Iterator of list of list of iterables

问题

I would like to iterate of a list of list of Iterables in Python3.

Stated differently, I have a matrix of iterables and I would like to loop through and get at each iteration a matrix of values. More concretely, I have several files (the rows) which have multiple versions of them (the columns) and I would like at each iteration, get a tuple/matrix containing the first line of all my files and so on.

So, given something like this

a = [
  [iter(range(1,10)), iter(range(11,20)), iter(range(21,30))],
  [iter(range(101,110)), iter(range(111,120)), iter(range(121,130))]
]

I would like to to

for sources_with_their_factors in MAGIC_HERE(a):
  print(sources_with_their_factors)

and get

((1,11,21), (101,111,121))
((2,12,22), (102,112,122))
…

I tried

for b in zip(zip(*zip(*a))):
    ...:     print(b)
    ...:
((<range_iterator object at 0x2b688d65b630>, <range_iterator object at 0x2b688d65b7e0>, <range_iterator object at 0x2b688d65b540>),)
((<range_iterator object at 0x2b688d65ba50>, <range_iterator object at 0x2b688d65b6f0>, <range_iterator object at 0x2b688d65b0c0>),)

But it isn’t iterating my ranges.

回答1:

Obviously you can zip the iterators in each sublist together, you're just missing how to zip the resulting iterators together. I would unpack a generator expression:

for t in zip(*(zip(*l) for l in a)):
    print(t)

((1, 11, 21), (101, 111, 121))
((2, 12, 22), (102, 112, 122))
...

回答2:

Why not just use indexes?

for i in range(len(a[0][0])):
    tupA = (a[0][0][i], a[0][1][i], a[0][2][i])
    tupB = (a[1][0][i], a[1][1][i], a[1][2][i])
    print((tupA, tupB))

EDIT: this is a simple way - the way I ( a simpleton ) would do it. zip will be much more elegant and effective.

来源：https://stackoverflow.com/questions/54633091/iterator-of-list-of-list-of-iterables

标签

python

python-3.x

iterator

iterable