How to reshape a (x, y) numpy array into a (x, y, 1) array?

How do you reshape from a (55, 11) numpy array to a (55, 11, 1) numpy array?

Attempts:

• Simply doing numpy_array.reshape(-1, 1) without any loop produces a flat array that is not 3D.
• The following for loop produces a "cannot
  broadcast error":

for i in range(len(numpy_array)):
       numpy_array[i] = numpy_array[i].reshape(-1, 1)

>Solution :

Maybe you are looking for numpy.expand_dims(https://numpy.org/doc/stable/reference/generated/numpy.expand_dims.html)?

import numpy
a = numpy.random.rand(55,11)
print(a.shape) # 55,11
print(numpy.expand_dims(a, 2).shape) # 55, 11, 1