey Schwab wrote: > > the problem isn't determining who owns it, the problem is determining > > who's supposed to release it. that's not a very common problem in a > > garbage-collected language... > > Yes it is. Memory is only one type of resource. Python's garbage collector deals with objects, not memory. > I am not a Python Guru from the sound of it, you haven't written serious programs in any of the languages you mention. -- http://mail.python.org/mailman/listinfo/python-list
Re: Aproximative string matching
"javuchi" <[EMAIL PROTECTED]> wrote: > >I'm searching for a library which makes aproximative string matching, >for example, searching in a dictionary the word "motorcycle", but >returns similar strings like "motorcicle". > >Is there such a library? There is an algorithm called Soundex that replaces each word by a 4-character string, such that all words that are pronounced similarly encode to the same string. The algorithm is easy to implement; you can probably find one by Googling. -- - Tim Roberts, [EMAIL PROTECTED] Providenza & Boekelheide, Inc. -- http://mail.python.org/mailman/listinfo/python-list
Re: BaseHTTPServer module
"amfr" <[EMAIL PROTECTED]> wrote: > >>From the BaseHTTPServer module, how do i gget the POST or GET data sent >by the client? Is it stired the the file they requested? e.g. >objectname.path Did you check the documentation in the module? You need to derive your own class from BaseHTTPServer. In that module, you need to add functions called do_GET and do_POST. In a GET request, the data is all encoded in the URL. You'll find that in self.path. In a POST request, the data is all encoded in the body of the request. You'll find that in self.rfile. You'll have to parse and decode it yourself. However, as the module documentation also tells you, that has already been done for you in SimpleHTTPServer.py. -- - Tim Roberts, [EMAIL PROTECTED] Providenza & Boekelheide, Inc. -- http://mail.python.org/mailman/listinfo/python-list
about dictionary
>>> b=dict.fromkeys(a) -- http://mail.python.org/mailman/listinfo/python-list
Re: Problem printing in Win98
"Maravilloso" <[EMAIL PROTECTED]> wrote: > >I'm trying to automatically send a postscript file to be printed to the >default printer in a Win98 PC, by means of using the instrucction: > > win32api.ShellExecute (0, "print", "file.ps", None, ".", 0) > >but it raises an exception with the message: > > error: (31, 'ShellExecute', 'A device attached to the system is not >functioning.') Roger is correct. In order to print a .ps file, you have to have installed an application that handles .ps files. You have probably installed GhostScript on your 2K/XP box. If you install it on your Win98 box, your ShellExecute should work. -- - Tim Roberts, [EMAIL PROTECTED] Providenza & Boekelheide, Inc. -- http://mail.python.org/mailman/listinfo/python-list
Re: check if com api is still available
Neil Hodgson <[EMAIL PROTECTED]> wrote: > >All running COM servers should be in the "Running Object Table" >(ROT). If you search the net for this term you will find code that can >show what is in the ROT, so there must be an API. If only. The Microsoft Office applications seem to be the only ones in the world that use the ROT. -- - Tim Roberts, [EMAIL PROTECTED] Providenza & Boekelheide, Inc. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python under Citrix Metaframe
"Xaver Hinterhuber" <[EMAIL PROTECTED]> wrote: > >I wanted to use python under Citrix Metaframe. >After installation of the ActivePython 2.4.1 msi-File, printing under Citrix >Metaframe no longer worked. That seems incredible unlikely. Are you talking about printing to a printer on the server, or printing to a printer on the local machine? Did you change to "/install" mode to do the installation, and then switch back to "/execute" mode? Printing to a local printer under Citrix is always a pain in the rear, but Python doesn't have anything to do with that. >Do you use python under Citrix Metaframe? >What problems did you encounter? I've used Python extensively with Microsoft's Terminal Services. -- - Tim Roberts, [EMAIL PROTECTED] Providenza & Boekelheide, Inc. -- http://mail.python.org/mailman/listinfo/python-list
Re: best cumulative sum
Erik Max Francis wrote: > Micah Elliott wrote: > > > On Nov 21, David Isaac wrote: > > > >> What's the good way to produce a cumulative sum? > > > import operator > x = 1,2,3 > reduce(operator.add, x) > > 6 > > Or just sum(x). > He seems to want scanl -- http://mail.python.org/mailman/listinfo/python-list
Re: Underscores in Python numbers
Peter Hansen>Or maybe one should instead interpret this as "numeric literals need more bells and whistles, and I don't care which of these two we add, but we have to do *something*!". :-) The purpose of my words was: when you think about adding a new syntax/functionality to a language, you have to think well if the same syntax can be used for something more important or more natural for it, so later you can avoid later problems and silly compromises. Bye, bearophile -- http://mail.python.org/mailman/listinfo/python-list
Re: best cumulative sum
Erik Max Francis wrote: > Micah Elliott wrote: > >>On Nov 21, David Isaac wrote: >>>What's the good way to produce a cumulative sum? >> >import operator >x = 1,2,3 >reduce(operator.add, x) >> >>6 > > Or just sum(x). That just gives you the tail end. The OP asked for a cumulative sum; that is, a list with all of the intermediate sums, too. -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: ownership problem?
Yes! Python uses auto garbage collection. As soon as the object reference count becomes 0 it is removed from existence. So the problem typical for C/C++: accessing pointers to already deleted objects does not exist in Python. -- http://mail.python.org/mailman/listinfo/python-list
Re: best cumulative sum
Micah Elliott wrote: > On Nov 21, David Isaac wrote: > >> What's the good way to produce a cumulative sum? > import operator x = 1,2,3 reduce(operator.add, x) > 6 Or just sum(x). -- Erik Max Francis && [EMAIL PROTECTED] && http://www.alcyone.com/max/ San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis Never contend with a man who has nothing to lose. -- Baltasar Gracian -- http://mail.python.org/mailman/listinfo/python-list
Re: best cumulative sum
On Nov 21, David Isaac wrote: > What's the good way to produce a cumulative sum? >>> import operator >>> x = 1,2,3 >>> reduce(operator.add, x) 6 -- _ _ ___ |V|icah |- lliott <>< [EMAIL PROTECTED] " " """ -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Ben Finney wrote: > [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > [sort by] some other metadata that is not present in the data. > > [...] > > Of course, you may say, just put another column that represent > > this(some reporting programs I have seen do it this way) and that is > > an option but not the only option. > > It's a pretty good option, and very commonly used. It's known as the > "Schwartzian transform", or more descriptively, the "Decorate, Sort, > Undecorate" pattern. > Whether it is a good option is judged by the person implement it as he is the one seeing the whole thing, and not some snippet(or concept) on the usenet. -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
[EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > [sort by] some other metadata that is not present in the data. > [...] > Of course, you may say, just put another column that represent > this(some reporting programs I have seen do it this way) and that is > an option but not the only option. It's a pretty good option, and very commonly used. It's known as the "Schwartzian transform", or more descriptively, the "Decorate, Sort, Undecorate" pattern. http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52234> -- \ "Experience is that marvelous thing that enables you to | `\ recognize a mistake when you make it again." -- Franklin P. | _o__)Jones | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
[ANN] Python API InformixDB-2.1 released
Hi everybody: I am proud to announce a new release of InformixDB, the IBM Informix implementation of the Python DB API. This release adds the following new features: * Scroll cursors and cursors with hold * Support for INTERVAL types * Support for Smart Large Objects * Support for User Defined Types Downloads and more info at http://informixdb.sourceforge.net/ Enjoy, Carsten Haese. -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Bengt Richter wrote: > On Sun, 20 Nov 2005 22:03:34 +0100, Christoph Zwerschke <[EMAIL PROTECTED]> > wrote: > >> Ordering the keys isn't the normal case, and can be done easily when > >> needed. > > > >That depends. Maybe I do not want the keys to be sorted alphabetically, > >but according to some criteria which cannot be derived from the keys > >themselves. > You mean involving also the values? What's wrong with > sorted(plaindict.items(), key=your_ordering_function) ? > Not according to the content of the data, not just the "key". Or in other words, some other metadata that is not present in the data. A typical thing, like order of creation. Or some arbitary order. For example : I present a data grid/table in a HTML form and the user just drag and drop and rearrange the columns order. Of course, you may say, just put another column that represent this(some reporting programs I have seen do it this way) and that is an option but not the only option. -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
On Sun, 20 Nov 2005 22:03:34 +0100, Christoph Zwerschke <[EMAIL PROTECTED]>
wrote:
>> Ordering the keys isn't the normal case, and can be done easily when
>> needed.
>
>That depends. Maybe I do not want the keys to be sorted alphabetically,
>but according to some criteria which cannot be derived from the keys
>themselves.
You mean involving also the values? What's wrong with
sorted(plaindict.items(), key=your_ordering_function) ?
>>> def show(*a): print a
...
>>> sorted(dict((c,ord(c)) for c in 'abcd').items(), key=show)
(('a', 97),)
(('c', 99),)
(('b', 98),)
(('d', 100),)
[('a', 97), ('c', 99), ('b', 98), ('d', 100)]
What key function would you like, to generate the value that is actually used
to define the ordering?
