[Tutor] sorting os.listdir.

[Gerrit Holl]

Hi Thomas,

Thomas CLive Richards schreef op donderdag 15 mei om 14:00:05 +0000:
> IS there a reason os.listdir doesn't sort it's output? It does seem a little silly.

It is not necessary, and sometimes it may take a lot of resources.
Imagine listing the contents of a very large directory: sorting
approx. 10.000 filenames may be very time-consuming.

> this function will call os.listdir, and then sort through the output, according to the sort parameter. possible sort parameters should include alphanumeric, numeric, ascii (just takes the ascii values of the charecter).

You may want to use cmp for that. It may be better to pass a function
as second argument, like a default list sort does.

Your code may look like (UNTESTED):
def sortedlistdir(d, cmpfunc=cmp):
    l = os.listdir(d)
    l.sort(cmpfunc)
    return l

> hmmm.. isn't there some sort of builtin sort() function somewhere?? only it's not in the builtins section of the docs.... or maybe that was some other language... bah.. too tired :-)

It is available as a list method:

http://www.python.org/dev/doc/devel/lib/typesseq-mutable.html

Here, all list methods are documented. Further, the way .sort()
works is explained, and it is exactly what you need.

You may want to write you own cmp() functions for sorting numeric, because
as far as I know, this does not exist yet, at least not in the standard
library (it may be a good exercise anyway).

yours,
Gerrit.

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