What is the role of keepdims in Numpy (Python)?

Question

When I use np.sum, I encountered a parameter called keepdims. After looking up the docs, I still cannot understand the meaning of keepdims

Answer 1

You can keep the dimension with "keepdims=True" if you sum a matrix For example:

import numpy as np
x  = np.array([[1,2,3],[4,5,6]])
x.shape
# (2, 3)

np.sum(x, keepdims=True).shape
# (1, 1)
np.sum(x, keepdims=True)
# array([[21]]) <---the reault is still a 1x1 array

np.sum(x, keepdims=False).shape
# ()
np.sum(x, keepdims=False)
# 21 <--- the result is an integer with no dimesion