Understand the basic conception of the Numpy which is very important in opencv.

numpy mofan tutorial

numpy speed fast speed cuz base on C lan

numpy base on matrix, matrix is quicker and list and dict

basic properties of np

matrix

cvt a 2D array to np.array

import numpy as np
array = np.array(
    [
      [1,2,3], # a row
      [2,3,4]
    ]
)

print(array.shape)
print(array.size)

numpy class 3

dtype

dtype float int

a = np.arange(10,20,2)