Python: Split a string at uppercase letters

Question

What is the pythonic way to split a string before the occurrences of a given set of characters?

For example, I want to split 'TheLongAndWindingRoad' at any occurrence of an uppercase letter (possibly except the first), and obtain ['The', 'Long', 'And', 'Winding', 'Road'].

Edit: It should also split single occurrences, i.e. from 'ABC' I'd like to obtain ['A', 'B', 'C'].

Answer 1

Unfortunately it's not possible to split on a zero-width match in Python. But you can use re.findall instead:

>>> import re
>>> re.findall('[A-Z][^A-Z]*', 'TheLongAndWindingRoad')
['The', 'Long', 'And', 'Winding', 'Road']
>>> re.findall('[A-Z][^A-Z]*', 'ABC')
['A', 'B', 'C']

Answer 2

import re
filter(None, re.split("([A-Z][^A-Z]*)", "TheLongAndWindingRoad"))

Answer 3

>>> import re
>>> re.findall('[A-Z][a-z]*', 'TheLongAndWindingRoad')
['The', 'Long', 'And', 'Winding', 'Road']

>>> re.findall('[A-Z][a-z]*', 'SplitAString')
['Split', 'A', 'String']

>>> re.findall('[A-Z][a-z]*', 'ABC')
['A', 'B', 'C']

If you want "It'sATest" to split to ["It's", 'A', 'Test'] change the rexeg to "[A-Z][a-z']*"

Answer 4

Alternative solution (if you dislike explicit regexes):

s = 'TheLongAndWindingRoad'

pos = [i for i,e in enumerate(s) if e.isupper()]

parts = []
for j in xrange(len(pos)):
    try:
        parts.append(s[pos[j]:pos[j+1]])
    except IndexError:
        parts.append(s[pos[j]:])

print parts

Answer 5

A variation on @ChristopheD 's solution

s = 'TheLongAndWindingRoad'

pos = [i for i,e in enumerate(s+'A') if e.isupper()]
parts = [s[pos[j]:pos[j+1]] for j in xrange(len(pos)-1)]

print parts

Answer 6

Here is an alternative regex solution. The problem can be reprased as "how do I insert a space before each uppercase letter, before doing the split":

>>> s = "TheLongAndWindingRoad ABC A123B45"
>>> re.sub( r"([A-Z])", r" \1", s).split()
['The', 'Long', 'And', 'Winding', 'Road', 'A', 'B', 'C', 'A123', 'B45']

This has the advantage of preserving all non-whitespace characters, which most other solutions do not.