Set order using glob.glob

Question

I want to set my own order when my script open files but glob.glob default for opening files is random.

I have the following files: 'fish.txt', 'expo.txt', 'random.txt'.

This is a small-scale example of all of my files, I want to set my order.

I have the written the normal way to open files with glob.glob

#! /usr/bin/env python
import sys, os, glob
mylist = ['fish.txt','random.txt', 'expo.txt']
def sorter(item):
    for item in mylist:
        return item

for file in sorted(glob.glob('*.txt'), key = sorter):
     print(file)

My desired​ output would be:

fish.txt

random.txt

expo.txt

Solution 1

You can use sorted(list) to sort your file names before iterating over them:

#!/usr/bin/env python
import sys, os, glob

def sorter(item):
    """Get an item from the list (one-by-one) and return a score for that item."""
    return item[1]

files = sorted(glob.glob('*.txt'), key=sorter)
for file in files:
     print(file)

Here, it sorts by the second letter in the file name. Change the sorter() function to how you want to sort your file list.

To sort alphabetically, you don't need the key=sorter part, because that's the default behavior of sorted() with a list of strings. So then it would become:

files = sorted(glob.glob('*.txt'))
for file in files:
     print(file)

Solution 2

You can sort the entries from glob. You may use the default sorting or choose an algorithm of your own:

Simple usage:

#! /usr/bin/env python
import sys, os, glob

for file in sorted(glob.glob('*.txt')):
     print(file)

'sorted' manual: https://python-reference.readthedocs.io/en/latest/docs/functions/sorted.html

Comments

[iz_]

How do you want the order to be set? Sorted?

[BlackBear]

why do you sort on the second character..?

[user8181134]

It was just an example of what's possible. You should change the sorter() function to an algoritthm how you want to sort the files. If you just want to sort alphabetically, you can ommit the key=sorter part.

[gusa10]

@BlackBear , thank you! . Can you help me to complete the script? I have this ( It does not work): def sorter(item): for item in mylist: return item. I created mylist [] in the order I want

[user8181134]

The sorter() function receives one item (one filename in this case) at each call, not the whole list. So to sort alphabetically, it would just return the filename, which is why you can omit the key=sorter from the sorted(...) function call then.

[gusa10]

@user8181134 I do not want to sort alphabetically but I want to input my own order. That is why I create myList = [] in my expected order. My idea was that if I read each value of myList, each value will be read in the same order as they appear in the list.

[user8181134]

For a custom sorting algorithm, your sorter() function should return a number as a score for the item. The item with the lowest score is placed in the first spot in the list

[Sharad]

What's the logic you want for ordering? You need to implement that logic in 'def sorter()' above - it's currently returning items in the same order it received.

[gusa10]

thanks!, my question is more related about setting my own order based on the order of a list I create. make sense?