Selecting A Random List Element Of Length N In Python

I know you can use random.choice to choose a random element from a list, but I am trying to choose random elements of length 3. For example, list1=[a,b,c,d,e,f,g,h] I want the ou

Solution 1:

You want a sample; use random.sample() to pick a list of 3 elements:

random.sample(list1, 3)

Demo:

>>> import random
>>> list1 = ['a', 'b', 'c' ,'d' ,'e' ,'f', 'g', 'h']
>>> random.sample(list1, 3)
['e', 'b', 'a']

If you needed a sublist, then you are stuck with picking a random start index between 0 and the length minus 3:

def random_sublist(lst, length):
    start = random.randint(len(lst) - length)
    return lst[start:start + length]

which works like this:

>>>defrandom_sublist(lst, length):...    start = random.randint(len(lst) - length)...return lst[start:start + length]...>>>random_sublist(list1, 3)
['d', 'e', 'f']

Solution 2:

idx = random.randint(0, len(list1)-3)
list1[idx:idx+3]

Solution 3:

If you want the result to wrap around to the start of the list you can do:

idx = randint(0, len(list1))
(list1[idx:] + list1[:idx])[:3]

Solution 4:

If all you want is a random subset of the original list, you can use

import randomrandom.sample(your_list, sample_size)

However, if you want your sublists to be contiguous (like the example you've given), you might be better off picking two random indices and slicing the list accordingly:

a = random.randint(0, len(your_list) - sample_length)
sublist = your_list[a:b+sample_length]