It has been a very long time since I've used Python. What I'm looking for: I would like to create a 6-by-6 random matrix where each component is either 1 or 2, so that there are 18 ones and 18 twos. Attempt:
import numpy import random array = numpy.zeros((6, 6)) while (array == 1).sum() != 18 or (array == 2).sum() != 18: for i in range(0, 6): for j in range(0, 6): array[i][j] = random.randint(1, 2) print array Sure, this works. But this seems to me to be extremely inefficient, as the code is literally having to insert new matrix values until the number of ones/twos is 18. How can I make this more efficient?
144k 22 22 gold badges 188 188 silver badges 472 472 bronze badges asked Sep 16, 2015 at 2:56 Clarinetist Clarinetist 311 1 1 silver badge 13 13 bronze badgesJust create a list of 18 ones and 18 twos, shuffle it, then reshape to 6x6:
from random import shuffle from numpy import reshape nums = [1]*18 + [2]*18 shuffle(nums) arr = reshape(nums, (6, 6)) Produces (for example):
array([[1, 2, 2, 1, 2, 1], [2, 2, 2, 2, 2, 1], [2, 2, 2, 1, 1, 2], [1, 1, 1, 1, 2, 2], [2, 1, 1, 2, 1, 1], [1, 2, 1, 1, 1, 2]])