According to documentation:
random.sample(population, k)
Return a k length list of unique elements chosen from the population sequence. Used for random sampling without replacement.
Basically, it picks k unique random elements, a sample, from a sequence:
>>> import random
>>> c = list(range(0, 15))
>>> c
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]
>>> random.sample(c, 5)
[9, 2, 3, 14, 11]
random.sample works also directly from a range:
>>> c = range(0, 15)
>>> c
range(0, 15)
>>> random.sample(c, 5)
[12, 3, 6, 14, 10]
In addition to sequences, random.sample works with sets too:
>>> c = {1, 2, 4}
>>> random.sample(c, 2)
[4, 1]
However, random.sample doesn't work with arbitrary iterators:
>>> c = [1, 3]
>>> random.sample(iter(c), 5)
TypeError: Population must be a sequence or set. For dicts, use list(d).