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30-seconds-of-code/snippets/merge.md
Isabelle Viktoria Maciohsek b475f10929 Rename zip.md to merge.md
Update description
2020-04-13 19:09:12 +03:00

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title, tags
title tags
merge list,math,advanced

Merges two or more lists into a list of lists, combining elements from each of the input lists based on their positions.

Use max combined with list comprehension to get the length of the longest list in the arguments. Use range() in combination with the max_length variable to loop as many times as there are elements in the longest list. If a list is shorter than max_length, use fill_value for the remaining items (defaults to None).

zip() and itertools.zip_longest() provide similar functionality to this snippet.

def merge(*args, fill_value=None):
  max_length = max([len(lst) for lst in args])
  result = []
  for i in range(max_length):
    result.append([
      args[k][i] if i < len(args[k]) else fill_value for k in range(len(args))
    ])
  return result
merge(['a', 'b'], [1, 2], [True, False]) # [['a', 1, True], ['b', 2, False]]
merge(['a'], [1, 2], [True, False]) # [['a', 1, True], [None, 2, False]]
merge(['a'], [1, 2], [True, False], fill_value = '_') # [['a', 1, True], ['_', 2, False]]