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How to split this string where __ is the delimiter

MATCHES__STRING

To get an output of ['MATCHES', 'STRING']?

For splitting specifically on whitespace, see How do I split a string into a list of words?.

To extract everything before the first delimiter, see Splitting on first occurrence.

To extract everything before the last delimiter, see partition string in python and get value of last segment after colon.

bad_coder
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Hulk
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    http://docs.python.org/library/stdtypes.html#str.split – getekha Aug 13 '10 at 08:50
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    It is worth to read the python standard documents and trying to understand few programs others have made to start to grasp basics of Python. Practise and copying/modifying are great tools to learn language. – Tony Veijalainen Aug 13 '10 at 09:00

5 Answers5

396

You can use the str.split method: string.split('__')

>>> "MATCHES__STRING".split("__")
['MATCHES', 'STRING']
MendelG
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adamk
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    I was wondering, what is the difference between the first example (simply using split()) and the second example (with a for loop)? – EndenDragon Jun 26 '16 at 18:21
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    @EndenDragon The for loop will automatically apply `x.strip()` and return a list of matches without whitespace on either side. The devil is in the details. – Sébastien Vercammen Jun 29 '16 at 13:59
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    Hey, since this is a very popular question, I edited it to ask only 1 specific question and removed the part with the spaces around the delimiter because it wasn't clear what the OP even expected to happen (Since there never was a question in the question). I think the question (and answers) are more useful this way, but feel free to rollback all the edits if you disagree. – Aran-Fey Oct 09 '18 at 14:55
  • Often you just want one part of the `splitted` string. Get it with `'match'.split('delim')[0]` for the first one, etc. – Timo Mar 15 '22 at 12:37
4

You may be interested in the csv module, which is designed for comma-separated files but can be easily modified to use a custom delimiter.

import csv
csv.register_dialect( "myDialect", delimiter = "__", <other-options> )
lines = [ "MATCHES__STRING" ]

for row in csv.reader( lines ):
    ...
Aran-Fey
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Katriel
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3

Besides split and rsplit, there is partition/rpartition. It separates string once, but the way question was asked, it may apply as well.

Example:

>>> "MATCHES__STRING".partition("__")
('MATCHES', '__', 'STRING')

>>> "MATCHES__STRING".partition("__")[::2]
('MATCHES', 'STRING')

And a bit faster then split("_",1):

$ python -m timeit "'validate_field_name'.split('_', 1)[-1]"
2000000 loops, best of 5: 136 nsec per loop

$ python -m timeit "'validate_field_name'.partition('_')[-1]"
2000000 loops, best of 5: 108 nsec per loop

Timeit lines are based on this answer

topin89
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2

When you have two or more elements in the string (in the example below there are three), then you can use a comma to separate these items:

date, time, event_name = ev.get_text(separator='@').split("@")

After this line of code, the three variables will have values from three parts of the variable ev.

So, if the variable ev contains this string and we apply separator @:

Sa., 23. März@19:00@Klavier + Orchester: SPEZIAL

Then, after the split operation the variable

  • date will have value Sa., 23. März
  • time will have value 19:00
  • event_name will have value Klavier + Orchester: SPEZIAL
Gino Mempin
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Sergey Nasonov
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1

For Python 3.8, you actually don't need the get_text method, you can just go with ev.split("@"), as a matter of fact the get_text method is throwing an att. error. So if you have a string variable, for example:

filename = 'file/foo/bar/fox'

You can just split that into different variables with comas as suggested in the above comment but with a correction:

W, X, Y, Z = filename.split('_') 
W = 'file' 
X = 'foo'
Y = 'bar'
Z = 'fox'
Gnai
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