Harmonic mean in a python function?

Question

I have 2 functions that give out precision and recall scores, I need to make a harmonic mean function defined in the same library that uses these two scores. The functions looks

Answer 1

The following will work with any number of arguments:

def hmean(*args):
    return len(args) / sum(1. / val for val in args)

To compute the harmonic mean of precision and recall, use:

result = hmean(precision, recall)

There are two problems with your function:

1. It fails to return a value.
2. On some versions of Python, it would use integer division for integer arguments, truncating the result.