>>> sorted(dict((c,ord(c)) for c in 'abcd').items(), key=lambda t:t[0])
[('a', 97), ('b', 98), ('c', 99), ('d', 100)]
>>> sorted(dict((c,ord(c)) for c in 'abcd').items(), key=lambda t:t[1])
[('a', 97), ('b', 98), ('c', 99), ('d', 100)]
>>> sorted(dict((c,ord(c)) for c in 'abcd').items(), key=lambda t:-t[1])
[('d', 100), ('c', 99), ('b', 98), ('a', 97)]
>>> sorted(dict((c,ord(c)) for c in 'abcd').items(), key=lambda t:t[1]&1)
[('b', 98), ('d', 100), ('a', 97), ('c', 99)]
>>> sorted(dict((c,ord(c)) for c in 'abcd').items(), key=lambda
>>> t:(t[1]&1,t[1]))
[('b', 98), ('d', 100), ('a', 97), ('c', 99)]
>>> sorted(dict((c,ord(c)) for c in 'abcd').items(), key=lambda
>>> t:(t[1]&1,-t[1]))
[('d', 100), ('b', 98), ('c', 99), ('a', 97)]
And being able to reverse the end result is handy
>>> sorted(dict((c,ord(c)) for c in 'abcd').items(), key=lambda
>>> t:(t[1]&1,-t[1]), reverse=True)
[('a', 97), ('c', 99), ('b', 98), ('d', 100)]
You may need to upgrade your Python though ;-)
Regards,
Bengt Richter
--
http://mail.python.org/mailman/listinfo/python-list
Re: Any royal road to Bezier curves...?
Warren Francis wrote: > I'm fairly new to Python (2-3 months) and I'm trying to figure out a simple > way to implement Bezier curves... So far I've tried the following: > > http://runten.tripod.com/NURBS/ > ...which won't work because the only compiled binaries are for Windows 2000, > python 2.1. I'm on Windows XP (for now), using Python 2.4. I downloaded > the source distribution, but the header files aren't included, so I'm not > sure how to compile it. > > It appears there's some bezier functionality in the python that comes > Blender... but I'm not savvy enough yet to try and extract whatever makes > beziers work there, to make it work in my general-purpose Python programs. > > Basically, I'd like to specify a curved path of an object through space. 3D > space would be wonderful, but I could jimmy-rig something if I could just > get 2D... There's some 2D code (which could be trivially adapted to 3D) in PIDDLE/Sping. In the latest Sping download, look in the file pid.py at the Canvas.curvePoints() method. http://piddle.sourceforge.net/ > Are bezier curves really what I want after all? I dunno. It depends on how much flexibility you need. -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
setattr for secondary attribute
I apologize for asking maybe a very trivial question. I have a new class object A with slots. One of the slots is, for example, object spam. Object spam, in turn, also has slots and one of them is attribute eggs. I need to assign a new value to eggs. In other words, I need to perform the following: A.spam.eggs=newValue The problem is that I have only a string s='spam.eggs' with which to work, so I cannot write an expression written above. I tried to use setattr: setattr(A, s, newValue) but this does not work. It says that object A does not have attribute spam.eggs How would you do it? TIA. -- http://mail.python.org/mailman/listinfo/python-list
Any royal road to Bezier curves...?
I'm fairly new to Python (2-3 months) and I'm trying to figure out a simple way to implement Bezier curves... So far I've tried the following: http://runten.tripod.com/NURBS/ ...which won't work because the only compiled binaries are for Windows 2000, python 2.1. I'm on Windows XP (for now), using Python 2.4. I downloaded the source distribution, but the header files aren't included, so I'm not sure how to compile it. It appears there's some bezier functionality in the python that comes Blender... but I'm not savvy enough yet to try and extract whatever makes beziers work there, to make it work in my general-purpose Python programs. Basically, I'd like to specify a curved path of an object through space. 3D space would be wonderful, but I could jimmy-rig something if I could just get 2D... Are bezier curves really what I want after all? Any thoughts would be much appreciated. I've got some ideas I want to test, but if I can't find a simple implementation of curves, I'm going to get so bogged down in trying to do that part, I'll never get to what I'm excited about. :-P Warren -- http://mail.python.org/mailman/listinfo/python-list
Re: about dictionary
On Sun, 20 Nov 2005 07:12:08 -0800, Shi Mu <[EMAIL PROTECTED]> wrote:
>d is a dictionary.
d
>{0: [[0, 1], [0, 2]], 1: [[0, 1], [1, 2], [1, 3]], 2: [[0, 2], [1, 2],
>[2, 3]], 3: [[1, 3], [2, 3]]}
>
>for the value under each key, if the possible connection is in the
>dictionary, for example, under key 0. 1 and 2 were found to have a
>pair in some other places so get [0,1,2]
>hence, how to design a dictionary,
>let dicTry=3D
>{0: [[0, 1,2], 2: [[0, 1, 2], [1, 2,3]], 2: [[0, 1,2], [1, 2,3], 3: [1,2,3]=
>}
>Thanks a lot!
Sounds like some graph application? Maybe you can find something useful
in a link from
http://wiki.python.org/moin/PythonGraphApi
(which I found by googling for "vertex graph site:python.org" (without the
quotes) ;-)
Regards,
Bengt Richter
--
http://mail.python.org/mailman/listinfo/python-list
Re: best cumulative sum
David (Alan) Isaac wrote: > What's the good way to produce a cumulative sum? > E.g., given the list x, > cumx = x[:] > for i in range(1,len(x)): > cumx[i] = cumx[i]+cumx[i-1] > > What's the better way? Is there something that this doesn't do, or something it does do that it shouldn't? You could do it this way: # untested def cumulative_sum(L): CL = [] csum = 0 for x in L: csum += x CL.append(csum) return CL Whether it is better or worse depends on what you consider better or worse. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: best cumulative sum
David Isaac wrote: > What's the good way to produce a cumulative sum? > E.g., given the list x, > cumx = x[:] > for i in range(1,len(x)): > cumx[i] = cumx[i]+cumx[i-1] > > What's the better way? Define better. More accurate? Less code? -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: Aproximative string matching
[EMAIL PROTECTED] wrote: > This algorithm is called soundex. Here is one implementation example. > > http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52213 > > here is another: > http://effbot.org/librarybook/soundex.htm Soundex is *one* particular algorithm for approximate string matching. It is optimised for matching Anglo-American names (like Smith/Smythe), and is considered to be quite old and obsolete for all but the most trivial applications -- or so I'm told. Soundex will not match arbitrary changes -- it will match both cat and cet, but it won't match cat and mat. A more sophisticated approximate string matching algorithm will use the Levenshtein distance. You can find a Useless implementation here: http://www.uselesspython.com/download.php?script_id=108 Given a function levenshtein(s1, s2) that returns the distance between two strings, you could use it for approximate matching like this: def approx_matching(strlist, target, dist=1): """Matches approximately strings in strlist to a target string. Returns a list of strings, where each string matched is no further than an edit distance of dist from the target. """ found = [] for s in strlist: if levenshtein(s, target) <= dist: found.append(s) return s -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
best cumulative sum
What's the good way to produce a cumulative sum? E.g., given the list x, cumx = x[:] for i in range(1,len(x)): cumx[i] = cumx[i]+cumx[i-1] What's the better way? Thanks, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: about list
[EMAIL PROTECTED] wrote: > Shi Mu wrote: > >>How to run a function to make [1,2,4] become [[1,2],1,4],[2,4]]? >>Thanks! > > > You want [[1,2],[1,4],[2,4]]? That is, all combinations of 2 items > from > the list? You might want to look at: > http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/190465 > > import * from xpermutations [x for x in UniqueCombinations ([1,2,4], 2)] > > [[1, 2], [1, 4], [2, 4]] > > That web page also gives urls to other recipies that do the same thing. Dang, that's better than my version. $ ./combinations.py 2 1 2 4 [['1', '2'], ['1', '4'], ['2', '4']] def combinations( universe, n=None ): """ Return all possible combinations of length "n," where the elements of each combination are taken from the list "universe." """ result = [] if n == None: n = len( universe ) if n > len( universe ): # No combination of elements can have cardinality # greater than universe, which is by definition the list # of all possible elements. pass elif n < 0: # No combination can have negative cardinaltiy. pass elif n == 0: # Only the empty combination has cardinality 0. result.append( [ ] ) else: # 0 < n <= len( universe ) for i in xrange( len( universe ) ): elem = universe[i] post = universe[i+1:] for c in combinations( post, n - 1 ): choice = [ elem ] choice.extend( c ) result.append( choice ) return result if __name__ == "__main__": import sys if len( sys.argv ) < 2: sys.stderr.write( "usage: %s [elements ...]\n" % sys.argv[0] ) sys.exit(1) n = int( sys.argv[1] ) print repr( combinations( sys.argv[2:], n ) ) -- http://mail.python.org/mailman/listinfo/python-list
Re: Type-checking unpickled objects
> I guess I'll > need a throwaway instance of the class to run type() on to get a usable > type object for comparison, but I'll work something out. Never mind - I can just pass the name of the class, as it should be. -- http://mail.python.org/mailman/listinfo/python-list
Re: Aproximative string matching
This algorithm is called soundex. Here is one implementation example. http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52213 here is another: http://effbot.org/librarybook/soundex.htm -- http://mail.python.org/mailman/listinfo/python-list
How to install python2.4.2 on IRIX6.5 ?
