Scramble Python List

Question

Before I ask my question, let me get this straight...

This is not a duplicate of Does anyone know a way to scramble the elements in a list? and Shuffle an array with python, randomize array item order with python. I'll explain why...

I want to know how to scramble an array, and make a new copy. Because random.shuffle() modifies the list in place (and returns None), I want to know if there is another way to do this so I can do scrambled=scramblearray(). If there isn't a built-in function, I could define a function to do this if possible.

possible duplicate of [Shuffle an array with python](http://stackoverflow.com/questions/473973/shuffle-an-array-with-python) — Marcin, Mar 19 '12 at 13:04
@Marcin Personally, I don't think that these answers could be merged with the answers on [Shuffle an array with Python](http://stackoverflow.com/questions/473973/shuffle-an-array-with-python) — CoffeeRain, Mar 19 '12 at 13:17
Yes, they could. They happen to also demonstrate that you can copy an array. There is no reason why you couldn't have figured this out by yourself. — Marcin, Mar 19 '12 at 13:18
I think you should possible make a new copy of the array and scramble it using `random.shuffle()`. It works fine. If you don't like that way, you should probably explain clearly why you don't want. That will help us to understand. — Surya, Mar 19 '12 at 13:19

score 24 · Accepted Answer · answered Mar 19 '12 at 13:02

24

def scrambled(orig):
    dest = orig[:]
    random.shuffle(dest)
    return dest

and usage:

import random
a = range(10)
b = scrambled(a)
print a, b

output:

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9] [6, 0, 2, 3, 1, 7, 8, 5, 4, 9]

answered Mar 19 '12 at 13:02

eumiro

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koffein · Answer 2 · 2013-11-07T17:21:25.413

11

Use sorted(). It returns a new list and if you use a random number as key, it will be scrambled.

import random
a = range(10)
b = sorted(a, key = lambda x: random.random() )
print a, b

Output:

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9] [5, 9, 0, 8, 7, 2, 6, 4, 1, 3]

edited Nov 07 '13 at 17:21

answered Nov 07 '13 at 12:30

koffein

1,792
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Marcin · Answer 3 · 2012-03-19T13:10:43.187

3

Copy the array then scramble it:

import random

array = range(10)   
newarr = array[:] # shallow copy should be fine for this
random.shuffle(newarr)
#return newarr if needs be.
zip(array, newarr) # just to show they're different

Out[163]:
[(0, 4),
 (1, 8),
 (2, 2),
 (3, 5),
 (4, 1),
 (5, 6),
 (6, 0),
 (7, 3),
 (8, 7),
 (9, 9)]

edited Mar 19 '12 at 13:10

answered Mar 19 '12 at 13:03

Marcin

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Scramble Python List

3 Answers3