Count occurrences of integers in moving window on 2-dimensional numpy array

Question

I would like to calculate per integer how often this value occurs within a moving window. I have no idea however how to tackle this as I can only find how to calculate a focal mean.

So the window has the size:

kernel =array([[1, 1, 1],
               [1, 1, 1],
               [1, 1, 1]])

The input data:

input = array([[3, 3, 2, 3],
               [3, 1, 2, 3],
               [2, 1, 1, 1],
               [3, 1, 3, 2]])

The output should look like the following: First "layer" count of 1, Second "layer" count of 2 etc.

output = array([[[1, 1, 1, 0],
                 [2, 3, 4, 2],
                 [3, 4, 5, 3],
                 [2, 3, 4, 2]],
                [[0, 2, 2, 0],
                 [1, 3, 2, 2],
                 [1, 2, 2, 2],
                 [1, 1, 1, 1]],
                [[3, 3, 3, 2],
                 [3, 3, 3, 2],
                 [2, 3, 2, 2],
                 [1, 2, 1, 1]]])

The output should be a 3 dimensional array. x, y the dimensions of the original array, and z the amount of unique integers. Each layer shows the count per unique integer.

if you have any directions on how to solve this that would be great.

Answer 1

import numpy as np

def focal_lcz_count(image, window_w, window_h, int_val):

    w, h = image.shape
    count_arr = np.zeros([w, h])
    for i in range(w):
        for j in range(h):
            window = image[i:i+window_w, j:j+window_h]
            np.zeros([w, h])
            count_arr[i,j] = np.count_nonzero(window == int_val)

    return count_arr


def list_focal_count(input_array,integer_list, window_size):

    count_list = []
    for i, item in enumerate(integer_list):
        count_out = focal_lcz_count(image=input_array, window_w=window_size, window_h=window_size, int_val=item)
        count_out = count_out.flatten()
        count_list.append(count_out)
        raster_array = np.asarray(count_list)

    return count_list


input = np.random.randint(1, 4, ( 8, 8))
integ_list= [1,2,3]

result = list_focal_count(input_array=input,integer_list=integ_list, window_size=3)
print(result)