Syntax: np.vstack((a, b, ...)) Example: import numpy as np a = np.array([1, 2, 3]) b = np.array([4, 5, 6]) stacked = np.vstack((a, b)) [[1 2 3] [4 5 6]] import numpy as np x = np.array([7, 8, 9]) y = np.array([10, 11, 12]) result = np.vstack((x, y)) print(result) [[ 7 8 9] [10 11 12]]