Splitting a string by list of indices

s = 'long string that I want to split up'indices = [0,5,12,17]parts = [s[i:j] for i,j in zip(indices, indices[1:]+[None])]

returns

['long ', 'string ', 'that ', 'I want to split up']

which you can print using:

print '\n'.join(parts)

Another possibility (without copying indices) would be:

s = 'long string that I want to split up'indices = [0,5,12,17]indices.append(None)parts = [s[indices[i]:indices[i+1]] for i in xrange(len(indices)-1)]

Here is a short solution with heavy usage of the itertools module. The tee function is used to iterate pairwise over the indices. See the Recipe section in the module for more help.

>>> from itertools import tee, izip_longest>>> s = 'long string that I want to split up'>>> indices = [0,5,12,17]>>> start, end = tee(indices)>>> next(end)0>>> [s[i:j] for i,j in izip_longest(start, end)]['long ', 'string ', 'that ', 'I want to split up']

Edit: This is a version that does not copy the indices list, so it should be faster.

You can write a generator if you don't want to make any modifications to the list of indices:

>>> def split_by_idx(S, list_of_indices):...     left, right = 0, list_of_indices[0]...     yield S[left:right]...     left = right...     for right in list_of_indices[1:]:...         yield S[left:right]...         left = right...     yield S[left:]... >>> >>> >>> s = 'long string that I want to split up'>>> indices = [5,12,17]>>> [i for i in split_by_idx(s, indices)]['long ', 'string ', 'that ', 'I want to split up']