Re: What's going on here?
On Monday, May 23, 2016 at 9:47:15 AM UTC+12, DFS wrote: > def splitrange(b,e,g): > sr=[] > for i in range(b,e,g): > bg=i;eg=min(e,bg+g-1) > sr.append((bg,eg)) > return sr To be more in keeping with the Python ethos, I would take out the “-1”. -- https://mail.python.org/mailman/listinfo/python-list
Re: function with list argument defaulting to [] - what's going on here???
On 14 Apr 2007 20:20:42 -0700, Paddy [EMAIL PROTECTED] wrote:
On Apr 15, 3:58 am, Steven D'Aprano
[EMAIL PROTECTED] wrote:
On Sat, 14 Apr 2007 17:33:11 -0800, Troy Melhase wrote:
On 4/14/07, Mike [EMAIL PROTECTED] wrote:
While trying to write a recursive function involving lists, I came
across some (to me) odd behavior which I don't quite understand. Here's
a trivial function showing the problem.
fromhttp://docs.python.org/ref/function.html:
Default parameter values are evaluated when the function definition is
executed. This means that the expression is evaluated once, when the
function is defined, and that that same ``pre-computed'' value is used
for each call. This is especially important to understand when a
default parameter is a mutable object, such as a list or a dictionary:
if the function modifies the object (e.g. by appending an item to a
list), the default value is in effect modified.
This comes up so often that I wonder whether Python should issue a warning
when it sees [] or {} as a default argument.
What do people think? A misuse or good use of warnings?
--
Steven.
I wonder if it is a check done by Pylint or PyChecker?
It is a check done by pylint
Tim
- Paddy.
--
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--
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function with list argument defaulting to [] - what's going on here???
While trying to write a recursive function involving lists, I came across some (to me) odd behavior which I don't quite understand. Here's a trivial function showing the problem. def f(l, r = []): for itm in l: r.append(itm) print r a = [1,2,3] f(a) [1, 2, 3] f(a) [1, 2, 3, 1, 2, 3] f(a) [1, 2, 3, 1, 2, 3, 1, 2, 3] I know the function is quite artificial, but it's for illustration only. Why is r not being reset to the empty list on subsequent calls? It seems like it should be reinitialized when not explicitly provided. Thanks in advance. Mike -- http://mail.python.org/mailman/listinfo/python-list
Re: function with list argument defaulting to [] - what's going on here???
On 4/14/07, Mike [EMAIL PROTECTED] wrote: While trying to write a recursive function involving lists, I came across some (to me) odd behavior which I don't quite understand. Here's a trivial function showing the problem. from http://docs.python.org/ref/function.html : Default parameter values are evaluated when the function definition is executed. This means that the expression is evaluated once, when the function is defined, and that that same ``pre-computed'' value is used for each call. This is especially important to understand when a default parameter is a mutable object, such as a list or a dictionary: if the function modifies the object (e.g. by appending an item to a list), the default value is in effect modified. -- http://mail.python.org/mailman/listinfo/python-list
Re: function with list argument defaulting to [] - what's going on here???
Thanks, Troy. I never cease to be amazed at what can be discovered by reading the manual! self bangs head on wall Mike Troy Melhase wrote: On 4/14/07, Mike [EMAIL PROTECTED] wrote: While trying to write a recursive function involving lists, I came across some (to me) odd behavior which I don't quite understand. Here's a trivial function showing the problem. from http://docs.python.org/ref/function.html : Default parameter values are evaluated when the function definition is executed. This means that the expression is evaluated once, when the function is defined, and that that same ``pre-computed'' value is used for each call. This is especially important to understand when a default parameter is a mutable object, such as a list or a dictionary: if the function modifies the object (e.g. by appending an item to a list), the default value is in effect modified. -- http://mail.python.org/mailman/listinfo/python-list
Re: function with list argument defaulting to [] - what's going on here???
