Rotate Python Numpy NDArray

# Interactive mode
python

>>> import numpy as n

# Create an array
>>> np.array([0, 1, 2])
array([0, 1, 2])

# An array of 2x3
>>> tmp = np.array([[0, 1, 2], [3, 4, 5]])

>>> tmp
array([[0, 1, 2],
       [3, 4, 5]])

# Rotate ndarray 90 degrees in the counterclockwise direction
>>> np.rot90(tmp)
array([[2, 5],
       [1, 4],
       [0, 3]])

# Option k: number of rotations (90 * k)
>>> np.rot90(tmp, k=2)
array([[5, 4, 3],
       [2, 1, 0]])

# Interactive mode
python

>>> import cv2

>>> img = cv2.imread('path_to_image.jpg')

# Rotate image (ndarray) 90 degrees in the clockwise direction
#   - cv2.ROTATE_90_CLOCKWISE
#   - cv2.ROTATE_90_COUNTERCLOCKWISE
#   - cv2.ROTATE_180
>>> cv2.rotate(img, cv2.ROTATE_90_CLOCKWISE)