Hello, I am trying to install python2.4.2 on a SGI origin3200 machine running IRIX6.5. The native c compiler was used to compile python. "./configure --prefix=/my/path/to/install" runs ok, then, "smake OPT= " runs ok but "smake test" gets errors, here is the output: 247 tests OK. 2 tests failed: test_fpformat test_locale 41 tests skipped: test_aepack test_al test_applesingle test_bsddb test_bsddb185 test_bsddb3 test_bz2 test_cd test_cl test_codecmaps_cn test_codecmaps_hk test_codecmaps_jp test_codecmaps_kr test_codecmaps_tw test_curses test_dl test_gdbm test_gl test_gzip test_imgfile test_ioctl test_linuxaudiodev test_macfs test_macostools test_nis test_normalization test_ossaudiodev test_pep277 test_plistlib test_scriptpackages test_socket_ssl test_socketserver test_sunaudiodev test_tcl test_timeout test_urllib2net test_urllibnet test_winreg test_winsound test_zipimport test_zlib Ask someone to teach regrtest.py about which tests are expected to get skipped on irix6. *** Error code 1 smake: Error: 1 error I also tried regrtest.py according the above instruction, origin3200% ./Lib/test/regrtest.py -s test_fpformat test_fpformat test test_fpformat failed -- Traceback (most recent call last): File "/disk2/jfxiao/local/source/Python-2.4.2/Lib/test/test_fpformat.py", line 51, in test_reasonable_values self.checkFix(realVal, d) File "/disk2/jfxiao/local/source/Python-2.4.2/Lib/test/test_fpformat.py", line 28, in checkFix self.assertEquals(result, expected) AssertionError: '-0' != '0' 1 test failed: test_fpformat origin3200% ./Lib/test/regrtest.py -s test_locale test_frozen 1 test OK. - Can somebody tell me what's the problem ? Thanks! Regards, xiaojf -- http://mail.python.org/mailman/listinfo/python-list
global definition
I have a code here. I understand i can not draw lines without the
global definition of lastX and lastY. But still confused by its use.
when should we use global definition?
from Tkinter import *
root = Tk()
c = Canvas(root, bg='#0e2e0e', height=500, width=1000)
frame = c
lastX=""
lastY=""
def click(event):
global lastX, lastY
if lastX != "":
c.create_line(lastX,lastY,event.x,event.y,fill="white")
lastX = event.x
lastY = event.y
c.bind('<1>',click)
c.pack()
root.mainloop()
--
http://mail.python.org/mailman/listinfo/python-list
Re: Web-based client code execution
John J. Lee wrote: > Paul Watson <[EMAIL PROTECTED]> writes: > > >>What are the options? >> >>The user to hits a web page, downloads code (Python I hope), execute it, >>and be able to return the results. It needs to be able to go through >>standard HTTP so that it could be run from behind a corporate firewall >>without any other ports being opened. >> >>Am I stuck doing an ActiveX control? > > [...] > > If you just need to talk on port 80, just go ahead and do that (module > socket, module httplib, module urllib2, urllib.getproxies, etc), and > write a normal desktop application. > > > If it must run in a browser, here is some food for thought: > > > Compile Python to JavaScript -- very cool > > http://www.aminus.org/blogs/index.php/phunt/2005/10/06/subway_s_new_ajax_framework > > http://www.aminus.org/blogs/index.php/phunt/2005/10/09/psst_crackajax_is_in_svn > > > Plain old AJAX with Python on server side > > https://sourceforge.net/projects/json-py/ > > http://www.google.co.uk/search?q=ajax+python&btnG=Search (um, ignore the 1st > result) > > > Write Java applets in Python > > http://www.jython.org/ > > > Flash 'local storage' > > http://www.macromedia.com/support/documentation/en/flashplayer/help/help02.html > > Sort-of AJAX-for-Flash stuff > > http://www.cs.unc.edu/~parente/tech/tr04.shtml > http://www.simonf.com/flap/ > > Flash itself (boo;-) > > http://www.macromedia.com/ > > > XUL and PyXPCOM (Firefox only) > > http://www.xulplanet.com/ > > http://trac.nunatak.com.au/projects/nufox > > > Firefox future capabilities in this direction (probably most of this > is relevant) > > http://www.mozilla.org/roadmap/gecko-1.9-roadmap.html > > http://weblogs.mozillazine.org/roadmap/archives/2005_09.html > > > John I appreciate your long list of references. For this task, I think the first answer may have to be the one with which to go. A standard application that talks through port 80 and perhaps can use proxies. My desire to have the code distributed through a web page is just to ensure that the user is running the correct version and has not hacked it in any way. I suppose I can checksum the local client application and compare it with what is on the server. Then, make a way to update... ARGH! Even when future browsers embed Python interpreters, the security considerations may be such that no one will want to accept code which can do much locally anyway. Probably the right thing for the public Internet, Makes it harder to develop internal system management tools. -- http://mail.python.org/mailman/listinfo/python-list
Re: Web-based client code execution
Paul Watson wrote: > Kent Johnson wrote: >> Stephen Kellett wrote: >>> ActiveState do a version of Python that can run in a script tag like >>> JavaScript and VBScript. This requires Windows Scripting Host. They >>> also do a similar thing for Perl, not sure about TCL. >> >> See >> http://groups.google.com/group/comp.lang.python/msg/2d34acee66b40830 > > Please correct my misunderstanding if I am wrong, but I thought that > this runs server-side only and requires Microsoft IIS as the httpd > server. Is that correct? I haven't tried it but the referenced article seems to be about including Python in a web page to be run in-browser by IE. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Type-checking unpickled objects
isinstance! Now why didn't I know about that? Thanks you. I guess I'll need a throwaway instance of the class to run type() on to get a usable type object for comparison, but I'll work something out. As to the security considerations...this is a small enough program with a limited enough release that I'm not going to sweat it, although I will keep this in mind. -- http://mail.python.org/mailman/listinfo/python-list
Re: Web-based client code execution
David Wahler wrote: > Steve wrote: > >>AJAX works because browsers can execute javascript. I don't know of a >>browser that can execute python. Basically your stuck with java or >>javascript because everything else really isn't cross platform > > > Don't jump to conclusions... > http://dwahler.ky/python/ > > If you really, really want Python in a browser, it's certainly > possible. :) > > -- David This looks interesting, but looks even more fragile than CrackAJAX. http://www.aminus.org/blogs/index.php/phunt/2005/10/06/subway_s_new_ajax_framework All of this comes down to Javascript which will still not allow me to read local, client files. Right? -- http://mail.python.org/mailman/listinfo/python-list
Re: about list
Shi Mu wrote: > How to run a function to make [1,2,4] become [[1,2],1,4],[2,4]]? > Thanks! You want [[1,2],[1,4],[2,4]]? That is, all combinations of 2 items from the list? You might want to look at: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/190465 >>> import * from xpermutations >>> [x for x in UniqueCombinations ([1,2,4], 2)] [[1, 2], [1, 4], [2, 4]] That web page also gives urls to other recipies that do the same thing. -- http://mail.python.org/mailman/listinfo/python-list
Re: Underscores in Python numbers
On Sun, 20 Nov 2005 15:50:10 +0100, Eric Jacoboni <[EMAIL PROTECTED]> wrote: >Mike Meyer <[EMAIL PROTECTED]> writes: > >> I've seen at least one language (forget which one) that allowed such >> separators, but only for groups of three. So 123_456 would be valid, >> but 9_1 would be a syntax error. > >Ada allows underscores in numeric literals since 1983, without >enforcing any grouping. The Ruby language allows also this >notation. You may write 1_000_001 or 1000_001 or 10_00_001, etc. (the >same for real numbers...). > Actually, I guess I could be convinced, even though I posted a you-can-do-this-now decorator to bracket the op's desired function defs. >When you have the habit to represent literals like that, all other >big numeric literals or workarounds to create grouping seem cryptic. > >-- >Eric Jacoboni, ne il y a 1435938104 secondes My previous smiley re your sig in this thread context still applies ;-) Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
Re: Web-based client code execution
Kent Johnson wrote: > Stephen Kellett wrote: > >> In message <[EMAIL PROTECTED]>, >> Steve <[EMAIL PROTECTED]> writes >> >>> AJAX works because browsers can execute javascript. I don't know of a >>> browser that can execute python. Basically your stuck with java or >>> javascript because everything else really isn't cross platform. >> >> >> >> ActiveState do a version of Python that can run in a script tag like >> JavaScript and VBScript. This requires Windows Scripting Host. They >> also do a similar thing for Perl, not sure about TCL. > > > See > http://groups.google.com/group/comp.lang.python/msg/2d34acee66b40830 > > Kent Please correct my misunderstanding if I am wrong, but I thought that this runs server-side only and requires Microsoft IIS as the httpd server. Is that correct? -- http://mail.python.org/mailman/listinfo/python-list
Re: Underscores in Python numbers
On Sun, 20 Nov 2005 15:50:10 +0100, Eric Jacoboni <[EMAIL PROTECTED]> wrote: >Mike Meyer <[EMAIL PROTECTED]> writes: > >> I've seen at least one language (forget which one) that allowed such >> separators, but only for groups of three. So 123_456 would be valid, >> but 9_1 would be a syntax error. > >Ada allows underscores in numeric literals since 1983, without >enforcing any grouping. The Ruby language allows also this >notation. You may write 1_000_001 or 1000_001 or 10_00_001, etc. (the >same for real numbers...). > >When you have the habit to represent literals like that, all other >big numeric literals or workarounds to create grouping seem cryptic. > >-- >Eric Jacoboni, ne il y a 1435938104 secondes Um, about your sig ... ;-) Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
Re: Underscores in Python numbers
On Sun, 20 Nov 2005 15:37:40 +, Steve Holden <[EMAIL PROTECTED]> wrote:
>David M. Cooke wrote:
>> Peter Hansen <[EMAIL PROTECTED]> writes:
>>
>>
>>>Steven D'Aprano wrote:
>>>
Dealing with numeric literals with lots of digits is
a real (if not earth-shattering) human interface problem: it is hard for
people to parse long numeric strings.