On Sat, 14 Apr 2007 17:33:11 -0800, Troy Melhase wrote:
On 4/14/07, Mike [EMAIL PROTECTED] wrote:
While trying to write a recursive function involving lists, I came
across some (to me) odd behavior which I don't quite understand. Here's
a trivial function showing the problem.
from http://docs.python.org/ref/function.html :
Default parameter values are evaluated when the function definition is
executed. This means that the expression is evaluated once, when the
function is defined, and that that same ``pre-computed'' value is used
for each call. This is especially important to understand when a
default parameter is a mutable object, such as a list or a dictionary:
if the function modifies the object (e.g. by appending an item to a
list), the default value is in effect modified.
This comes up so often that I wonder whether Python should issue a warning
when it sees [] or {} as a default argument.
What do people think? A misuse or good use of warnings?
--
Steven.
--
http://mail.python.org/mailman/listinfo/python-list
Re: function with list argument defaulting to [] - what's going on here???
Mike [EMAIL PROTECTED] wrote: ... Why is r not being reset to the empty list on subsequent calls? It seems like it should be reinitialized when not explicitly provided. http://www.python.org/doc/faq/general/#why-are-default-values-shared-be tween-objects Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: function with list argument defaulting to [] - what's going on here???
On Apr 15, 3:58 am, Steven D'Aprano
[EMAIL PROTECTED] wrote:
On Sat, 14 Apr 2007 17:33:11 -0800, Troy Melhase wrote:
On 4/14/07, Mike [EMAIL PROTECTED] wrote:
While trying to write a recursive function involving lists, I came
across some (to me) odd behavior which I don't quite understand. Here's
a trivial function showing the problem.
fromhttp://docs.python.org/ref/function.html:
Default parameter values are evaluated when the function definition is
executed. This means that the expression is evaluated once, when the
function is defined, and that that same ``pre-computed'' value is used
for each call. This is especially important to understand when a
default parameter is a mutable object, such as a list or a dictionary:
if the function modifies the object (e.g. by appending an item to a
list), the default value is in effect modified.
This comes up so often that I wonder whether Python should issue a warning
when it sees [] or {} as a default argument.
What do people think? A misuse or good use of warnings?
--
Steven.
I wonder if it is a check done by Pylint or PyChecker?
- Paddy.
--
http://mail.python.org/mailman/listinfo/python-list
Re: function with list argument defaulting to [] - what's going on here???
This comes up so often that I wonder whether Python should issue a warning
when it sees [] or {} as a default argument.
What do people think? A misuse or good use of warnings?
I think Python should reevaluate the default values.
--
mvh Björn
--
http://mail.python.org/mailman/listinfo/python-list
Re: function with list argument defaulting to [] - what's going on here???
On Sun, 15 Apr 2007 05:29:01 +0200, BJörn Lindqvist wrote:
This comes up so often that I wonder whether Python should issue a warning
when it sees [] or {} as a default argument.
What do people think? A misuse or good use of warnings?
I think Python should reevaluate the default values.
That would break code that relies on the current behaviour. That makes it
a maybe for Python 3.0, and an absolute NO!!! for Python 2.x.
--
Steven.
--
http://mail.python.org/mailman/listinfo/python-list
Re: function with list argument defaulting to [] - what's going on here???
Steven D'Aprano [EMAIL PROTECTED] wrote:
On Sun, 15 Apr 2007 05:29:01 +0200, BJörn Lindqvist wrote:
This comes up so often that I wonder whether Python should issue a warning
when it sees [] or {} as a default argument.
What do people think? A misuse or good use of warnings?
I think Python should reevaluate the default values.
That would break code that relies on the current behaviour. That makes it
a maybe for Python 3.0, and an absolute NO!!! for Python 2.x.
If you hope to get any change in Python 3.0, your PEP had better be in
before the end of April -- that's the 3.0 deadline for PEPs.
Alex
--
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Re: X class missing in Python :-) - Re: What's going on here?
