CODEWITHSUNDEEP
pythonstringlistconcatenation
excelsior
excelsior

Reputation: 95

Is there a way to join every n elements of a list

Say I have a list of 26 elements, each a letter of the alphabet as below:

alphabets = ['a', 'b', ... , 'y', 'z']

My objective is to join every 5 elements iteratively, yielding:

combined_strings = ['abcde', 'bcdef', ... 'vwxyz']

I've tried: 

combined_strings = []
for i, k in enumerate(alphabets):
    temp_string = k[i] + k[i+1] + k[i+2] + k[i+3] + k[i+4]
    combined_strings.append(temp_string)

but I am met with IndexError: List index out of range

Upvotes: 1

Views: 1056

Answers (4)

Elan kumanan
Elan kumanan

Reputation: 1

Try below this.

import string
li = list(string.ascii_lowercase);
liRes = []
for i in range(0,22):
    liRes.append("".join(li[i:i+5]))
print(liRes)

Upvotes: 0

kaya3
kaya3

Reputation: 51162

It's more convenient to use a string than a list for this purpose, because you can slice a string to extract a substring. You can also import ascii_lowercase from the string module rather than writing it out yourself.

>>> from string import ascii_lowercase as alphabet
>>> [ alphabet[i:i+5] for i in range(len(alphabet) - 4) ]
['abcde', 'bcdef', 'cdefg', 'defgh', 'efghi', 'fghij', 'ghijk', 'hijkl',
 'ijklm', 'jklmn', 'klmno', 'lmnop', 'mnopq', 'nopqr', 'opqrs', 'pqrst',
 'qrstu', 'rstuv', 'stuvw', 'tuvwx', 'uvwxy', 'vwxyz']

Note that the range should go up to len(alphabet) - 4 (exclusive) so that the last substring has the full length of 5.

Upvotes: 0

Austin
Austin

Reputation: 26057

You are using enumerate in wrong way. enumerate gives both index and the element at that index, so k[i] does not make any sense. Additionally, iterating over the full length causes IndexError as then you will be accessing elements at 27, 28, 29, 30 which are non-existent.

You can correct your code to:

combined_strings = []
for i in range(len(alphabets)-4):
    temp_string = alphabets[i] + alphabets[i+1] + alphabets[i+2] + alphabets[i+3] + alphabets[i+4]
    combined_strings.append(temp_string)

Upvotes: 1

mattyx17
mattyx17

Reputation: 826

you are going too far in the list, your i will go all the way to i=26 and then you have no 27th, 28th, 29th or 30th letter

you could do something like:

combined_strings = ["".join([alphabet[i], alphabet[i+1], alphabet[i+2], alphabet[i+3], alphabet[i+4]]) for i in range(len(alphabet) - 4)]

Upvotes: 0

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