更改矩阵中的元素顺序（python）

Question

mat = [[0],[1],[2]]

I want to "cycle" the element of my matrix like this:

mat = [[2],[0],[1]]
mat = [[1],[2],[0]]
mat = [[0],[1],[2]]
...

How can I change the index of these elements to loop like above?

Answer 1

>>> for i in xrange(len(mat)):
...  print(mat[i:] + mat[:i])
... 
[[0], [1], [2]]
[[1], [2], [0]]
[[2], [0], [1]]

Answer 2

For large lists using a combination of deque and a generator will be most efficient:

>>> import collections.deque
>>> def list_cycler_gen(lst):
        q = collections.deque(lst,len(lst))
        while True:
            q.appendleft(q.pop())
            yield list(q)

>>> gen = list_cycler_gen([[0],[1],[2]])
>>> gen.next()
[[2], [0], [1]]
>>> gen.next()
[[1], [2], [0]]
>>> gen.next()
[[0], [1], [2]]

This will work with anything you place in the list. Also, if you would have wanted to cycle in the other direction, you could replace the first loop line with:

q.append(q.popleft())