John Machin wrote:
robert wrote:
Dale Strickland-Clark wrote:
Python 2.4.2 (#1, Oct 13 2006, 17:11:24)
[GCC 4.1.0 (SUSE Linux)] on linux2
Type help, copyright, credits or license for more information.
a = object()
a
object object at 0xb7bbd438
a.spam = 1
Traceback (most recent call last):
File stdin, line 1, in ?
AttributeError: 'object' object has no attribute 'spam'
class b(object):
...pass
...
a = b()
a
__main__.b object at 0xb7b4dcac
a.spam = 1
What is subclassing adding to the class here? Why can't I assign to
attributes of an instance of object?
Python so dynamic, but it lacks a (builtin) X-class ready for ad-hoc
usage just like dict() :-)
I have in almost every app/toolcore-module this one:
--
class X(object):
def __init__(self,_d={},**kwargs):
kwargs.update(_d)
self.__dict__=kwargs
class Y(X):
def __repr__(self):
return 'Y:%s'%self.__dict__
--
x=X(spam=1)
Maybe X should be renamed to __builtin__.Object ...
Have you considered putting it in one file and *importing* it into
almost every app/toolcore-module?
(yes its in my core python language extension module, which I import
frequently in apps)
Have you considered that others may like to have something a little
more elaborate, like maybe using the pprint module, or that the amount
of data that would spew out might in some cases be so great that they
wouldn't want that every time from repr(), preferring a dump-style
method that wrote to a logfile?
(in X is no repr so far. of course one could make a default repr with short
output. had no frequent needs so far)
IMHO that's one of the enormous number of good points about Python; you
can easily lash up something like that to suit yourself and inject it
into any class you like; there's no central authority tying your hands
behind your back.
its more about the general case, trying things out on the interactive etc.
always - thus when I want speed not suit :-)
very often I need a dummy object and find me always typing class X:pass or
import above tools.
Think this trivial but needed Object() thing is possibly more than a private
sitecustomize-thing. Thats why I wrote here upon seeing others trying object()
which doesn't do what one expects at first.
It wouldn't really tie hands or ? but possibly converse
Robert
--
http://mail.python.org/mailman/listinfo/python-list
Re: What's going on here?
Thanks for the answers. I am informed but I don't feel enlightened. It does strike me as odd that an apparently empty subclass should add extra function to the base class. Not at all obvious. -- Dale Strickland-Clark We are recruiting Python programmers. Please see the web site. Riverhall Systems www.riverhall.co.uk -- http://mail.python.org/mailman/listinfo/python-list
Re: What's going on here?
Dale Strickland-Clark wrote:
Thanks for the answers. I am informed but I don't feel enlightened.
It does strike me as odd that an apparently empty subclass should add extra
function to the base class.
Not at all obvious.
Yes. As said, there is missing a __builtin__.Object
object is not an empty class, but the base builtin-type:
isinstance(int,object)
True
built-in type instances are basically read-only because if ...
(1).spam=1
Traceback (most recent call last):
File interactive input, line 1, in ?
AttributeError: 'int' object has no attribute 'spam'
..would work, that would be very strange.
Maybe in a mud place language like Ruby, where you can jam and scribble
everywhere in the system and in builtins, such things are possible.
I'd propose to add something trivial like
class Object(object):
def __init__(self,_d={},**kwargs):
kwargs.update(_d)
self.__dict__=kwargs
...
to Python. I use such empty (common) class since all time I can think of - and
frequently.
If there would be a common such Empty class in Python you'd have a lot of
advantanges. From ad-hoc instances, OO-dicts to reliable pickling of bunches
of variables etc.
Robert
--
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Re: What's going on here?
Dale Strickland-Clark wrote: Thanks for the answers. I am informed but I don't feel enlightened. It does strike me as odd that an apparently empty subclass should add extra function to the base class. Not at all obvious. Remember that a class definition is syntax sugar for a direct call to type: type(name,bases,clsdict) This constructs and returns the class. It's free to add behaviors even if the clsdict is empty, and that's exactly what it does in this case. type considers the absence of __slots__ in clsdict to be a request for an instance dict, and so it adds one. (Types defined in C aren't created that way, however. I believe C-defined types request an instance dict by reserving space for it in the object structure and setting tp_dictoffset to indicate its offset.) This is not obvious, but it's really the only reasonable way. You can't have the base class of all objects creating dicts for its instances--you wouldn't want every int object to have it's own dict. And you can't have Python class instances not have a dict by default. Carl Banks -- http://mail.python.org/mailman/listinfo/python-list
What's going on here?