>>>
>>>I'm totally unconvinced that this _is_ a real problem, if we define
>>>"real" as being even enough to jiggle my mouse, let alone shattering the
>>>planet.
>>>
>>>What examples does anyone have of where it is necessary to define a
>>>large number of large numeric literals? Isn't it the case that other
>>>than the odd constants in various programs, defining a large number of
>>>such values would be better done by creating a data file and parsing
>>>it?
>>
>>
>> One example I can think of is a large number of float constants used
>> for some math routine. In that case they usually be a full 16 or 17
>> digits. It'd be handy in that case to split into smaller groups to
>> make it easier to match with tables where these constants may come
>> from. Ex:
>>
>> def sinxx(x):
>> "computes sin x/x for 0 <= x <= pi/2 to 2e-9"
>> a2 = -0.1 4
>> a4 = 0.00833 33315
>> a6 = -0.00019 84090
>> a8 = 0.0 27526
>> a10= -0.0 00239
>> x2 = x**2
>> return 1. + x2*(a2 + x2*(a4 + x2*(a6 + x2*(a8 + x2*a10
>>
>> (or least that's what I like to write). Now, if I were going to higher
>> precision, I'd have more digits of course.
>>
>Right, this is clearly such a frequent use case it's worth changing the
>compiler for.
>
Agreed, let the OP hack a special-purpose solution for a special-case problem,
e.g.
(tested just enough to show the idea on this post ;-)
>>> def fundef(funsrc, preprocess=None):
... def doprep(f):
... protect_f = {}
... try:
... src = funsrc.lstrip().rstrip()+'\n' # remove leading/trailing
blank lines
... exec (preprocess and preprocess(src) or src) in protect_f
... return type(f)(protect_f[f.func_name].func_code,
... f.func_globals, f.func_name, f.func_defaults,
f.func_closure)
... except Exception, e:
... raise ValueError, 'Unable to translate %r ... due to\n%s'%(
... funsrc.lstrip().splitlines()[0][:30], '%s:
%s'%(e.__class__.__name__, e))
... return doprep
...
Now that decorator allows you to pre-process a function source
(e.g. according to what the OP might want for a preprocess argument):
>>> import re
>>> numgap = re.compile(r'(\d+) (?=\d)')
>>> def prep(s): return numgap.sub(r'\1', s)
...
Then use it on the OP's example [1]
>>> @fundef("""
... def sinxx(x):
... "computes sin x/x for 0 <= x <= pi/2 to 2e-9"
... a2 = -0.1 4
... a4 = 0.00833 33315
... a6 = -0.00019 84090
... a8 = 0.0 27526
... a10= -0.0 00239
... x2 = x**2
... return 1. + x2*(a2 + x2*(a4 + x2*(a6 + x2*(a8 + x2*a10
... """, preprocess=prep)
... def sinxx(x): pass # (defines signature and defaults in current scope)
...
[1] Note that no editing of previous source
is required except bracketing like
@fundef("""
... """, preprocess=prep)
That last line is required for the decorator, but also (I think, not tested)
defines
the signature and arg defaults in the current scope, as opposed to where exec
compiles
in the decorator.
>>> sinxx
>>> import math
>>> def mxx(x): return x and math.sin(x)/x or 1.0
...
>>> sinxx(0), mxx(0)
(1.0, 1.0)
>>> sinxx(.1), mxx(.1)
(0.99833416647076856, 0.99833416646828155)
>>> sinxx(.2), mxx(.2)
(0.99334665398326816, 0.99334665397530608)
>>>
Seems to work, approximately ;-)
>>> @fundef("""
... def poo()
... syntax problems
... """)
... def poo(): pass
...
Traceback (most recent call last):
File "", line 1, in ?
File "", line 10, in doprep
ValueError: Unable to translate 'def poo()' ... due to
SyntaxError: invalid syntax (line 1)
Some hope of somewhat useful exceptions too ;-)
Regards,
Bengt Richter
--
http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Peter Hansen wrote: > [EMAIL PROTECTED] wrote: > > Using the same logic, we don't need types other than string in a DBMS > > as we can always convert a string field into some other types when it > > is needed. > > You mean, like SQLite does? (http://www.sqlite.org/datatypes.html) > Yup, they are using similar logic. -- http://mail.python.org/mailman/listinfo/python-list
Aproximative string matching
I'm searching for a library which makes aproximative string matching, for example, searching in a dictionary the word "motorcycle", but returns similar strings like "motorcicle". Is there such a library? -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
[EMAIL PROTECTED] wrote: > Using the same logic, we don't need types other than string in a DBMS > as we can always convert a string field into some other types when it > is needed. You mean, like SQLite does? (http://www.sqlite.org/datatypes.html) -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: path module / class
Neil Hodgson wrote: >>> There is a cost to the change as there will be two libraries that >>> have to be known to understand code. ... >At that point I was thinking about os.path and path.py. Readers will > encounter code that uses both of these libraries. Okay, granted. I guess this is the same as in any other case of deprecation (e.g. some people still have to work with code that uses apply() or string module methods). > Peter Hansen: >> We've mandated use of path.py internally for all projects because >> we've noticed (especially with non-expert Python programmers... i.e. >> junior and intermediate types, and senior types new to Python) a >> decrease in errors. > >A list of fault reports in this area would be useful evidence. Unfortunately, in an agile group such reports tend not to exist, and in many cases the errors are caught by a partner even as they are created, or by someone refactoring the code a day later. I have only anecdotal evidence, I'm afraid, unless I start digging through past subversion revisions in several projects. -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Alex Martelli wrote:
> [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>...
> > there are at least two behaviour. What I need is a "preferred order".
> > Say if I have designed a web form(correspond to a database table), I
> > just want say 3 fields that goes before anything else in the
> > presentation. The rest I don't care as the DBA may create more fields
> > later which I don't want to then update my code yet again.
>
> preferred_fields = ['foo', 'bar', 'baz']
>
> def process_preferred_fields():
> global preferred_fields
> temp = {}
> for i, field in enumerate(preferred_fields):
> temp[field] = '%s%s' % (chr(0), chr(i))
> preferred_fields = temp
> process_preferred_fields()
> del process_preferred_fields
>
> def sort_key(akey, preferred_fields=preferred_fields):
> return preferred_fields.get(akey, akey)
> del preferred_fields
>
> ## ...build dictionary d...
>
> # now output d...:
> for k in sorted(d, key=sort_key):
> print k, d[k]
>
> Season to taste if you want non-preferred fields emitted other than
> alphabetically, or if you want to wrap this stuff into a class, etc.
> (Note: untested code, so typos &c are quite possible). This assumes
> that no 'real' key is a non-string, and no 'real' key starts with
> chr(0), but it's quite easy to tweak for slightly different specs (at
> worst by defining a custom type designed to always compare less than any
> real key, and wrapping the preferred_fields entry in instances of that
> custom type... having such instances compare with each other based on
> the index within preferred_fields of the key they're wrapping, etc etc).
>
Thanks. For me, I don't need such complex thing, it is just like :
d = somedict_from_db()
prefer=['f','a',b']
def my_order(d):
for x in prefer:
if x in d: yield x
s = frozenset(prefer)
for x in d:
if x not in s: yield x
--
http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Christoph Zwerschke <[EMAIL PROTECTED]> writes: > Ben Finney wrote: >> Another possibility: ordered dictionaries are not needed when Python >> 2.4 has the 'sorted' builtin. > The 'sorted' function does not help in the case I have indicated, > where "I do not want the keys to be sorted alphabetically, but > according to some criteria which cannot be derived from the keys > themselves." And how would an ordered dictionary help in this case? http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Christoph Zwerschke <[EMAIL PROTECTED]> wrote: ... > The 'sorted' function does not help in the case I have indicated, where > "I do not want the keys to be sorted alphabetically, but according to > some criteria which cannot be derived from the keys themselves." Ah, but WHAT 'some criteria'? There's the rub! First insertion, last insertion, last insertion that wasn't subsequently deleted, last insertion that didn't change the corresponding value, or...??? Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Christoph Zwerschke <[EMAIL PROTECTED]> wrote: ... > I have started the thread in the first place because I believed it is > pretty unabmiguous what an "ordered dictionary" is and how it should I think you're wrong here. People in the past who have requested or implemented stuff they called 'ordered dicts' in the past had in mind drastically different things, based on some combination of insertion orders, keys, and _values_. So, ambiguity is definitely present in the phrase 'ordered dictionary', because there are so many different criteria whereby the 'ordering' could take place. Note the plural in 'insertion orderS': some people care about the FIRST time a key was added to a dict, some about the LAST time it was added, some about the latest time it was 'first inserted' (added and wasn't already there) as long as it's never been deleted since that occasion -- and these are just a few of the multifarious orders based on the time of insertions and deletions of keys. The number of variations is staggering, e.g., consider x['a'] = 1 x['b'] = 2 x['a'] = 1 in some applications you'd want to have 'b' come before 'a' because the last time of addition was earlier for 'b' -- but in others you might want 'a' first because the latest addition wasn't really one, since it didn't really change anything (because the value inserted was the same as the one already there -- it would be different, for those other apps, if the RHS of the third assignment was 0 rather than 1...). To get 'ordered dicts' into Python, you have to identify ONE unambiguous definition which has a large-enough number of use-cases, possibly customizable through some reasonably SIMPLE combination of flags and a callable or two, like the 'sorted' built-in has a 'reversed' flag and 'key' and 'cmp' optional callables. Expect a lot of flak from those who have been pining for an 'ordered dict' which does NOT match your one unambiguous definition...;-) If the field of use cases for 'ordered dicts' is just too fragmented, it's quite possible that it's best not to have any single kind built-in, even though, could all different use cases be combined (which by hypothesis is unfeasible), "critical mass" would be reached... Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
[EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
...
