How to combine dimensions in numpy array?

Question

I'm using OpenCV to read images into numpy.array, and they have the following shape.

import cv2

def readImages(path):
    imgs = []
    for file in os.listdir(path):
        if file.endswith('.png'):
            img = cv2.imread(file)
            imgs.append(img)
    imgs = numpy.array(imgs)
    return (imgs)

imgs = readImages(...)
print imgs.shape  # (100, 718, 686, 3)

Each of the image has 718x686 pixels/dimension. There are 100 images.

I don't want to work on 718x686, I'd like to combine the pixels into a single dimension. That is, the shape should look like: (100,492548,3). Is there anyway either in OpenCV (or any other library) or Numpy that allows me to do that?

Answer 1

Without modifying your reading function:

imgs = readImages(...)
print imgs.shape  # (100, 718, 686, 3)

# flatten axes -2 and -3, using -1 to autocalculate the size
pixel_lists = imgs.reshape(imgs.shape[:-3] + (-1, 3))
print pixel_lists.shape  # (100, 492548, 3)