Python 2.4.2 (#1, Oct 13 2006, 17:11:24) [GCC 4.1.0 (SUSE Linux)] on linux2 Type help, copyright, credits or license for more information. a = object() a object object at 0xb7bbd438 a.spam = 1 Traceback (most recent call last): File stdin, line 1, in ? AttributeError: 'object' object has no attribute 'spam' class b(object): ...pass ... a = b() a __main__.b object at 0xb7b4dcac a.spam = 1 What is subclassing adding to the class here? Why can't I assign to attributes of an instance of object? -- Dale Strickland-Clark Riverhall Systems - www.riverhall.co.uk -- http://mail.python.org/mailman/listinfo/python-list
Re: What's going on here?
Dale Strickland-Clark wrote: Python 2.4.2 (#1, Oct 13 2006, 17:11:24) a = object() a.spam = 1 Traceback (most recent call last): File stdin, line 1, in ? AttributeError: 'object' object has no attribute 'spam' class B(object): pass a = B() a.spam = 1 What is subclassing adding to the class here? Why can't I assign to attributes of an instance of object? object itself doesn't have a __dict__ slot, so that very small objects (such as points) can be built without that overhead. --Scott David Daniels [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: What's going on here?
What is subclassing adding to the class here? A __dict__: o = object() dir(o) ['__class__', '__delattr__', '__doc__', '__getattribute__', '__hash__', '__init__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__'] class C(object): pass ... c = C() dir(c) ['__class__', '__delattr__', '__dict__', '__doc__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__', '__weakref__'] -- Richie Hindle [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: What's going on here?
Dale Strickland-Clark wrote: Why can't I assign to attributes of an instance of object? it doesn't have any attribute storage. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: What's going on here?
Perhaps this piece of code might explain the behaviour: class C( object ): ... __slots__ = () ... o = C() o.a = 1 Traceback (most recent call last): File input, line 1, in ? AttributeError: 'C' object has no attribute 'a' object behaves like having an implict __slots__ attribute. HTH, Gerald Dale Strickland-Clark schrieb: Python 2.4.2 (#1, Oct 13 2006, 17:11:24) [GCC 4.1.0 (SUSE Linux)] on linux2 Type help, copyright, credits or license for more information. a = object() a object object at 0xb7bbd438 a.spam = 1 Traceback (most recent call last): File stdin, line 1, in ? AttributeError: 'object' object has no attribute 'spam' class b(object): ...pass ... a = b() a __main__.b object at 0xb7b4dcac a.spam = 1 What is subclassing adding to the class here? Why can't I assign to attributes of an instance of object? -- http://mail.python.org/mailman/listinfo/python-list
X class missing in Python :-) - Re: What's going on here?
Dale Strickland-Clark wrote:
Python 2.4.2 (#1, Oct 13 2006, 17:11:24)
[GCC 4.1.0 (SUSE Linux)] on linux2
Type help, copyright, credits or license for more information.
a = object()
a
object object at 0xb7bbd438
a.spam = 1
Traceback (most recent call last):
File stdin, line 1, in ?
AttributeError: 'object' object has no attribute 'spam'
class b(object):
...pass
...
a = b()
a
__main__.b object at 0xb7b4dcac
a.spam = 1
What is subclassing adding to the class here? Why can't I assign to
attributes of an instance of object?
Python so dynamic, but it lacks a (builtin) X-class ready for ad-hoc usage
just like dict() :-)
I have in almost every app/toolcore-module this one:
--
class X(object):
def __init__(self,_d={},**kwargs):
kwargs.update(_d)
self.__dict__=kwargs
class Y(X):
def __repr__(self):
return 'Y:%s'%self.__dict__
--
x=X(spam=1)
Maybe X should be renamed to __builtin__.Object ...
