如何创建多维索引数组？

Question

I want to create a 3d array where basically the content is identical to the indeces used to access it. So m[2,5] would result in array([2, 5]) . I couldn't find an obvious solution with the numpy functions indices , ogrid , concatenate , etc.

At the moment I'm using this, but was wondering whether there is a solution that makes better use of the API:

a, b = 3, 4
m = np.ones((a, b, 2))
for x in range(a):
    m[x,:, 1] = np.array(range(b))
for y in range(b):
    m[:,y,0] = np.array(range(a))

Answer 1

Try np.mgrid :

a, b = 3, 4
m = np.mgrid[:a,:b].transpose(1,2,0)

print(m[1,2])
# array([1, 2])