np.ndarray 的增量维度

Question

I want to increment the dimension of an ndarray like this:

from r = [[1 2]
          [3 4]] 

to r = [[1 2 0]
        [3 4 0]
        [0 0 0]]

if I use r.resize((3, 3), refcheck=False) i get:

[[1 2 3]
 [4 0 0]
 [0 0 0]]

Answer 1

Use NumPy's pad function:

import numpy as np
np.pad(r,(0,1))

This will pad with zeros r with padding size of 1 at the end of the rows and columns, and will not pad at the beginning (as we set to 0 the padding size there).

Answer 2

You simply can define a new nparray and map the old one to it:

x = np.array([[1, 2], [3, 4]])

reshaped_array = np.zeros((3, 3))
reshaped_array[:2, :2] = x

output:

array([[1., 2., 0.],
       [3., 4., 0.],
       [0., 0., 0.]])