Robert
--
http://mail.python.org/mailman/listinfo/python-list
Re: X class missing in Python :-) - Re: What's going on here?
robert wrote:
Dale Strickland-Clark wrote:
Python 2.4.2 (#1, Oct 13 2006, 17:11:24)
[GCC 4.1.0 (SUSE Linux)] on linux2
Type help, copyright, credits or license for more information.
a = object()
a
object object at 0xb7bbd438
a.spam = 1
Traceback (most recent call last):
File stdin, line 1, in ?
AttributeError: 'object' object has no attribute 'spam'
class b(object):
...pass
...
a = b()
a
__main__.b object at 0xb7b4dcac
a.spam = 1
What is subclassing adding to the class here? Why can't I assign to
attributes of an instance of object?
Python so dynamic, but it lacks a (builtin) X-class ready for ad-hoc
usage just like dict() :-)
I have in almost every app/toolcore-module this one:
--
class X(object):
def __init__(self,_d={},**kwargs):
kwargs.update(_d)
self.__dict__=kwargs
class Y(X):
def __repr__(self):
return 'Y:%s'%self.__dict__
--
x=X(spam=1)
Maybe X should be renamed to __builtin__.Object ...
Have you considered putting it in one file and *importing* it into
almost every app/toolcore-module?
Have you considered that others may like to have something a little
more elaborate, like maybe using the pprint module, or that the amount
of data that would spew out might in some cases be so great that they
wouldn't want that every time from repr(), preferring a dump-style
method that wrote to a logfile?
IMHO that's one of the enormous number of good points about Python; you
can easily lash up something like that to suit yourself and inject it
into any class you like; there's no central authority tying your hands
behind your back.
HTH,
John
--
http://mail.python.org/mailman/listinfo/python-list
Re: what's going on here?
You are along the right lines. Try printing out the content of each URL - one of the pages will match your expression, but has additional instructions... I think you are reaching the end of their false trail when you get None returned from the url. The set of pages themselves are the linked list - each contains a reference to the next element in the sequence. You don't need one to solve the problem, the problem *is* the linked list! An example of a linked list in Python is the following if you are interested: class Element (object): next = None def __init__(self, content): self.content = content class LinkedList (object): first = None last = None def add(self, item): elmnt = Element(item) if not self.first: self.first = elmnt if self.last: self.last.next = elmnt self.last = elmnt def __iter__(self): current = self.first while current: yield current.content current = current.next ll = LinkedList() for i in range(10): ll.add(i) for x in ll: print Res: %s % x -- http://mail.python.org/mailman/listinfo/python-list
Re: what's going on here?
Ant wrote: You are along the right lines. Try printing out the content of each URL - one of the pages will match your expression, but has additional instructions... I think you are reaching the end of their false trail when you get None returned from the url. But the weird thing is that when I tried the same script earlier in the day, it went through about 200+ links before encountering a situation that my script didn't handle. But now when I get this latest error that I posted, it's only going through about 150 links before stopping. The set of pages themselves are the linked list - each contains a reference to the next element in the sequence. You don't need one to solve the problem, the problem *is* the linked list! Interesting! That's good news, and I'm glad I didn't spend hours trying to use one to solve it! :) -- http://mail.python.org/mailman/listinfo/python-list
Re: what's going on here?
John Salerno wrote: Ant wrote: You are along the right lines. Try printing out the content of each URL - one of the pages will match your expression, but has additional instructions... I think you are reaching the end of their false trail when you get None returned from the url. But the weird thing is that when I tried the same script earlier in the day, it went through about 200+ links before encountering a situation that my script didn't handle. But now when I get this latest error that I posted, it's only going through about 150 links before stopping. The set of pages themselves are the linked list - each contains a reference to the next element in the sequence. You don't need one to solve the problem, the problem *is* the linked list! Interesting! That's good news, and I'm glad I didn't spend hours trying to use one to solve it! :) Ok, I'm confused. I ran the script again today (this time at work again) and it worked! I made no changes, so I'm not sure what the issue was. But thank god I'm passed this problem, although I'm sure it only gets worse now! -- http://mail.python.org/mailman/listinfo/python-list
Re: what's going on here?
