Question

I’m pretty sure that there’s such question..

Here’s the issue – I want to split a string, using some specified chars as delimiters, but I also want the substrings to have length, close to the specified.

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Real world example – split long subtitles lines.

Example:

1234,asd dsa qwerty 567,

I want to split the line to a number of lines with max length, let’s say 10, but I don’t want to “split” words. So, this should become:

1234,asd
dsa qwerty 
567, 

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Of course, I can split the lines by delimiters and then concatenate them again, till I reach the desired length, but this will be terribly slow.

I thought about using str.find (and use the returned position) but it can’t work with regex (because of the different delimiters – ., ,, ;, \n, , etc.).

I think about re.findall, but I can’t think of an regex. I thought something about something like

(.*){, max_len}\s

with re.S, but it’s obviously not working. There should be some tricky way..

Answer 1

The following code splits your string as desired at spaces with a width of 10:

import re
r = "1234,asd dsa qwerty 567,"
p = re.compile("(.{,10})($|\s)")
r = p.sub("\\1\n", r)

In this case it produces output

1234,asd
dsa qwerty
567,

when split with width 5 you get

1234,asd
dsa
qwerty
567,

You can see, that words are never split with this method.

If you like other delimiters just replace “\s” with the desired regular expression.