CODEWITHSUNDEEP
pythonarraysshuffle
Dominik Smolinský
Dominik Smolinský

Reputation: 71

random.shuffle only works once

My task is to shuffle numbers and that append to array. My program is shuffling it but only once.

order = []
population = []
i = 0
for i in range(i,M):
    order.append(i)
i = 0
for i in range(i,10):
    random.shuffle(order)
    population.append(order)

my input = [[1, 0, 2], [1, 0, 2], [1, 0, 2], [1, 0, 2], [1, 0, 2]]
expected input = [[0, 2, 1], [1, 0, 2], [0, 2, 1], [2, 0, 1], [2, 1, 0]]

Upvotes: 1

Views: 234

Answers (2)

Gamopo
Gamopo

Reputation: 1598

You have to use copy because you are appending the same reference over and over again, so you are actually shuffling order but it is affecting to every instance in population

import random
import copy

order = []
population = []

i = 0
for i in range(i,M):
    order.append(i)
i = 0
for i in range(i,10):
    random.shuffle(order)
    population.append(copy.deepcopy(order))

print(population)

Upvotes: 0

kederrac
kederrac

Reputation: 17322

you are appending references to the same list order so you have one list in the final result, you could use:

for i in range(i,10):
    new_o = order.copy()
    random.shuffle(new_o)
    population.append(new_o)

Upvotes: 1

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