John Salerno schreef: But thank god I'm passed this problem, although I'm sure it only gets worse now! Yes, I'm afraid it does. I got stuck at puzzle 27 and gave up temporarily. I'm going to try again though when I feel I need a challenge :) -- If I have been able to see further, it was only because I stood on the shoulders of giants. -- Isaac Newton Roel Schroeven -- http://mail.python.org/mailman/listinfo/python-list
what's going on here?
Ok, long story: I'm trying to solve level 4 of the Python Challenge. I hate to post here, but the hint forum over there is dead. Here's the link: http://www.pythonchallenge.com/pc/def/linkedlist.php Apparently you need to use a linked list to solve it, so I read up on them but I still don't understand how to implement one to solve this problem. (Any hints there would be appreciated too.) So I wrote this code instead. It goes to each URL, reads the source code, gets the next number, etc. I realize it uses some terrible tricks, like the regex and the try/except clause, which is way too specific to solve the problem in a general way. Anyway, here's the code: # Python Challenge, level 4 import urllib import re url = 'http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=' pattern = re.compile(r'\bnext nothing is (\d+)') def getNextNum(url): global pattern global nextNum site = urllib.urlopen(url) try: source = site.read() site.close() number = re.search(pattern, source).group(1) except: print nextNum number = str(int(nextNum) / 2) return number nextNum = '12345' f = open(r'C:\Python24\myscripts\challenges\numbers.txt', 'w') try: for x in range(300): f.write(nextNum + '\n') nextNum = getNextNum(url + nextNum) finally: f.close() print url + nextNum Now, I tried this earlier on my work computer and it got as far as printing out two 'nextNum's in the except block, then it appeared that the website timed out and I could no longer access it for a while. I tried later on my home computer and now I keep getting this error: Traceback (most recent call last): File C:\Python24\myscripts\challenges\linked_list.py, line 27, in -toplevel- nextNum = getNextNum(url + nextNum) File C:\Python24\myscripts\challenges\linked_list.py, line 12, in getNextNum site = urllib.urlopen(url) File C:\Python24\lib\urllib.py, line 82, in urlopen return opener.open(url) File C:\Python24\lib\urllib.py, line 190, in open return getattr(self, name)(url) File C:\Python24\lib\urllib.py, line 322, in open_http return self.http_error(url, fp, errcode, errmsg, headers) File C:\Python24\lib\urllib.py, line 339, in http_error return self.http_error_default(url, fp, errcode, errmsg, headers) File C:\Python24\lib\urllib.py, line 579, in http_error_default return addinfourl(fp, headers, http: + url) File C:\Python24\lib\urllib.py, line 871, in __init__ addbase.__init__(self, fp) File C:\Python24\lib\urllib.py, line 818, in __init__ self.read = self.fp.read AttributeError: 'NoneType' object has no attribute 'read' I didn't get this before, so I wonder if it's a website error. There seems to be a problem with getting the source code. It also appears that the script, when run at home, doesn't get as far as the same script when I ran it earlier today at work. So I figure it's either a website problem, or some kind of strange difference between the two computers I'm using (but both use 2.4.3 and nothing else seems different). I hope someone can point me in the right direction. I'm curious why it fails in a different way at home than at work, but also I'd like to know if it's even possible to solve the problem in this way, or if I *have* to use a linked list. -- http://mail.python.org/mailman/listinfo/python-list
Re: what's going on here?
John Salerno wrote: Ok, long story Ok, I guess I should have used a better title for the thread. I hope someone still sees this post! :) -- http://mail.python.org/mailman/listinfo/python-list
what's going on here?
