random.choices with weighted options output

Question

import random
a = 1
b = 2
c = 3

print(random.choices([a,b,c], [50,3,1]))

The code above outputs [1], [2] or [3] can someone explain why the output has

Answer 1

random.choices draws a list of values that you can specify with k=.. when calling it:

fourty = random.choices(range(10),k=40)

You can print the single value you get by indexing into it using choices method of specifying probabilities

print(random.choices([a,b,c], [50,3,1])) [0]  # get the one single value from the result list

or you can use random.choice() providing an iterable that reflects your propabilites:

import random
a=1
b=2
c=3

# create an iterable that reflects your propabilies and draw 1 element from it
print(random.choice(  [a]*50+[b]*3+[c] ) )  

Answer 2

Because random.choices(population, weights=None, *, cum_weights=None, k=1) returns a list of k elements. In your case, since you didn't pass any value for k, the list has only an item.

If you want to get a value, and not a list, you could use random.choice(seq), but in that case you could not pass a list of weights as with random.choices().