Optimized method for calculating cosine distance in Python

Question

I wrote a method to calculate the cosine distance between two arrays:

def cosine_distance(a, b):
    if len(a) != len(b):
        return False
    numerator = 0
         


        

Answer 1

No need to take abs() of a[i] and b[i] if you're squaring it.

Store a[i] and b[i] in temporary variables, to avoid doing the indexing more than once. Maybe the compiler can optimize this, but maybe not.

Check into the **2 operator. Is it simplifying it into a multiply, or is it using a general power function (log - multiply by 2 - antilog).

Don't do sqrt twice (though the cost of that is small). Do sqrt(denoma * denomb).