CODEWITHSUNDEEP
pythonlistpython-2.7random
tktk
tktk

Reputation: 11754

Random division of list to two complementary sublists

I have a list which I want to randomly divide into two sublists of known size, which are complements of one another. e.g., I have [1,5,6,8,9] and I want to divide it to [1,5,9] and [6,8]. I care less about efficiency and just want it to work. Order does not matter.

I started with:

pop = [...] #some input
samp1 = random.sample(pop, samp1len)
samp2 = [x for x in pop if x not in samp1]

However, this solution fails with repetitive items. If pop = [0,0,0,3,5], and the first selection of length 3 was [0,3,5], I would still like samp2 to be [0,0], which my code currently fails to provide.

Is there some built in option in random that I missed? Can anyone offer a simple solution?

Upvotes: 4

Views: 550

Answers (1)

Ashwini Chaudhary
Ashwini Chaudhary

Reputation: 251186

How about something like this?

Generate a list of indices and shuffle them:

>>> indices = range(len(pop))
>>> random.shuffle(indices)

Then slice the indices list and use operator.itemegetter to get the items:

>>> from operator import itemgetter
>>> itemgetter(*indices[:3])(pop)
(0, 0, 3)
>>> itemgetter(*indices[3:])(pop)
(5, 0)

Upvotes: 4

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