How to concatenate a list of sublists equally chunked

December 9, 2021

I have a list that contains sublists of two different types of items (for instance, cats and dogs). I also have a function chunk(list, n_sublists) that splits the list into n_sublists of equal size.

Then, i’d like to create a final list that merges the chunked lists from each type. An example:

cats_and_dogs = [ [dog1, dog2, dog3, dog4], [cat1, cat2] ]

splitted_chunks = [[[dog1, dog2], 
                    [dog3, dog4]],
                  [[cat1], 
                  [cat2]]] 

final_merged_sublists = [ [dog1, dog2, cat1], [dog3, dog4, cat2] ]

I hope the example makes it clear. However, i can provide more explanation if needed.

Thanks in advance.

>Solution :

You can do a loop on zip:

list(x+y for x,y in zip(chunk(dogs,2), chunk(cats,2))

Output:

[['dog1', 'dog2', 'cat1'], ['dog3', 'dog4', 'cat2']]

Update: in general, use reduce

from functools import reduce

splitted_chunks = map(lambda x: chunk(x,2), cats_and_dogs)
list(reduce(lambda x,y: x+y, z) for z in zip(*splitted_chunks) )