30秒学会 Python 片段 – merge

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.

代码实现

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

使用样例

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]]