> there are at least two behaviour. What I need is a "preferred order".
> Say if I have designed a web form(correspond to a database table), I
> just want say 3 fields that goes before anything else in the
> presentation. The rest I don't care as the DBA may create more fields
> later which I don't want to then update my code yet again.
preferred_fields = ['foo', 'bar', 'baz']
def process_preferred_fields():
global preferred_fields
temp = {}
for i, field in enumerate(preferred_fields):
temp[field] = '%s%s' % (chr(0), chr(i))
preferred_fields = temp
process_preferred_fields()
del process_preferred_fields
def sort_key(akey, preferred_fields=preferred_fields):
return preferred_fields.get(akey, akey)
del preferred_fields
## ...build dictionary d...
# now output d...:
for k in sorted(d, key=sort_key):
print k, d[k]
Season to taste if you want non-preferred fields emitted other than
alphabetically, or if you want to wrap this stuff into a class, etc.
(Note: untested code, so typos &c are quite possible). This assumes
that no 'real' key is a non-string, and no 'real' key starts with
chr(0), but it's quite easy to tweak for slightly different specs (at
worst by defining a custom type designed to always compare less than any
real key, and wrapping the preferred_fields entry in instances of that
custom type... having such instances compare with each other based on
the index within preferred_fields of the key they're wrapping, etc etc).
Alex
--
http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
[EMAIL PROTECTED] wrote: > Personally, I have needs for ordered dict but I don't think it should > be in standard library though, as different situation called for > different behaviour for "ordered" and skewing my code to a standard lib > way is no good. I have started the thread in the first place because I believed it is pretty unabmiguous what an "ordered dictionary" is and how it should behave. That's why I asked myself why something that straigthforward has not been added to the standard lib yet. Maybe I'm wrong; I must admit that I haven't meditated about it very much. Do you have an example for different options of behavior? -- Christoph -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Christoph Zwerschke wrote: > [EMAIL PROTECTED] wrote: > > Personally, I have needs for ordered dict but I don't think it should > > be in standard library though, as different situation called for > > different behaviour for "ordered" and skewing my code to a standard lib > > way is no good. > > I have started the thread in the first place because I believed it is > pretty unabmiguous what an "ordered dictionary" is and how it should > behave. That's why I asked myself why something that straigthforward has > not been added to the standard lib yet. Maybe I'm wrong; I must admit > that I haven't meditated about it very much. > > Do you have an example for different options of behavior? > As mentioned, most ordered dict I saw is "insertion order" based. I assume that is the need of their creators. But that is not my need, so there are at least two behaviour. What I need is a "preferred order". Say if I have designed a web form(correspond to a database table), I just want say 3 fields that goes before anything else in the presentation. The rest I don't care as the DBA may create more fields later which I don't want to then update my code yet again. -- http://mail.python.org/mailman/listinfo/python-list
Re: about list
Shi Mu wrote: > How to run a function to make [1,2,4] become [[1,2],1,4],[2,4]]? > Thanks! From what I gather try: a = [1,2,4] n = list() for i in a: index = a.index(i) + 1 for x in a[index:]: n.append([i, x]) print n more elegant ways to do this, but its a start. hope this helps. Adonis -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Ben Finney wrote: > Without an example, it's hard to know what you want to do and whether > an ordered dictionary is the best way to do it. I have indicated an example, discussed in more detail in another subthread. >> There are already enough competing implementations. > Have they been sufficiently shaken out to show a clearly superior > version? Is any version sufficiently beneficial to write a PEP for its > inclusion in the standard library? At least it shows I'm not the only one who thinks ordered dictionaries may be sometimes nice to have. >> I simply wanted to ask why it is not available in the standard lib, >> since I simply don't know >> - has it not been demanded loud enough? > Loud demands don't count for much. PEPs with popular working > implementations do. Sorry, I did not mean "loud enough" but "often enough". The same what you are calling "popular." >> - because nobody presented a satisfying implementation yet? > I'm not sure what you mean by "satisfying". You can take your own definition: "sufficiently shaken out", "working", "popular", and "succifiently beneficial" and "proven (to the BDFL's criteria)". > Another possibility: ordered dictionaries are not needed when Python > 2.4 has the 'sorted' builtin. The 'sorted' function does not help in the case I have indicated, where "I do not want the keys to be sorted alphabetically, but according to some criteria which cannot be derived from the keys themselves." -- Christoph -- http://mail.python.org/mailman/listinfo/python-list
Re: about list
try to describe what you want as it is not very obvious, and has syntax error. Shi Mu wrote: > How to run a function to make [1,2,4] become [[1,2],1,4],[2,4]]? > Thanks! -- http://mail.python.org/mailman/listinfo/python-list
about list
How to run a function to make [1,2,4] become [[1,2],1,4],[2,4]]? Thanks! -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Ben Finney wrote: > Another possibility: ordered dictionaries are not needed when Python > 2.4 has the 'sorted' builtin. > What does sorted() have anythng to do with orders like insertion order, or some arbitary order that instead of a,b,c,d,e, I want it as e, c, b, d, a ? Personally, I have needs for ordered dict but I don't think it should be in standard library though, as different situation called for different behaviour for "ordered" and skewing my code to a standard lib way is no good. What I think is better is like the itertools recipe of giving example of how one can make their own based on the needs. -- http://mail.python.org/mailman/listinfo/python-list
Re: path module / class
Peter Hansen: >> There is a cost to the change as there will be two libraries that have >> to be known to understand code. > > Could you please clarify? Which two do you mean? At that point I was thinking about os.path and path.py. Readers will encounter code that uses both of these libraries. > We've mandated use of path.py internally for all projects because we've > noticed (especially with non-expert Python programmers... i.e. junior > and intermediate types, and senior types new to Python) a decrease in > errors. A list of fault reports in this area would be useful evidence. The relative occurence of particular failures (such as incorrect path joining) is difficult to estimate which leads to the common messy handwaving over API choices. To me, one of the bigger benefits of path.py is that it automatically uses Unicode strings on Windows NT+ which will behave correctly in more cases than byte strings. Neil -- http://mail.python.org/mailman/listinfo/python-list
Re: ownership problem?
Fredrik Lundh wrote: > Jeffrey Schwab wrote: > > >>>Is it correct to say that the typical ownership problem, which >>>frequently arises in C++, does not occur normally in Python? >> >>What "typical ownership problem" do you feel frequently arises in C++? >>If you are referring to the sometimes difficult task of determining >>which object owns a particular resource, why would it occur less in >>Python than in C++? > > > the problem isn't determining who owns it, the problem is determining > who's supposed to release it. that's not a very common problem in a > garbage-collected language... Yes it is. Memory is only one type of resource. There are still files and sockets to close, pipes to flush, log messages to be printed, GDI contexts to free, locks to release, etc. In C++, these things are generally done by destructors, which are called automatically and deterministically. I am not a Python Guru, but in Perl, Java, and other languages that have built-in garbage collectors, these tasks have to be done explicitly. I find that this forces a procedural approach, even in an otherwise object-oriented program. If you want something like automatic garbage collection in C++, I recommend the use of Factories with destructors that release the Factories' products. The zeitgeist in c.l.c++.moderated seems to prefer the use of smart (reference-counted) pointers, which also rely on destructors to release resources automatically. Plentry of free, open-source implementations are available. -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Fredrik Lundh wrote:
> if you restructure the list somewhat
> d = (
> ('pid', ('Employee ID', 'int')),
> ('name', ('Employee name', 'varchar')),
> ('sal', ('Salary', 'float'))
> )
> you can still loop over the list
> ...
> but you can easily generate an index when you need it:
> index = dict(d)
That's exactly the kind of things I find myself doing too often and what
I was talking about: You are using *two* pretty redundant data
structures, a dictionary and a list/tuple to describe the same thing.
Ok, you can use a trick to automatically create the dictionary from the
tuple, but still it feels somewhat "unnatural" for me. A "ordered
dictionary" would be the more "natural" data structure here.
I also wanted to mention the uglyness in the definition (nested tuples),
but then I understood that even an ordered dictionary would not
eliminate that uglyness, since the curly braces are part of the Python
syntax and cannot be used for creating ordered dictionaries anyway. I
would have to define the ordered dictionary in the very same ugly way:
d = odict(('pid', ('Employee ID', 'int')),
('name', ('Employee name', 'varchar')),
('sal', ('Salary', 'float')))
(Unless the Python syntax would be extend to use double curly braces or
something for ordered dictionaries - but I understand that this is not
an option.)
