Joining every four strings in a list

Question

I have a list like this:

['Ww','Aa','Bb','Cc','ww','AA','BB','CC']

And continuing in such a pattern, with varying capitals and lowercases. What I want to do is join every four items in this list together. So, the resulting new list (given the one above) would look like this:

['WwAaBbCc', "wwAABBCC']

How would I go about this?

Edited the title. I was going to ask something else and then changed my mind. — Hersh S., Apr 10 '12 at 04:03

score 4 · Accepted Answer · answered Apr 10 '12 at 04:01

4

>>> L = ['Ww','Aa','Bb','Cc','ww','AA','BB','CC']
>>> [''.join(x) for x in zip(*[iter(L)] * 4)]
['WwAaBbCc', 'wwAABBCC']

answered Apr 10 '12 at 04:01

Ignacio Vazquez-Abrams

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Nice, but why not use `map(''.join,zip(*[iter(L)] * 4))`? – jamylak Apr 10 '12 at 04:03
@jamylak: LCs are preferred to `map()` for some reason. – Ignacio Vazquez-Abrams Apr 10 '12 at 04:04
I hate that :D Anyway this is my favorite way although I like `map` – jamylak Apr 10 '12 at 04:10
1

You can read this: http://stackoverflow.com/questions/2233204/how-does-zipitersn-work-in-python – jamylak Apr 10 '12 at 04:21

Mike Axiak · Answer 2 · 2012-04-10T16:13:46.557

3

my_list = ['Ww','Aa','Bb','Cc','ww','AA','BB','CC']
[''.join(my_list[i:i + 4]) for i in range(0, len(my_list), 4)]

edited Apr 10 '12 at 16:13

answered Apr 10 '12 at 04:00

Mike Axiak

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Haha just posted my answer to see that you had posted the exact same solution. +1 – Nolen Royalty Apr 10 '12 at 04:04
here's the error I get: new_Final = [''.join(final[i:i + 4] for i in range(0, len(final), 4)] ^ SyntaxError: invalid syntax (the arrow points to the last bracket) – Hersh S. Apr 10 '12 at 04:09

score 1 · Answer 3 · answered Apr 10 '12 at 04:10

You can use something like this:

def _get_chunks(lVals, size):
    for i in range(0, len(lVals), size):
        yield lVals[i: i + size]

data = ['Ww','Aa','Bb','Cc','ww','AA','BB','CC']


output = [''.join(chunk) for chunk in _get_chunks(data, 4)]
>>> ['WwAaBbCc', 'wwAABBCC']

Joining every four strings in a list

3 Answers3