random_matrix.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import pprint
import random
import string


def generate_matrix(i_length, j_length, default_value=None):

    return [[default_value] * j_length for _ in range(i_length)]


def get_matrix_index(matrix):
    # considering a simple 2D matrix.
    return [(i, j) for i in range(len(matrix)) for j in range(len(matrix[0]))]


def get_empty_position(matrix, get_all=False):

    all_empty_positions = [
        pos for pos in get_matrix_index(matrix) if not matrix[pos[0]][pos[1]]
    ]

    return random.choice(all_empty_positions) if not get_all else all_empty_positions  # noqa


def get_a_brand_new_character(text):

    return random.choice(list(
        set(string.ascii_lowercase + string.digits) | set(text)
    ))


def insert_text_randomly(matrix, text):

    for letter in text:

        position = get_empty_position(matrix)
        matrix[position[0]][position[1]] = letter

    for pos in get_empty_position(matrix, get_all=True):
        if not matrix[pos[0]][pos[1]]:

            matrix[pos[0]][pos[1]] = get_a_brand_new_character(text)

    return matrix


if __name__ == '__main__':

    matrix = generate_matrix(8, 8)
    text = list(set(input('Text: ')))

    pprint.pprint(insert_text_randomly(matrix, text))