-- Christoph
--
http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Fredrik Lundh wrote: > but you can easily generate an index when you need it: > > index = dict(d) > > name, type = index["pid"] > print name > > the index should take less than a microsecond to create, and since it > points to the members of the original dict, it doesn't use much memory > either... > Using the same logic, we don't need types other than string in a DBMS as we can always convert a string field into some other types when it is needed. Of course there are more than one way to skin a cat(well it may be against the general idiom of python) but in some situation certain way is preferred. -- http://mail.python.org/mailman/listinfo/python-list
Re: what happens when the file begin read is too big for all lines tobe?read with "readlines()"
"Ross Reyes" <[EMAIL PROTECTED]> writes: > Yes, I have read this part > How does one tell exactly what the limitation is to the size of the > returned list of strings? There's not really a good platform-indendent way to do that, because you'll get memory until the OS won't give you any more. http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. -- http://mail.python.org/mailman/listinfo/python-list
Re: examining python objects
[EMAIL PROTECTED] wrote: > Bruno Desthuilliers wrote: > >>[EMAIL PROTECTED] a écrit : >> >>>Is there a function/class/module/whatever I can use to >>>look at objects? I want something that will print the object's >>>value (if any) in pretty-printed form, and list all it's attributes >>>and their values. And do all that recursively. >>>I want to be able to find out everything about an object that >>>Python can introspectively find out. >> >>Then check the inspect module > > > I want a callable, ready-to-use class or function. > Inspect provides soime funtions that would be useful for wrinting > such a class or function, but does not provide one. > > I seems that nobody who has written or used such a tool reads > this group, or feels like responding. > > FWIW, (for anyone looking for something similar in the future) > I found http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/137951 > which will format and print an object's attributes. By combining that > and pprint in the Python distrib, I think can coble up what I am > looking > for. > > Still, it is discouraging that such a basic thing is not provided with > python, or at lleast easily available in some library. > In the interactive mode, you might try >> help(object) Colin W. -- http://mail.python.org/mailman/listinfo/python-list
Re: Underscores in Python numbers
Peter Hansen wrote: > [EMAIL PROTECTED] wrote: > > Peter Hansen wrote: > > > >>But why would anyone want to create numeric literals for credit card > >>numbers? > >> > > May be for space saving ? But storage space being so cheap, this is not > > a very good reason, but still a reason. > > Space saving where? Why would you have any credit card numbers stored > in any application? Even a credit card company isn't going to write > code that has the numbers stored as *literals*! I am not the one asking for it, only guessing the reason and credit card company does save it in the database. So saving as half byte numeric(or 64 bit integer) does save a bit of space comparing with string. > > There's only one place I can think of right now where you might want > that: in automated tests for code that processes credit card numbers. > And you definitely do not need to "save space" in that situation... > That usually don't need it as one big number but usually more easier to code if treating as string(like checksum), something like: for digits in cc: checksum += int(digits) -- http://mail.python.org/mailman/listinfo/python-list
Re: HTML generation vs PSP vs Templating Engines
>> Using templates means that the code can work with different templates, >> and this should be seamless, it also means that different code can be >> used with the templates, for example if different languages are used. > This seems to contradict your statement that you dislike 'embedding > code or html in each other', since the scenarios you describe still > involve embedding presentation logic in markup. (The only templating > systems that *completely* separate logic from markup are the DOM-style > ones.) Perhaps that is why I implemented my own mechanisms for templating. My templates contain no logic at all and can be used from my Python programs, Cobol or C equally well. Contrarywise, my Python programs choose at runtime the required template (depending on configuration, user request or other) and then the same program code will output HTML, XML, EDIFACT, CSV, printed report or other dependant entirely on the content of the template file. -- http://mail.python.org/mailman/listinfo/python-list
Re: How to draw a dash line in the Tkinter?
On 11/20/05, Fredrik Lundh <[EMAIL PROTECTED]> wrote: > Ben Bush wrote: > > > How to draw a dash line in the Tkinter? > > use the dash option. e.g. > >canvas.create_line(xy, fill="red", dash=(2, 4)) >canvas.create_line(xy, fill="red", dash=(6, 5, 2, 4)) > > (the tuple contains a number of line lengths; lengths at odd positions > are drawn, lengths at even positions are gaps. note that not all com- > binations are supported on all platforms; if Tkinter cannot find an exact > match, it will pick a the "closest possible"). > > where can I find the option settings for dash line? -- http://mail.python.org/mailman/listinfo/python-list
Re: combine doxygen and doc-strings?
Gabriel Zachmann wrote: > Is there a way to combine doxygen comments, like this one If you are not tied to doxygen, you might consider epydoc - it uses the docstrings, and restructured text which is friendly to the eye. Regards, Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: [Tutor] need a tutorial in tokens ,different types
> could any one suggest me tutorials in different tokenizations and > clear describtion of how can i use token type and assign diff attributes > to tokens What kind of tokens? Are we talking l;exical tokens in a parser or security tokens or what? > also good tutorials in diff data types in python The official documentaton explains most of it. You can try the Raw Materials topic in my tutorial if you like. Alan G Author of the learn to program web tutor http://www.freenetpages.co.uk/hp/alan.gauld -- http://mail.python.org/mailman/listinfo/python-list
Re: Underscores in Python numbers
Raymond Hettinger a écrit : > Gustav Hållberg wrote: > >>I tried finding a discussion around adding the possibility to have >>optional underscores inside numbers in Python. This is a popular option >>available in several "competing" scripting langauges, that I would love >>to see in Python. >> >>Examples: >> 1_234_567 >> 0xdead_beef >> 3.141_592 > > > I suppose it could be done. OTOH, one could argue that most production > code has no business hardwiring-in numerical constants greater than 999 > ;-) > That's what I thought at first, but Steven D'Aprano made some good points here IMHO, ie : """ Not all numeric constants used have simple formulae, or *any* formulae, or can be calculated on the fly in any reasonable time. Numeric programming often uses magic constants which truly are "magic" (in the sense that where they come from requires deep, difficult, and sometimes hidden knowledge). Nobody sensible wants to be typing in long strings of digits, but sometimes it is unavoidable. """ and """ Another sensible usage case is in the interactive interpreter. If you are using Python interactively, you may wish to use numeric literals with large numbers of digits. It is not feasible to read them from a data file, and using a special converter function is impractical and unnecessary. """ So even if it's far from a common use case for *most* Python users, it may be a common use case for *some* Python users. Also, someone mentionned the use of Python as a configuration langage - which is probably a much more common use case. So FWIW, I'd be +1 on adding it *if and only if*: - it's trivial to implement [1] - it doesn't break older code and +1 on the space as group delimiter BTW. [1]: I never wrote a language by myself, but I've played a bit with parsers and lexers, and I _guess_ (which implies I may be wrong !-) it wouldn't require much work to add support for a "literal numeric grouping" syntax in Python. -- http://mail.python.org/mailman/listinfo/python-list
Re: ownership problem?
Jeffrey Schwab wrote: > > Is it correct to say that the typical ownership problem, which > > frequently arises in C++, does not occur normally in Python? > > What "typical ownership problem" do you feel frequently arises in C++? > If you are referring to the sometimes difficult task of determining > which object owns a particular resource, why would it occur less in > Python than in C++? the problem isn't determining who owns it, the problem is determining who's supposed to release it. that's not a very common problem in a garbage-collected language... -- http://mail.python.org/mailman/listinfo/python-list
Re: Ajax for the Developers
"Sabin.A.K, Bangalore" <[EMAIL PROTECTED]> writes: [...] > 1. Changing state with links (GET requests) > 2.Asynchronously performing batch operations I don't understand those two. > 3.Breaking the back button [...] http://en.wikipedia.org/wiki/AJAX Also of interest: http://www.mozillazine.org/talkback.html?article=7162 John -- http://mail.python.org/mailman/listinfo/python-list
Re: Underscores in Python numbers
On Sun, 20 Nov 2005 15:52:29 -0500, Roy Smith wrote: > You have described, if memory serves, a Taylor series, and those > coefficients are 1/3!, 1/5!, 1/7!, etc. What I would do, rather than > embedding the numeric constants in the code, is embed the formula and have > the machine compute the actual values at import time. At the very least, > have them machine generated and saved. You certainly don't want to be > typing in long strings of digits like that. Not all numeric constants used have simple formulae, or *any* formulae, or can be calculated on the fly in any reasonable time. Numeric programming often uses magic constants which truly are "magic" (in the sense that where they come from requires deep, difficult, and sometimes hidden knowledge). Nobody sensible wants to be typing in long strings of digits, but sometimes it is unavoidable. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: Underscores in Python numbers
On Sun, 20 Nov 2005 09:27:28 -0500, Peter Hansen wrote: > But why would anyone want to create numeric literals for credit card > numbers? Credit card numbers is not a sensible usage case. Neither are books' ISBNs, or tax file numbers, or telephone numbers -- these are all instances where it makes sense to read them from a data file and use a converter function. One sensible usage case is numeric calculations, where you often are using numeric constants in some formula, and those constants may have ten, twelve, fifteen digits. Being able to group digits makes it considerable easier to enter the numbers, as well as proof-read your code. c = 25.173 268 901 910 023 is considerably easier for the human reader to parse than: c = 25.173268901910023 Calculating the number in place is not an acceptable solution: c = 25.173 + 268e-3 + 901e-6 + 910e-9 + 23e-12 is bad for a number of reasons: - it implies c is a calculated sum when it is not; - it harms comprehension; - it may very well lose accuracy; - it is easy to miscalculate and end up with a completely wrong number; - it complicates and obfuscates the compiled code. Another sensible usage case is in the interactive interpreter. If you are using Python interactively, you may wish to use numeric literals with large numbers of digits. It is not feasible to read them from a data file, and using a special converter function is impractical and unnecessary. I don't know whether these two usage cases will be enough to justify changing the way Python handles numeric literals -- Guido seems quite conservative in what he adds to the language, so unless there is either great demand or it scratches a particular itch he has personally, I doubt it will fly. But we'll never know unless we try, hey? *wink* -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: Delays getting data on sys.stdin.readline() ?
