mean(iterable)

gistfile1.txt

def mean(iterable):
    """Find the mean value of the sequence (0 if empty). Consumes generators"""
    if hasattr(iterable, '__len__'):
        n = len(iterable)
        return sum(iterable) / float(n) if n > 0 else 0.0
    else:
        sentinel, iterable = object(), iter(iterable)
        n, s = 1, next(iterable, sentinel)
        if s is sentinel: return 0.0
        for x in iterable: n,s = n+1, s+x
        return s / float(n)

def nanmean(iterable):
    """Find the mean but skip nan's, and return nan if there are no numbers"""
    from itertools import chain
    gen = (x for x in iterable if x == x)
    try:
        fst = next(gen)
        return mean(chain([fst], gen))
    except StopIteration: return float('nan')