如何将 3d 数组展平为 1d 数组

Question

I need a 3d nested array. How can I flatten that to a 1d array? (Because of performance) I assume, that I need to multiply some stuff etc. but I'm not the greatest mathematician. Thanks!

def imgRGB(im):
    width, height = im.size

    #create matrix
    matrix = []
    for i in range(height):
        matrix.append([[0,0,0] for _ in range(width)])

    #get the rgb values
    for x in range(width):
        for y in range(height):
            r,g,b = im.getpixel((x,y))
            matrix[y][x][0] = r
            matrix[y][x][1] = g
            matrix[y][x][2] = b
    return matrix

The pixel values will be compared to other RGB values to find the closest match.

def getNearestColor(rgb):
    a = []
    for i in range(len(rgbValues)):
        d = ((rgbValues[i][0]-rgb[0])*0.3)**2 + ((rgbValues[i][1]-rgb[1])*0.59)**2 + ((rgbValues[i][2]-rgb[2])*0.11)**2
        a.append(d)
    list.sort(a)
    return a[0]

Answer 1

You can use the ndarray.flatten, in your example it would be matrix.flatten() . This returns the flattened version of your matrix. Documentation here also has an example.

Answer 2

If I understand it correctly, you want to do the following:

rgbValues = np.array(im).reshape(-1,3)
a = np.sort(np.sum(((rgbValues - rgb)* [0.3, 0.59, 0.11])**2, axis=1))

where rgb is a list [r, g, b] for some values r, g, b.