Python - Dynamically changing regex not matching all patterns in a list

Question

So the end goal is to sort through some audiobook tracks that are haphazardly thrown into a folder when ripped on my computer.

I am first separating all tracks with the same numbers. In the end, I know I'll need user input to decide which discs get the track numbers they don't all share, but I could make quick work of that too.

I've used regex before, so I thought, I got this, but am hung up on why the code below ceases to match tracks numbered 6 and 7, and the only difference I can see is that there is not 3 of them.

I guess I'm also not sure if I am using the for loop correctly.

All the needed code is below.

The "print tracks" command at the bottom should print all files in order, and "print file_names" should be empty, but neither of those things is true.

I get this:

[['01. Track 1 (19).mp3', '01. Track 1 (20).mp3', '01. Track 1 (21).mp3'], ['02. Track 2 (21).mp3', '02. Track 2 (20).mp3', '02. Track 2 (19).mp3'], ['03. Track 3 (21).mp3', '03. Track 3 (20).mp3', '03. Track 3 (19).mp3'], ['04. Track 4 (19).mp3', '04. Track 4 (20).mp3', '04. Track 4 (21).mp3'], ['05. Track 5 (19).mp3', '05. Track 5 (20).mp3', '05. Track 5 (21).mp3']]
['07. Track 7 (19).mp3', '06. Track 6 (20).mp3', '06. Track 6 (19).mp3']

Why isn't the second printed list completely sorted into the first?

Any help would be stupendous.

import re

file_names = ['07. Track 7 (19).mp3', '01. Track 1 (19).mp3', '01. Track 1 (20).mp3', '01. Track 1 (21).mp3', '02. Track 2 (21).mp3', '03. Track 3 (21).mp3', '02. Track 2 (20).mp3', '04. Track 4 (19).mp3', '02. Track 2 (19).mp3', '04. Track 4 (20).mp3', '05. Track 5 (19).mp3', '05. Track 5 (20).mp3', '04. Track 4 (21).mp3', '06. Track 6 (20).mp3', '03. Track 3 (20).mp3', '05. Track 5 (21).mp3', '06. Track 6 (19).mp3', '03. Track 3 (19).mp3']


def compile_regex(num):
    num_str = str(num)
    regex = ".*track ?" + num_str + ".*"
    track_test = re.compile(regex, re.I)
    return track_test

def matchfiles(file_names,track_test):
    matches = []
    for track in file_names:
        if track_test.search(track):
            matches.append(track)
    return matches

def removetracks(file_names,matches):
    for track in matches:
        file_names.remove(track)

    return (file_names)

def sortfiles(file_names):
    num = 1
    tracks = []
    track_test = compile_regex(num)
    num_tracks = len(file_names)

    for file in file_names:

        matches = matchfiles(file_names,track_test)
        if matches:
            num += 1
            track_test = compile_regex(num)
            tracks.append(matches)
            file_names = removetracks(file_names,matches)
    print tracks
    print file_names

if __name__ == "__main__":
    sortfiles(file_names)

TomR8 · Accepted Answer · 2016-11-20 11:10:28Z

2

There is an issue with this line in your code:

    for file in file_names:

As you update file_names during your computation, the behavior of this loop is unpredictable.

Here is a working variant of your sortfiles routine (with some unnecessary code removed):

def sortfiles(file_names):
    num = 0
    tracks = []
    while file_names != []:
        num += 1
        track_test = compile_regex(num)
        matches = matchfiles(file_names, track_test)
        if matches:
            tracks.append(matches)
            file_names = removetracks(file_names, matches)

    print (tracks)
    print (file_names)

edited Nov 20, 2016 at 11:10

answered Nov 20, 2016 at 10:55

TomR8

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