Which way would be more "Pythonic" for this exercise?

Question

I have an assignment here:

Given an array of ints, return the number of 9's in the array.

array_count9([1, 2, 9]) → 1
array_count9([1, 9, 9]) → 2
array_count9([1, 9, 9, 3, 9]) → 3

I have 2 ideas for this, one is:

def array_count9(nums):
    count = 0
    list1 = [x for x in nums if x==9]
    return len(list1)

and the other:

def array_count9(nums):
    count = 0
    for n in nums:
        if n==9:
            count +=1
    return count

But I wonder which way would be more Pythonic, in terms of performance, clarity,... ? Thank you very much

Answer 1

The most Pythonic way would be to use a built-in function, count in this case. Try this:

def array_count9(nums):
  return nums.count(9)