Python Program to find the Next Nearest element in a Matrix

Given a matrix, a set of coordinates and an element, the task is to write a python program that can get the coordinates of the elements next occurrence.

Input : test_list = [[4, 3, 1, 2, 3], [7, 5, 3, 6, 3], [8, 5, 3, 5, 3], [1, 2, 3, 4, 6]], i, j = 1, 3, K = 3

Output : (1, 4)

Explanation : After (1, 3), 3 is found at (1, 4)

Input : test_list = [[4, 3, 1, 2, 3], [7, 5, 3, 6, 3], [8, 5, 3, 5, 3], [1, 2, 3, 4, 6]], i, j = 2, 3, K = 3

Output : (2, 4)

Explanation : After (2, 3), 3 is found at (2, 4)

Method : Using loop and enumerate()

In this we start iteration from the required coordinates and check just for the next nearest K inside the rectangle formed from row + 1, col + 1 to N, N coordinate. Returns -1, -1 if not occurrence is found.

Example:

Python3

# get Nearest coord.
def near_coord(test_list, x, y, val):
    for idx, row in enumerate(test_list[x:]):
        for j, ele in enumerate(row):

            # checking for value at lower formed rectangle
            if ele == val and j > y:
                return idx + x, j

    # if no index found
    return -1, -1


# initializing list
test_list = [[4, 3, 1, 2, 3], [7, 5, 3, 6, 3],
             [8, 5, 3, 5, 3], [1, 2, 3, 4, 6]]

# printing original list
print("The original list is : " + str(test_list))

# initializing check coord
i, j = 1, 3

# initializing K
K = 3

# getting nearest coordinates
res_abs, res_ord = near_coord(test_list, i, j, K)

# printing result
print("Found K index : " + str((res_abs, res_ord)))

Output:

The original list is : [[4, 3, 1, 2, 3], [7, 5, 3, 6, 3], [8, 5, 3, 5, 3], [1, 2, 3, 4, 6]]

Found K index : (1, 4)

Time Complexity: O(n*m)
Auxiliary Space: O(k)