Sorting directory contents

[Jussi Salmela]

Wolfgang Draxinger kirjoitti:
> Jussi Salmela wrote:
> 
>> I'm not claiming the following to be more elegant, but I would
>> do it like this (not tested!):
>>
>> src_file_paths = dict()
>> prefix = sourcedir + os.sep
>> for fname in os.listdir(sourcedir):
>>      if match_fname_pattern(fname):
>>          fpath = prefix + fname
>>          src_file_paths[os.stat(fpath).st_mtime] = fpath
>> for ftime in src_file_paths.keys().sort():
>>          read_and_concatenate(src_file_paths[ftime])
> 
> Well, both versions, mine and yours won't work as it was written
> down, as they neglegt the fact, that different files can have
> the same st_mtime and that <listtype>.sort() doesn't return a
> sorted list.
> 
> However this code works (tested) and behaves just like listdir,
> only that it sorts files chronologically, then alphabetically.
> 
> def listdir_chrono(dirpath):
>         import os
>         files_dict = dict()
>         for fname in os.listdir(dirpath):
>                 mtime = os.stat(dirpath+os.sep+fname).st_mtime
>                 if not mtime in files_dict:
>                         files_dict[mtime] = list()
>                 files_dict[mtime].append(fname)
>         
>         mtimes = files_dict.keys()
>         mtimes.sort()
>         filenames = list()
>         for mtime in mtimes:
>                 fnames = files_dict[mtime]
>                 fnames.sort()
>                 for fname in fnames:
>                         filenames.append(fname)
>         return filenames
> 
> Wolfgang Draxinger

More elegant or not ... I did it MY WAYYYY!!! (and tested this time 
really carefully;)):

#-------------------------------
def listdir_chrono_2(dirpath):
         import os
         files_dict = {}
         prefix = dirpath + os.sep
         for fname in os.listdir(dirpath):
                 mtime = os.stat(prefix + fname).st_mtime
                 files_dict.setdefault(mtime, []).append(fname)

         mtimes = sorted(files_dict.keys())
         filenames = []
         for mtime in mtimes:
                 filenames += sorted(files_dict[mtime])
         return filenames

firstLst = listdir_chrono('.')
secondLst = listdir_chrono_2('.')
if firstLst == secondLst: print 'OK'
else: print 'ERROR!!!'
#-------------------------------

I keep taking the "dirpath + os.sep" part out of the loop because it is 
a loop invariant and doesn't have to be inside the loop.

Cheer