I have a 2 dimensional array : A = numpy.array([[1, 2, 3], [4, 5, 6]]) and would like to convert it to a 3 dimensional array : B = numpy.array([[[1, 2, 3], [4, 5, 6]]])
Is there a simple way to do that ?
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2 Answers
Simply add a new axis at the start with np.newaxis -
import numpy as np
B = A[np.newaxis,:,:]
We could skip listing the trailing axes -
B = A[np.newaxis]
Also, bring in the alias None to replace np.newaxis for a more compact solution -
B = A[None]
Comments
It is also possible to create a new NumPy array by using the constructor so that it takes in a list. This list contains a single element which is the array A and it will allow you to create same array with the singleton dimension being the first one. The result would be the 3D array you desire:
B = numpy.array([A])
Example Output
In [13]: import numpy as np
In [14]: A = np.array([[1, 2, 3], [4, 5, 6]])
In [15]: B = np.array([A])
In [16]: B
Out[16]:
array([[[1, 2, 3],
[4, 5, 6]]])