from itertools import imap
from future_builtins import map as fmap # Different name to highlight differences
image = [[1, 2, 3],
[4, 5, 6],
[7, 8, 9]]
list(map(None, *image))
# Out: [(1, 4, 7), (2, 5, 8), (3, 6, 9)]
list(fmap(None, *image))
# Out: [(1, 4, 7), (2, 5, 8), (3, 6, 9)]
list(imap(None, *image))
# Out: [(1, 4, 7), (2, 5, 8), (3, 6, 9)]
image2 = [[1, 2, 3],
[4, 5],
[7, 8, 9]]
list(map(None, *image2))
# Out: [(1, 4, 7), (2, 5, 8), (3, None, 9)] # Fill missing values with None
list(fmap(None, *image2))
# Out: [(1, 4, 7), (2, 5, 8)] # ignore columns with missing values
list(imap(None, *image2))
# Out: [(1, 4, 7), (2, 5, 8)] # dito
list(map(None, *image))
TypeError: 'NoneType' object is not callable
But there is a workaround to have similar results:
def conv_to_list(*args):
return list(args)
list(map(conv_to_list, *image))
# Out: [[1, 4, 7], [2, 5, 8], [3, 6, 9]]