Print matrix elements in diamond pattern using python

Question

I need to traverse and print the matrix elements in a diamond pattern.

matrix = [[ 1,  2,  3,  4,  5], 
          [ 6,  7,  8,  9, 10], 
          [11, 12, 13, 14, 15], 
          [16, 17, 18, 19, 20], 
          [21, 22, 23, 24, 25]]

Output: [13, 8, 14, 18, 12, 3, 9, 15, 19, 23, 17, 11, 7, 4, 10, 20, 24, 22, 16, 6, 2, 5, 25, 21, 1]

Answer 1

# Create a program to print in diamond pattern
import math;
matrix = [[ 1,  2,  3,  4,  5], 
          [ 6,  7,  8,  9, 10], 
          [11, 12, 13, 14, 15], 
          [16, 17, 18, 19, 20], 
          [21, 22, 23, 24, 25]]

def printDiamond(matrix):
    round = 0
    # Start with the row and col in the center of the matrix
    row = math.floor(len(matrix) / 2)
    col = math.floor(len(matrix[0]) /2)
    new_list = []

    # Subtract number of rows as number of rounds
    # Add one col and add one row - repeat until reaching the center row
    # Subtract one col and add one row - repeat until reaching the center column
    # Subtract one col and subtract one row - repeat until reaching the center row
    # Subtract one row and add one col - repeat until reaching the center column
    movements = {'down_right':[1,1],'down_left':[1,-1],'up_left':[-1,-1],'up_right':[-1,1]}
    directions = [movements['down_right'],movements['down_left'],movements['up_left'],movements['up_right']]
    
    for round in range(len(matrix)):
        # Go upwards first
        new_row = row - round
        new_col = col
        try:
            if new_row >= 0:
                # Make sure that the indices are 0 or positive
                #print(matrix[new_row][col])
                new_list.append(matrix[new_row][col])
        except IndexError:
            # By subtracting round from row to make new row
            # Negative indices will exist
            pass
        for direction in directions:
            # Move in the correct direction 
            # And repeat the number of times equal to the current round
            for pos in range(round):
                new_row += direction[0]
                new_col += direction[1]
                try:
                    if (new_row >= 0 and new_col >= 0):
                        if (matrix[new_row][new_col] not in new_list):
                            new_list.append(matrix[new_row][new_col])
                            # print(matrix[new_row][new_col])
                    
                except IndexError:
                    pass
    return new_list

new_list = printDiamond(matrix)
print(new_list)