Split string by index python

I want to split a string by a list of indices, where the split segments begin with one index and end before the next one.

Example:

s = 'long string that I want to split up'
indices = [0,5,12,17]
parts = [s[index:] for index in indices]
for part in parts:
    print part

This will return:

long string that I want to split up
string that I want to split up
that I want to split up
I want to split up

I'm trying to get:

long
string
that
I want to split up

smci

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asked Jun 1, 2012 at 13:43

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]]

answered Jun 1, 2012 at 13:45

eumiroeumiro

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10

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.

flywire

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answered Jun 1, 2012 at 13:52

schlamarschlamar

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3

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']

answered Aug 3, 2019 at 22:18

Zhou ShaoZhou Shao

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0

Another solution [a bit more readable]:

parts=[]; i2=len[s]  #--> i1 and i2 are 'startIndex' and 'endIndex'

for i1 in reversed[indices]: parts.append[ s[i1:i2] ];  i2=i1

parts.reverse[]

This reverses the indices and therefore starts splitting from the last index position to the 'endIndex' i2 [which is updated in every loop].

Of course the elements are in the wrong order than. That's why I reversed the result array at the end.

I think for beginners this is a bit more readable than the accepted answer.

answered Jul 21 at 21:10

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