How to concatenate a list of sublists equally chunked-CodePudding

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.

CodePudding user response：

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) )

CodePudding user response：

You can use zip and itertools.chain:

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

from itertools import chain
final_merged_sublists = [list(chain.from_iterable(x)) for x in zip(*splitted_chunks)]

Output:

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

NB. To apply chunk on all sublists of the original list of arbitrary size, use map

CodePudding user response：

Just for fun, you can zip the lists and flatten each sublist of subsublists:

def flatten_list(list1):
    out = []
    inside = list1
    while inside:
        x = inside.pop(0)
        if isinstance(x, list):
            inside[0:0] = x
        else:
            out.append(x)
    return out

out = [flatten_list(list(x)) for x in zip(*splitted_chunks)]

Output:

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