How is Pythons glob glob ordered

Question

I have written the following Python code     usr bin python   - - coding  utf-8 - -  import os  glob  path     home my path  for infile in glob glob  os path join path     png          print infile  Now I get this   home my path output0352 png  home my path output0005 png  home my path output0137 png  home my path output0202 png  home my path output0023 png  home my path output0048 png  home my path output0069 png  home my path output0246 png  home my path output0071 png  home my path output0402 png  home my path output0230 png  home my path output0182 png  home my path output0121 png  home my path output0104 png  home my path output0219 png  home my path output0226 png  home my path output0215 png  home my path output0266 png  home my path output0347 png  home my path output0295 png  home my path output0131 png  home my path output0208 png  home my path output0194 png  In which way is it ordered  To clarify  I am not interested in ordering - I know sorted  I want to know in which order it comes by default  It might help you to get my ls -l output  -rw-r--r-- 1 moose moose 627669 2011-07-17 17 26 output0005 png -rw-r--r-- 1 moose moose 596417 2011-07-17 17 26 output0023 png -rw-r--r-- 1 moose moose 543639 2011-07-17 17 26 output0048 png -rw-r--r-- 1 moose moose 535384 2011-07-17 17 27 output0069 png -rw-r--r-- 1 moose moose 543216 2011-07-17 17 27 output0071 png -rw-r--r-- 1 moose moose 561776 2011-07-17 17 27 output0104 png -rw-r--r-- 1 moose moose 501865 2011-07-17 17 27 output0121 png -rw-r--r-- 1 moose moose 547144 2011-07-17 17 27 output0131 png -rw-r--r-- 1 moose moose 530596 2011-07-17 17 27 output0137 png -rw-r--r-- 1 moose moose 532567 2011-07-17 17 27 output0182 png -rw-r--r-- 1 moose moose 553562 2011-07-17 17 27 output0194 png -rw-r--r-- 1 moose moose 574065 2011-07-17 17 27 output0202 png -rw-r--r-- 1 moose moose 552197 2011-07-17 17 27 output0208 png -rw-r--r-- 1 moose moose 559809 2011-07-17 17 27 output0215 png -rw-r--r-- 1 moose moose 549046 2011-07-17 17 27 output0219 png -rw-r--r-- 1 moose moose 566661 2011-07-17 17 27 output0226 png -rw-r--r-- 1 moose moose 561678 2011-07-17 17 27 output0246 png -rw-r--r-- 1 moose moose 525550 2011-07-17 17 27 output0266 png -rw-r--r-- 1 moose moose 565715 2011-07-17 17 27 output0295 png -rw-r--r-- 1 moose moose 568381 2011-07-17 17 28 output0347 png -rw-r--r-- 1 moose moose 532768 2011-07-17 17 28 output0352 png -rw-r--r-- 1 moose moose 535818 2011-07-17 17 28 output0402 png  It is not ordered by filename or size  Other links  glob  ls

User · Answer

At least in Python3 you also can do this:

import os, re, glob

path = '/home/my/path'
files = glob.glob(os.path.join(path, '*.png'))
files.sort(key=lambda x:[int(c) if c.isdigit() else c for c in re.split(r'(\d+)', x)])
for infile in files:
    print(infile)

This should lexicographically order your input array of strings (e.g. respect numbers in strings while ordering).

User · Answer

I had a similar issue  glob was returning a list of file names in an arbitrary order but I wanted to step through them in numerical order as indicated by the file name  This is how I achieved it   My files were returned by glob something like   myList     c  tmp x 123 csv    c  tmp x 44 csv    c  tmp x 101 csv    c  tmp x 102 csv    c  tmp x 12 csv     I sorted the list in place  to do this I created a function   def sortKeyFunc s       return int os path basename s   -4     This function returns the numeric part of the file name and converts to an integer I then called the sort method on the list as such   myList sort key sortKeyFunc    This returned a list as such     c  tmp x 12 csv    c  tmp x 44 csv    c  tmp x 101 csv    c  tmp x 102 csv    c  tmp x 123 csv

User · Answer

It is probably not sorted at all and uses the order at which entries appear in the filesystem  i e  the one you get when using ls -U   At least on my machine this produces the same order as listing glob matches

User · Answer

From  Johan La Rooy s solution  sorting the images using sorted glob glob    png    does not work for me  the output list is still not ordered by their names    However  the sorted glob glob    png    key os path getmtime  works perfectly   I am a bit confused how can sorting by their names does not work here   Thank  Martin Thoma for posting this great question and  Johan La Rooy for the helpful solutions

User · Answer

If you re wondering about what glob glob has done on your system in the past and cannot add a sorted call  the ordering will be consistent on Mac HFS  filesystems and will be traversal order on other Unix systems  So it will likely have been deterministic unless the underlying filesystem was reorganized which can happen if files were added  removed  renamed  deleted  moved  etc

User · Answer

Please try this code   sorted glob glob  os path join path     png     key lambda x float re findall    0-9      png  x  0

User · Answer

Order is arbitrary  but there are several ways to sort them  One of them is as following    First  get the files  import glob import re files  glob glob1 img folder     output image format    if you want sort files according to the digits included in the filename  you can do as following  files   sorted files  key lambda x float re findall    d    x  0

User · Answer

my file name is   0 male 0 wav    0 male 2 wav      0 male 30 wav       1 male 0 wav    1 male 2 wav      1 male 30 wav       8 male 0 wav    8 male 2 wav      8 male 30 wav   when I wav read files  I want to read them in a sorted torder  i e    0 male 0 wav   0 male 1 wav   0 male 2 wav       0 male 30 wav   1 male 0 wav   1 male 1 wav   1 male 2 wav       1 male 30 wav  so this is how I did it   Just take all files start with  0    as an example  Others you can just put it in a loop      import scipy io wavfile as wav import glob  from os path import isfile  join   get all the file names in file names  THe order is totally messed up file names    f for f in listdir audio folder dir  if isfile join audio folder dir  f   and   wav  in f    find files that belongs to  0    group filegroup0   glob glob audio folder dir   0      now you get sorted files in group  0    by the last number in the filename filegroup0   sorted filegroup0  key getKey   def getKey filename       file text name   os path splitext os path basename filename     you get the file s text name without extension     file last num   os path basename file text name 0   split        you get three elements  the last one is the number  You want to sort it by this number     return int file last num 2     That s how I did my particular case  Hope it s helpful

User · Answer

By checking the source code of glob glob you see that it internally calls os listdir  described here   http   docs python org library os html highlight os listdir os listdir  Key sentence  os listdir path  Return a list containing the names of the entries in the directory given by path  The list is in arbitrary order  It does not include the special entries     and      even if they are present in the directory   Arbitrary order

User · Answer

Order is arbitrary  but you can sort them yourself  If you want sorted by name   sorted glob glob    png      sorted by modification time   import os sorted glob glob    png    key os path getmtime    sorted by size   import os sorted glob glob    png    key os path getsize    etc

User · Answer

glob glob   is a wrapper around os listdir   so the underlaying OS is in charge for delivering the data  In general  you can not make an assumption on the ordering here  The basic assumption is  no ordering  If you need some sorting  sort on the application level

[python] How is Pythons glob.glob ordered?

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