How are glob.glob()'s return values ordered?

user_562769 0
Viewed 202198

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

glob python
12 Answers

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_19306920

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_9306150

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_116412760

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_17918350

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_1340770

I used the built in sorted so solve this problem:

from pathlib import Path

p = Path('/home/my/path')
sorted(list(p.glob('**/*.png')))
user_73006750

Please try this code:

sorted(glob.glob( os.path.join(path, '*.png') ),key=lambda x:float(re.findall("([0-9]+?)\.png",x)[0]))
user_91167090
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