Christian Convey wrote: > So here's what I don't get: If "producer" was retaining its output for > a while for the sake of efficiency, I would expect to see that effect > when I just run "producer" on the command line. That is, I would > expect the console to not show any output from "producer" until > "producer" terminates. But instead, I see the output immediately. So > why, when I pipe the output to "consumer", doesn't "consumer" get > access to that data as its produced unless "consumer" is explicitely > calling sys.stdout.flush(). > > Any thoughts? your terminal is not a pipe. $ man stdout ... CONSIDERATIONS The stream stderr is unbuffered. The stream stdout is line-buffered when it points to a terminal. Partial lines will not appear until fflush(3) or exit(3) is called, or a newline is printed. This can produce unexpected results, especially with debugging output. The buffering mode of the standard streams (or any other stream) can be changed using the setbuf(3) or setvbuf(3) call. Note that in case stdin is associated with a termi nal, there may also be input buffering in the terminal driver, entirely unrelated to stdio buffering. (Indeed, normally terminal input is line buffered in the kernel.) This kernel input handling can be modified using calls like tcsetattr(3); see also stty(1), and termios(3). ... -- http://mail.python.org/mailman/listinfo/python-list
Re: ownership problem?
Gabriel Zachmann wrote: > Is it correct to say that the typical ownership problem, which > frequently arises in C++, does not occur normally in Python? What "typical ownership problem" do you feel frequently arises in C++? If you are referring to the sometimes difficult task of determining which object owns a particular resource, why would it occur less in Python than in C++? -- http://mail.python.org/mailman/listinfo/python-list
Re: ownership problem?
Gabriel Zachmann <[EMAIL PROTECTED]> wrote: > Is it correct to say that the typical ownership problem, which > frequently arises in C++, does not occur normally in Python? Could you explain what you mean by "the typical ownership problem"? -- \ "Jealousy: The theory that some other fellow has just as little | `\ taste." -- Henry L. Mencken | _o__) | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
Re: Is Python weak on the web side?
Too many options. Google: python web frameworks The first couple of links will point you to enough resources. -- http://mail.python.org/mailman/listinfo/python-list
Re: Web-based client code execution
Paul Watson <[EMAIL PROTECTED]> writes: > What are the options? > > The user to hits a web page, downloads code (Python I hope), execute it, > and be able to return the results. It needs to be able to go through > standard HTTP so that it could be run from behind a corporate firewall > without any other ports being opened. > > Am I stuck doing an ActiveX control? [...] If you just need to talk on port 80, just go ahead and do that (module socket, module httplib, module urllib2, urllib.getproxies, etc), and write a normal desktop application. If it must run in a browser, here is some food for thought: Compile Python to JavaScript -- very cool http://www.aminus.org/blogs/index.php/phunt/2005/10/06/subway_s_new_ajax_framework http://www.aminus.org/blogs/index.php/phunt/2005/10/09/psst_crackajax_is_in_svn Plain old AJAX with Python on server side https://sourceforge.net/projects/json-py/ http://www.google.co.uk/search?q=ajax+python&btnG=Search (um, ignore the 1st result) Write Java applets in Python http://www.jython.org/ Flash 'local storage' http://www.macromedia.com/support/documentation/en/flashplayer/help/help02.html Sort-of AJAX-for-Flash stuff http://www.cs.unc.edu/~parente/tech/tr04.shtml http://www.simonf.com/flap/ Flash itself (boo;-) http://www.macromedia.com/ XUL and PyXPCOM (Firefox only) http://www.xulplanet.com/ http://trac.nunatak.com.au/projects/nufox Firefox future capabilities in this direction (probably most of this is relevant) http://www.mozilla.org/roadmap/gecko-1.9-roadmap.html http://weblogs.mozillazine.org/roadmap/archives/2005_09.html John -- http://mail.python.org/mailman/listinfo/python-list
Re: ownership problem?
Gabriel Zachmann a écrit : > Is it correct to say that the typical ownership problem, which > frequently arises in C++, does not occur normally in Python? What is this "typical ownership problem" ? -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
Christoph Zwerschke wrote:
> The example above is a bit misleading, because using 'a', 'b' as keys
> can give the impression that you just have to sort() the keys to have
> what you want. So let's make it more realistic:
>
> d = { 'pid': ('Employee ID', 'int'),
>'name': ('Employee name', 'varchar'),
>'sal': ('Salary', 'float') }
>
> Now if I want these things to be presented in this order, I need to run
> through a separate list ('pid', 'name', 'sal') that holds the order.
>
> Ok, you could simply use a list instead of a dictionary:
>
> d = ( ('pid', 'Employee ID', 'int'),
>('name', 'Employee name', 'varchar'),
>('sal', 'Salary', 'float') )
if you restructure the list somewhat
d = (
('pid', ('Employee ID', 'int')),
('name', ('Employee name', 'varchar')),
('sal', ('Salary', 'float'))
)
you can still loop over the list
for key, (name, type) in d:
print key, name, type # e.g. generate form entry
> This works as long as you *only* have to go through the list
> sequentially. But maybe you want to print the name with its description
> at some other place as well. Now how do you access its description
> 'Employee name' so easily?
but you can easily generate an index when you need it:
index = dict(d)
name, type = index["pid"]
print name
the index should take less than a microsecond to create, and since it
points to the members of the original dict, it doesn't use much memory
either...
--
http://mail.python.org/mailman/listinfo/python-list
Re: Is Python weak on the web side?
On 19/11/05, Michael Goettsche <[EMAIL PROTECTED]> wrote: > On Sunday 20 November 2005 00:24, Tony wrote: > > If I'd like to learn Python for web-development, what are the options > > available? > > A nice framework is CherryPy: http://www.cherrypy.org > or Turbogears, which is based on CherryPy: http://www.turbogears.org/ See also Django for CMS type sites. -- Cheers, Simon B, [EMAIL PROTECTED], http://www.brunningonline.net/simon/blog/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Is Python weak on the web side?
Tony a écrit : > If I'd like to learn Python for web-development, what are the options > available? There are too many *good* options for web developpement in Python. > Thanks. tony -- http://mail.python.org/mailman/listinfo/python-list
ownership problem?
Is it correct to say that the typical ownership problem, which frequently arises in C++, does not occur normally in Python? Best regards, Gabriel. -- /---\ | Any intelligent fool can make things bigger, more complex,| | or more violent. It takes a touch of genius - and a lot of courage - | | to move in the opposite direction. (Einstein) | \---/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Web-based client code execution
David Wahler wrote: > Steve wrote: > >>AJAX works because browsers can execute javascript. I don't know of a >>browser that can execute python. Basically your stuck with java or >>javascript because everything else really isn't cross platform > > > Don't jump to conclusions... > http://dwahler.ky/python/ > > If you really, really want Python in a browser, it's certainly > possible. :) > > -- David > well in firefox 1.07 I seem to be getting Error: unmarshal is not defined Source File: http://dwahler.ky/python/ Line: 133 -- Robin Becker -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
[restored my attribution line so we know who said what] Christoph Zwerschke <[EMAIL PROTECTED]> wrote: > Ben Finney wrote: > > In what cases do you find yourself needing a dict that preserves > > its key order? Can you present a use case that would be improved > > by an ordered dict? > > There are too many different situations and it would be too much to > explain them here, usually in the case mentioned above where the > keys are not sorted alphabetically. Without an example, it's hard to know what you want to do and whether an ordered dictionary is the best way to do it. > > For my part, I consider it a virtue of Python that the standard > > library doesn't change rapidly. It allows many competing > > implementations to be shaken out before everyone starts depending > > on any one of them. > > Ok, but this can be used as an argument to not add anything to the > standard lib any more. I hope not. Rather, it's an argument not to add something to the standard library until it's proven (to the BDFL's criteria) that it's better in than out. > There are already enough competing > implementations. Have they been sufficiently shaken out to show a clearly superior version? Is any version sufficiently beneficial to write a PEP for its inclusion in the standard library? > I simply wanted to ask why it is not available in the standard lib, > since I simply don't know > > - has it not been demanded loud enough? Loud demands don't count for much. PEPs with popular working implementations do. > - is it really not needed (if you need it it shows you are doing > something wrong)? You dismissed a request for your use cases with handwaving. How can we know? > - because nobody presented a satisfying implementation yet? I'm not sure what you mean by "satisfying". > - are there hidden difficulties or controversial issues? Another possibility: ordered dictionaries are not needed when Python 2.4 has the 'sorted' builtin. -- \ "Those who will not reason, are bigots, those who cannot, are | `\ fools, and those who dare not, are slaves." -- "Lord" George | _o__)Gordon Noel Byron | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
Re: func(*params)
David Duerrenmatt wrote: > For some reasons, I've to use Python 1.5.2 and am looking for a workaround: > > In newer Python versions, I can call a function this way: > > func = some_function > func(*params) > > Then, the list/tuple named params will automatically be "expanded" and > n=len(params) arguments will be submitted. > > Python 1.5.2 doesn't support this kind of function call. use apply(func, params) or result = apply(func, params) more info: >>> help(apply) Help on built-in function apply in module __builtin__: apply(...) apply(object[, args[, kwargs]]) -> value Call a callable object with positional arguments taken from the tuple args, and keyword arguments taken from the optional dictionary kwargs. Note that classes are callable, as are instances with a __call__() method. Deprecated since release 2.3. Instead, use the extended call syntax: function(*args, **keywords). -- http://mail.python.org/mailman/listinfo/python-list
Re: Command line
"amfr" wrote: > Hoe would I call something on the command line from python, e.g. "ls > -la"? os.system(cmd), or some relative: http://docs.python.org/lib/os-process.html http://docs.python.org/lib/os-newstreams.html#os-newstreams or http://docs.python.org/lib/module-subprocess.html ::: also note that you shouldn't use external commands for trivial things like getting a list of files or getting the size of a file; you can get a list of all files in a directory with files = os.listdir(directory) for file in files: file = os.path.join(directory, file) # full path ... or files = glob.glob(pattern) for file in files: ... and you can get information about a given file with st = os.stat(file) size = st.st_size mtime = st.st_mtime (etc) or size = os.path.getsize(file) mtime = os.path.getmtime(file) (etc) -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
[EMAIL PROTECTED] schrieb:
> By ordered dict, one usually wants order that is arbitary which cannot
> be derived from the content, say insertion order(most ordered dict I
> saw use this order).
