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I have been asked to make a number matching game for a school project, which involves generating random numbers in a grid. I have managed to generate the grid full of random numbers, but I need them to be in pairs so that they can be matched. Any help would be greatly appreciated. Here is my code so far:

def play(): import random

sizeofgrid()

board = []

showboard = []

for row in range(gridsize):
    board.append([])
    for column in range(gridsize):
        board[row].append(random.randint(0, 9))

def print_board(board):
    for row in board:
        print(' '.join([str(i) for i in row]))

showboard = [['O' for _ in range(gridsize)] for _ in range(gridsize)]

print_board(showboard)
print_board(board)
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  • Do you want there to be only two of each number? Or, numbers 0-9 repeated as often as needed, but end in an even number of each? Commented Sep 7, 2017 at 16:27
  • Yes, I need two of each number which are arranged in random positions around the grid. Thinking about it, it can be from 0 to however many is required to fill the grid (the size of the grid is chosen by the user). I have obviously made sure that there can only be an even number of spaces in the grid. Commented Sep 7, 2017 at 16:36

2 Answers 2

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One approach might be to generate half of the numbers you need and then double that list. Then, shuffle the desired values and resize them into a grid.

from random import randint, shuffle

size = 4 # must be even
pairs = size**2/2

pool = range(pairs) * 2
# [0, 1, 2, 3, 4, 5, 6, 7, 
#  0, 1, 2, 3, 4, 5, 6, 7]

shuffle(pool)

grid = [pool[i:i+size] for i in range(0, size**2, size)]
# [[4, 5, 0, 7], [1, 7, 3, 5], [2, 1, 2, 6], [4, 0, 3, 6]]
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1 Comment

Thanks for the help, I will give it a go.
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You need to change your approach. You can try one of two things:

  1. Start with an empty board. Generate a random number, then generate two random locations on the board. Keep re-generating until you find an empty slot, twice. Put the random number into both locations.

    for _ in range(width * height // 2):
    number = pick_random_number()
    loc1 = find_random_empty_spot()
    board[loc1.row][loc1.col] = number
    loc2 = find_random_empty_spot()
    board[loc2.row][loc2.col] = number

  2. Compute how many locations will need to be filled. Generate a N/2 random numbers, put each random number into a list, twice. Now, shuffle the list, and then loop over the board, inserting items from the list into the board.

    num_picks = width * height // 2
picks = []

for _ in range(num_picks):
    number = pick_random_number()
    picks.extend([number, number])

random.shuffle(picks)

for row in range(height):
    for col in range(width):
        board[row][col] = picks.pop()

Either of these approaches will get you the paired behavior you want. Which one you choose is a matter of comfort.

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3 Comments

Thanks for the help, how would I go about generating a random position? Would I use coordinates?
That's one way. Generate a random int in the range(width) and another in range(height).
Thanks for your help.

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