This might be confusing to explain, because it's a question about an example in Beginning Python and I'll try to provide all the info I can. First off, I'm reading a chapter on using the ReportLab modules to create a line graph from a set of data. The first implementation of the program uses a hard-coded list as the data source, the second implementation pulls the data from a URL. In either case, the data is of this format: # year month predicted high low 200412 34.235.233.2 200501 31.534.528.5 (repeated many times) In the first implementation, the data was a list of tuples, each tuple being one row of the data. So grabbing the data was done like this: pred = [row[2]-40 for row in data] high = [row[3]-40 for row in data] etc... We can safely ignore the '-40', that was just for positioning. So the variable for predicted would grab 34.2, 31.5, etc., high would get 35.2, etc. Easy enough. Now, the second implementation does this: for line in urlopen(URL).readlines(): if not line.isspace() and not line[0] in COMMENT_CHARS: data.append(map(float, line.split())) pred = [row[2] for row in data] high = [row[3] for row in data] etc. (URL is the location of the data file online. The if statement just checks for blank lines and lines beginning with certain comment characters, so they can be ignored.) So finally here's my question: If you are using data.append(), doesn't that just put all the numbers into one long list? How are the tuples still being created in this case so that the list comprehensions still work? It seems like there is no longer any 'row' to refer to in data. The only thing I can think of is that each time through the for loop, a new item (tuple or list) is being created in the data list, so that each row of data really is being separated as its own element in the larger list, but that doesn't seem right. Thanks! -- http://mail.python.org/mailman/listinfo/python-list
Re: what's going on here?
[...] So finally here's my question: If you are using data.append(), doesn't that just put all the numbers into one long list? no, append appends extend does what you think How are the tuples still being created in this case so that the list comprehensions still work? It seems like there is no longer any 'row' to refer to in data. why not to fire interpreter to see what happens line1 = 1 2 3 4 line2 = 5 6 7 8 lst = [] lst.append(map(float, line1.split())) lst [[1.0, 2.0, 3.0, 4.0]] lst.append(map(float, line2.split())) lst [[1.0, 2.0, 3.0, 4.0], [5.0, 6.0, 7.0, 8.0]] hth, Daniel -- http://mail.python.org/mailman/listinfo/python-list
Re: what's going on here?
Em Qui, 2006-03-16 às 16:31 +, John Salerno escreveu: So finally here's my question: If you are using data.append(), doesn't that just put all the numbers into one long list? How are the tuples still being created in this case so that the list comprehensions still work? It seems like there is no longer any 'row' to refer to in data. Look the line data.append(map(float, line.split())) In other words: # Suppose line is 200412 34.235.233.2 # for our comments # Creates a list, like [2004, 12, 34.2, 35.2, 33.2] splitted = line.split() # Convert all numbers to floats numbers = map(float, splitted) # It could also be # numbers = [float(x) for x in splitted] # Append the list to the data # ReportLab accept both lists and tuples, so it doesn't matter data.append(numbers) Hope this clarifies your mind, Felipe. -- http://mail.python.org/mailman/listinfo/python-list
Re: what's going on here?
Felipe Almeida Lessa wrote: # Suppose line is 200412 34.235.233.2 # for our comments # Creates a list, like [2004, 12, 34.2, 35.2, 33.2] splitted = line.split() Thanks guys! I think what I forgot was that split() returns a list, so that's when the 'rows' were being created. -- http://mail.python.org/mailman/listinfo/python-list
Re: mod_python: what's going on here?
