How to use the np.vstack function in Python?

The np.vstack function is used to vertically stack arrays. It stacks the input arrays together along the vertical direction, returning a new array.

Here is how to use it:

import numpy as np

# 创建两个数组
arr1 = np.array([[1, 2, 3],
                 [4, 5, 6]])

arr2 = np.array([[7, 8, 9],
                 [10, 11, 12]])

# 使用np.vstack函数垂直堆叠这两个数组
result = np.vstack((arr1, arr2))

print(result)

The result of the operation is:

[[ 1  2  3]
 [ 4  5  6]
 [ 7  8  9]
 [10 11 12]]