No repeats in a for loop with random.sample

Question

I have the following:

list1 = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k"]

for i in range(3):
        print(random.sample(list1, k=1))
        print(random.sample(list1, k=1))
        print(random.sample(list1, k=1))

and am looking for something like:

['a', 'g', 'i']
['c', 'h', 'b']
['k', 'd', 'e']

The idea being to have no repeats anywhere.

I understand that I could slice the list if not using a loop, but am unsure of how to go about it with the loop involved.

A.J. Uppal · Accepted Answer · 2019-12-28T21:50:16.773

5

Just shuffle it and take subsequent slices:

list1 = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k"]
random.shuffle(list1)

N = 3

for i in range(0, len(list1)-N+1, N):
    print(list1[i:i+N])

#['c', 'b', 'd']
#['i', 'e', 'j']
#['h', 'g', 'f']

edited Dec 28 '19 at 21:50

answered Dec 28 '19 at 04:39

A.J. Uppal

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That works perfectly. If the number of strings within the list changes, is there a way to automatically adjust the range() to accommodate that? – Dean Arvin Dec 28 '19 at 16:27
1

Yep, check edit. – A.J. Uppal Dec 28 '19 at 21:44

score 4 · Answer 2 · answered Dec 28 '19 at 04:39

4

Shuffle the list then break it apart:

import random

list1 = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k"]
random.shuffle(list1)
for i in range(0, len(list1), 3):
    print(list1[i:i+3])

answered Dec 28 '19 at 04:39

Anonymous

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Holy s*** we put the exact same thing :) +1 for alacrity – A.J. Uppal Dec 28 '19 at 04:40
@A.J.Uppal And the same for you :) It's the best way to do it – Anonymous Dec 28 '19 at 04:42

score 1 · Answer 3 · answered Dec 28 '19 at 04:42

1

You could also use you're original sample function and slice the list using list comprehensions:

list1 = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k"]

output = random.sample(list1, k=9)
output = [output[i:i+3] for i in range(0,9,3)]

answered Dec 28 '19 at 04:42

Jay Mody

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score 1 · Answer 4 · answered Dec 28 '19 at 04:55

1

Input:

import random
list1 = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k"]

for i in range(3):
  print([list1.pop(random.choice(range(len(list1)))) for i in range(3)])

Output:

['j', 'g', 'b']
['f', 'c', 'h']
['e', 'k', 'i']

answered Dec 28 '19 at 04:55

Petar Luketina

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score 1 · Answer 5 · answered Dec 28 '19 at 05:04

1

>>> list1 = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k"]
>>> mylist = random.sample(list1, k=9)
>>> print([mylist[i:i+3] for i in range(0, 9, 3)])

output [['e', 'b', 'i'], ['k', 'h', 'd'], ['j', 'f', 'a']]

answered Dec 28 '19 at 05:04

Salim

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This answer is same as Jay's. While I posted this I didn't see Jay's answer as I was busy finding my own answer. – Salim Dec 28 '19 at 05:19

No repeats in a for loop with random.sample

5 Answers5