NumPy – numpy.vstack() – Stack Arrays Vertically
To vertically stack two or more numpy arrays, you can use vstack() function.
vstack() takes tuple of arrays as argument, and returns a single ndarray that is a vertical stack of the arrays in the tuple.
Examples
1. Vertically stack 2D numpy arrays
In this example, we shall take two 2D arrays of size 2×2 and shall vertically stack them using vstack() method.
Python Program
import numpy as np
#initialize arrays
A = np.array([[2, 1], [5, 4]])
B = np.array([[3, 4], [7, 8]])
#vertically stack arrays
output = np.vstack((A, B))
print(output)Output
[[2 1]
[5 4]
[3 4]
[7 8]]2. Vertically stack 1D numpy arrays
In this example, we shall take three arrays and stack them vertically.
Python Program
import numpy as np
#initialize arrays
A = np.array([2, 1, 5, 4])
B = np.array([3, 4, 7, 8])
C = np.array([8, 6, 0, 3])
#vertically stack arrays
output = np.vstack((A, B, C))
print(output)Output
[[2 1 5 4]
[3 4 7 8]
[8 6 0 3]]Summary
In this NumPy Tutorial, we learned how to stack numpy arrays vertically using vstack() function, with the help of well detailed example programs.