Simple Weighted Average with Python

While I suspect there must already be a built in weighted average tool in some python library ( scipy / numpy), for a project I'm working on I just wrote my own.  I would love to hear what people think and if I can improve the function in any way.

def weightedAverage(valueWeightList):
        Takes a list of tuples (value, weight) and
        returns weighted average as calculated by
        Sum of all values * weights / Sum of all weights
        numerator = sum([v * w for v,w in valueWeightList])
        denominator = sum([w for v,w in valueWeightList])
        if(denominator != 0):
            return(float(numerator) / float(denominator))
            return None


  1. Nice and simple, although you don't need the list comprehension square brackets any more (unless you need to support older versions of Python). Thanks!

  2. Hey no problem. Unfortunately I'm still stuck in the 2.x Python world :(