Assign values to numpy.array

Question

Let say we create this np.array:

A = np.arange(12).reshape(3, 4)

So, A is:

array([[ 0,  1,  2,  3],
       [ 4,  5,  6,  7],
       [ 8,  9, 10, 11]])

I would like to assign some values to A like that:

A[[0,2]][:,[1,3]] = 9999

In order to obtain:

array([[ 0,  9999,  2,  9999],
       [ 4,  5,  6,  7],
       [ 8,  9999, 10, 9999]])

But this doesn't work. What is the proper way to do it?

Thanks

Answer 1

您可以使用np.ix_来获取那些开放式网格物体，当这些网格物体用于索引到数组中时将被broadcasted ，因此可以用于为其分配值，如下所示-

A[np.ix_([0,2],[1,3])] = 9999