What's the simplest way to extend a numpy array in 2 dimensions?

Question

I have a 2d array that looks like this:

XX
xx

What\'s the most efficient way to add an extra row and column:

xxy
xxy
yyy
         


        

Answer 1

I find it much easier to "extend" via assigning in a bigger matrix. E.g.

import numpy as np
p = np.array([[1,2], [3,4]])
g = np.array(range(20))
g.shape = (4,5)
g[0:2, 0:2] = p

Here are the arrays:

p

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

g:

array([[ 0,  1,  2,  3,  4],
       [ 5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14],
       [15, 16, 17, 18, 19]])

and the resulting g after assignment:

   array([[ 1,  2,  2,  3,  4],
       [ 3,  4,  7,  8,  9],
       [10, 11, 12, 13, 14],
       [15, 16, 17, 18, 19]])