Robert J. Hansen wrote: I'm not entirely certain comp.lang.python is the proper newsgroup for mod_python questions, but comp.lang.python.web doesn't seem to exist, so... my apologies in advance if this is considered off-topic. I'm attempting to get mod_python 3.1.4/python 2.4.1 working on Apache 2.0.54 running under OS X. Apache was compiled from source with a simple /configure --enable-so --with-mpm=worker ... followed by the make/make install dance. mod_python was almost as simple: ./configure --with-apxs=/usr/local/apache2/bin/apxs \ --with-python=/sw/bin/python2.4 ... followed by the requisite dance. At this point, all's well. The following bits were added to httpd.conf: LoadModule python_module /usr/local/apache2/modules/mod_python.so Directory /usr/local/apache2/htdocs/test AddHandler mod_python .py PythonHandler mptest PythonDebug on /Directory ... one apachectl restart later, Apache was running fine and serving pages. The version string at the bottom of some static pages listed mod_python as being present, so I reckoned that meant it was all installed all right. However, any attempt to serve a mod_python script, mptest.py, from the test subdirectory results in a 500 Internal Server Error. Nothing gets written to error_log, but access_log confirms the 500 was sent. Does anyone have any experience with mod_python on OS X/Apache environments? Can anyone shed some light on 500s that don't leave traces in the error logs, or what precise incantation I need to make mod_python start serving up scripts? Also, if this is not appropriate for this group, does anyone know of a Python group for which this is more appropriate? You will probably get help on this newsgroup, but the mod-python list is pretty helpful, and there's a Python Web-Sig mailing list you can find out about at http://www.python.org/sigs/ if you want. I'm afraid I am new to OS X (and 3,000 miles away from my Mac Mini), so I can't be any help directly with any Mac-dependent issues. But when I first started using mod_python someone (I'm afraid I don't remember who) advised me to use SetHandler rather than AddHandler. Looking at my Windows httpd.conf (2.0.52, so close enough to yours) I see # # # # MOD_PYTHON TESTING AREA # # # # # # Request handler # Directory C:/apache/htdocs/modpy AllowOverride FileInfo SetHandler mod_python PythonHandler mptest PythonDebug On /Directory # # Filter handler # Directory C:/Apache/htdocs/test AllowOverride All SetHandler mod_python #PythonHandler mptest1 #PythonFixupHandler mptest1 PythonLogHandler mptest1 PythonOutputFilter mptest1 CAPITALIZE AddOutputFilter CAPITALIZE .txt .py PythonDebug On /Directory This might at least be enough to start generating sensible error messages. One further possibility is that Apache is using an older Python by default: byte codes vary from version to version, so something horrible might be happening as mod_python tries to execute, but that seems a bit far-fetched when you've got so far. I seem to remember that OS X doesn't supply 2.4 by default: have you added it or overwritten the default Python? Just another base to cover ... regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC http://www.holdenweb.com/ -- http://mail.python.org/mailman/listinfo/python-list
mod_python: what's going on here?
I'm not entirely certain comp.lang.python is the proper newsgroup for mod_python questions, but comp.lang.python.web doesn't seem to exist, so... my apologies in advance if this is considered off-topic. I'm attempting to get mod_python 3.1.4/python 2.4.1 working on Apache 2.0.54 running under OS X. Apache was compiled from source with a simple /configure --enable-so --with-mpm=worker ... followed by the make/make install dance. mod_python was almost as simple: ./configure --with-apxs=/usr/local/apache2/bin/apxs \ --with-python=/sw/bin/python2.4 ... followed by the requisite dance. At this point, all's well. The following bits were added to httpd.conf: LoadModule python_module /usr/local/apache2/modules/mod_python.so Directory /usr/local/apache2/htdocs/test AddHandler mod_python .py PythonHandler mptest PythonDebug on /Directory ... one apachectl restart later, Apache was running fine and serving pages. The version string at the bottom of some static pages listed mod_python as being present, so I reckoned that meant it was all installed all right. However, any attempt to serve a mod_python script, mptest.py, from the test subdirectory results in a 500 Internal Server Error. Nothing gets written to error_log, but access_log confirms the 500 was sent. Does anyone have any experience with mod_python on OS X/Apache environments? Can anyone shed some light on 500s that don't leave traces in the error logs, or what precise incantation I need to make mod_python start serving up scripts? Also, if this is not appropriate for this group, does anyone know of a Python group for which this is more appropriate? -- http://mail.python.org/mailman/listinfo/python-list
