I currently have a list of filenames in a txt file and I am trying to sort them. The first this I am trying to do is split them into a list since they are all in a single line. There are 3 types of file types in the list. I am able to split the list but I would like to keep the delimiters in the end result and I have not been able to find a way to do this. The way that I am splitting the files is as follows:
import re
def breakLines():
unsorted_list = []
file_obj = open("index.txt", "rt")
file_str = file_obj.read()
unsorted_list.append(re.split('.txt|.mpd|.mp4', file_str))
print(unsorted_list)
breakLines()
I found DeepSpace's answer to be very helpful here Split a string with "(" and ")" and keep the delimiters (Python) , but that only seems to work with single characters.
EDIT:
Sample input:
file_name1234.mp4file_name1235.mp4file_name1236.mp4file_name1237.mp4
Expected output:
file_name1234.mp4
file_name1235.mp4
file_name1236.mp4
file_name1237.mp4
In re.split
, the key is to parenthesise the split pattern so it's kept in the result of re.split
. Your attempt is:
>>> s = "file_name1234.mp4file_name1235.mp4file_name1236.mp4file_name1237.mp4"
>>> re.split('.txt|.mpd|.mp4', s)
['file_name1234', 'file_name1235', 'file_name1236', 'file_name1237', '']
okay that doesn't work (and the dots would need escaping to be really compliant with what an extension is), so let's try:
>>> re.split('(\.txt|\.mpd|\.mp4)', s)
['file_name1234',
'.mp4',
'file_name1235',
'.mp4',
'file_name1236',
'.mp4',
'file_name1237',
'.mp4',
'']
works but this is splitting the extensions from the filenames and leaving a blank in the end, not what you want (unless you want an ugly post-processing). Plus this is a duplicate question: In Python, how do I split a string and keep the separators?
But you don't want re.split
you want re.findall
:
>>> s = "file_name1234.mp4file_name1235.mp4file_name1236.mp4file_name1237.mp4"
>>> re.findall('(\w*?(?:\.txt|\.mpd|\.mp4))',s)
['file_name1234.mp4',
'file_name1235.mp4',
'file_name1236.mp4',
'file_name1237.mp4']
the expression matches word characters (basically digits, letters & underscores), followed by the extension. To be able to create a OR, I created a non-capturing group inside the main group.
If you have more exotic file names, you can't use \\w
anymore but it still reasonably works (you may need some str.strip
post-processing to remove leading/trailing blanks which are likely not part of the filenames):
>>> s = " file name1234.mp4file-name1235.mp4 file_name1236.mp4file_name1237.mp4"
>>> re.findall('(.*?(?:\.txt|\.mpd|\.mp4))',s)
[' file name1234.mp4',
'file-name1235.mp4',
' file_name1236.mp4',
'file_name1237.mp4']
So sometimes you think re.split
when you need re.findall
, and the reverse is also true.
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