size of NumPy array

Is there an equivalent to the MATLAB

 size()

command in Numpy?

In MATLAB,

>>> a = zeros(2,5) 0 0 0 0 0 0 0 0 0 0
>>> size(a) 2 5

In Python,

>>> a = zeros((2,5))
>>>
array([[ 0., 0., 0., 0., 0.], [ 0., 0., 0., 0., 0.]])
>>> ?????

3 Answers

This is called the "shape" in NumPy, and can be requested via the .shape attribute:

>>> a = zeros((2, 5))
>>> a.shape
(2, 5)

If you prefer a function, you could also use numpy.shape(a).

Yes numpy has a size function, and shape and size are not quite the same.

Input

import numpy as np
data = [[1, 2, 3, 4], [5, 6, 7, 8]]
arrData = np.array(data)
print(data)
print(arrData.size)
print(arrData.shape)

Output

[[1, 2, 3, 4], [5, 6, 7, 8]]
8 # size
(2, 4) # shape

[w,k] = a.shape will give you access to individual sizes if you want to use it for loops like in matlab