playing with a matrix

Im trying to write a class that creates a matrix of zeros, then uses a random number generator to pick spots on the matrix. it changes the zero in that spot to a one, until the matrix is all ones. Can someone critique/correct my code? (I also want the generator to check its proximity on the matrix, and try 3 times to find a spot that is 2 spots away from any ones.)

import random
import numpy as np
#agents is amount of agents available to fill grid
class Gridmodel():
    def __init__(self, gridsize, agents):
        self.gridsize = gridsize
        self.agents = agents 
        self.gridmodel = np.zeros([self.gridsize, self.gridsize],dtype=int)


    def foundspot(self):
        foundspot = False         
        tries = 0
        while foundspot == False and tries <= 3:
            x = random.randint(0, self.gridsize)
            y = random.randint(0, self.gridsize)
            if self.gridmodel[x][y] < 0:
                foundspot = True
        else: 
            tries += 1

    def goodspot(self, x, y):
        goodspot = self.seats[x][y]
        for i in range(-1,2):
            for j in range(-1,2):

                print i, j, self.seats[i][j]