> I am writing a web applications(simple forms) which has a number of
> fields. Each field naturally has a name and a number of
> attributes(formatting etc.), like this :
> d = {'a':{...}, 'b':{}}
Things like that are also my typical use case. The keys usually contain
things like database fields or html form fields, the values contain the
corresponding description, formatting, data type or data itself etc.
The example above is a bit misleading, because using 'a', 'b' as keys
can give the impression that you just have to sort() the keys to have
what you want. So let's make it more realistic:
d = { 'pid': ('Employee ID', 'int'),
'name': ('Employee name', 'varchar'),
'sal': ('Salary', 'float') }
Now if I want these things to be presented in this order, I need to run
through a separate list ('pid', 'name', 'sal') that holds the order.
Ok, you could simply use a list instead of a dictionary:
d = ( ('pid', 'Employee ID', 'int'),
('name', 'Employee name', 'varchar'),
('sal', 'Salary', 'float') )
This works as long as you *only* have to go through the list
sequentially. But maybe you want to print the name with its description
at some other place as well. Now how do you access its description
'Employee name' so easily?
-- Christoph
--
http://mail.python.org/mailman/listinfo/python-list
BaseHTTPServer module
>From the BaseHTTPServer module, how do i gget the POST or GET data sent by the client? Is it stired the the file they requested? e.g. objectname.path -- http://mail.python.org/mailman/listinfo/python-list
BaseHTTPServer module
>From the BaseHTTPServer module, how do i gget the POST or GET data sent by the client? Is it stired the the file they requested? e.g. objectname.path -- http://mail.python.org/mailman/listinfo/python-list
Re: Web-based client code execution
Paul Watson wrote: > I have read some about AJAX. Is there an APAX coming for Python? Not until browsers have embedded Python interpreters. There's been talk about doing this in Mozilla, but I don't think the talk has turned into usable code, yet. -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: Why are there no ordered dictionaries?
> What answers have you received that have not been satisfactory? I googled a little bit and haven't found many answers at all. Some were in the posting I mentioned: Stuff should go into the standard lib only when it is mature and "right" enough. However, we are already at Python 2.4 and there is still no ordered dictionary, though there is a lot of other specialized stuff. > Some possible answers: The native dict is very fast, partly because > the implementation doesn't need to ensure any particular ordering. Ok, but that's not an argument against providing ordered dictionaries as well. > Ordering the keys isn't the normal case, and can be done easily when > needed. That depends. Maybe I do not want the keys to be sorted alphabetically, but according to some criteria which cannot be derived from the keys themselves. > You asked "why not" rather than "has anyone done this anyway"; if > you asked the latter of the Python Cookbook, you might find something > like this. Yes, I also found that others have done it more than once, and I know that it's not so difficult to do. There are at least two recipes in the mentioned cookbook and there is odict in pythonutils. The question was why is it not available in the *standard* lib. > In what cases do you find yourself needing a dict that preserves its > key order? Can you present a use case that would be improved by an > ordered dict? There are too many different situations and it would be too much to explain them here, usually in the case mentioned above where the keys are not sorted alphabetically. I often solve them by using two data structures, a list or tuple, plus a dictionary. For instance, the list could contain the names of database fields which shall be output in a certain order, and the dictionary values could contain human readable description of the database fields for headers or something. Instead of maintaining both data structures I feel it would be more natural to use only one ordered dictionary. > For my part, I consider it a virtue of Python that the standard > library doesn't change rapidly. It allows many competing > implementations to be shaken out before everyone starts depending on > any one of them. Ok, but this can be used as an argument to not add anything to the standard lib any more. There are already enough competing implementations. Also, the implementation details are not so important, there must be only agreement on the interface and behavior which should not be so difficult in this case. I simply wanted to ask why it is not available in the standard lib, since I simply don't know - has it not been demanded loud enough? - is it really not needed (if you need it it shows you are doing something wrong)? - because nobody presented a satisfying implementation yet? - are there hidden difficulties or controversial issues? -- Christoph -- http://mail.python.org/mailman/listinfo/python-list
Re: Delays getting data on sys.stdin.readline() ?
On 11/19/05, Mike Meyer <[EMAIL PROTECTED]> wrote: > Christian Convey <[EMAIL PROTECTED]> writes: > > I've got a program that (ideally) perpetually monitors sys.stdin for > > lines of text. As soon as a line comes in, my program takes some > > action. > > The problem is, it seems like a very large amount of data must > > accumulate on sys.stdin before even my first invocation of readline() > > returns. This delay prevents my program from being responsive in the > > way it must be. > > readline normally returns as soon as it sees a newline. External > conditions may cause this to change, or make it impossible. Without > knowing those external conditions, the best we can do is guess as to > what might be the problem. > > > Has anyone else seen this effect? If so, is there a reasonable workaround? > > Yes, and maybe. Depends on what's causing the problem. Tell us more > about the program, and what sys.stdin is connected to, and the > platform you're running on, and someone should be able to provide > explicit information. OK, I've fixed it, but I don't understand why the fix works. Let's say I've got two Python programs, I'll call "producer" and "consumer". "producer" runs for a long time and occasionally while running sends lines of text to stdout. "consumer" is typically blocked in a call to sys.stdin.readline(). When I run "producer" on its own, I see its output appear on the console pretty much immediately after calling the "print" command. But when I pipe "producer"s output to "consumer"s stdin on the Linux command line, "consumer" stays blocked on its first call to sys.stdin.readline() until the "producer" program terminates. At that point, "consumer" seems to immediately get access to all of the stdout produced by "producer". I've found I can fix this problem by modifying "producer" so that immediately after each "print" command, I call sys.stdout.flush(). When I make this modification, I find that "consumer" has access to the output of "producer" immediately after "producer" issues a "print" statement. So here's what I don't get: If "producer" was retaining its output for a while for the sake of efficiency, I would expect to see that effect when I just run "producer" on the command line. That is, I would expect the console to not show any output from "producer" until "producer" terminates. But instead, I see the output immediately. So why, when I pipe the output to "consumer", doesn't "consumer" get access to that data as its produced unless "consumer" is explicitely calling sys.stdout.flush(). Any thoughts? Thanks, Christian -- http://mail.python.org/mailman/listinfo/python-list
Re: Speeding up multiple regex matches
"Talin" wrote: > I've run in to this problem a couple of times. Say I have a piece of > text that I want to test against a large number of regular expressions, > where a different action is taken based on which regex successfully > matched. The naive approach is to loop through each regex, and stop > when one succeeds. However, I am finding this to be too slow for my > application -- currently 30% of the run time is being taken up in the > regex matching. > > I thought of a couple of approaches, but I am not sure how to make them > work: > > 1) Combine all of the regular expressions into one massive regex, and > let the regex state machine do all the discriminating. The problem with > this is that it gives you no way to determine which regex was the > matching one. use a capturing group for each alternative, and use lastindex to quickly find the match: http://docs.python.org/lib/match-objects.html lastindex The integer index of the last matched capturing group, or None if no group was matched at all. also see: http://effbot.org/zone/xml-scanner.htm -- http://mail.python.org/mailman/listinfo/python-list
Re: Underscores in Python numbers
[EMAIL PROTECTED] (David M. Cooke) wrote: > One example I can think of is a large number of float constants used > for some math routine. In that case they usually be a full 16 or 17 > digits. It'd be handy in that case to split into smaller groups to > make it easier to match with tables where these constants may come > from. Ex: > > def sinxx(x): > "computes sin x/x for 0 <= x <= pi/2 to 2e-9" > a2 = -0.1 4 > a4 = 0.00833 33315 > a6 = -0.00019 84090 > a8 = 0.0 27526 > a10= -0.0 00239 > x2 = x**2 > return 1. + x2*(a2 + x2*(a4 + x2*(a6 + x2*(a8 + x2*a10 > > (or least that's what I like to write). Now, if I were going to higher > precision, I'd have more digits of course. You have described, if memory serves, a Taylor series, and those coefficients are 1/3!, 1/5!, 1/7!, etc. What I would do, rather than embedding the numeric constants in the code, is embed the formula and have the machine compute the actual values at import time. At the very least, have them machine generated and saved. You certainly don't want to be typing in long strings of digits like that. -- http://mail.python.org/mailman/listinfo/python-list
Re: Command line
amfr wrote: > Hoe would I call something on the command line from python, e.g. "ls > -la"? Use the module subprocess - otherwise maybe popen2 or os. Regards, Diez -- http://mail.python.org/mailman/listinfo/python-list
need a tutorial in tokens ,different types
hello all could any one suggest me tutorials in different tokenizations and clear describtion of how can i use token type and assign diff attributes to tokens ,also good tutorials in diff data types in python thanks every body enas Yahoo! FareChase - Search multiple travel sites in one click. -- http://mail.python.org/mailman/listinfo/python-list
Re: Command line
What OS are you using. I'm not sure about anything else but on a mac
it's:
>>import os
>>os.system("ls -la")
--
http://mail.python.org/mailman/listinfo/python-list
Command line
Hoe would I call something on the command line from python, e.g. "ls -la"? -- http://mail.python.org/mailman/listinfo/python-list
