compute mean in python for a generator

Question

I\'m doing some statistics work, I have a (large) collection of random numbers to compute the mean of, I\'d like to work with generators, because I just need to compute the

Answer 1

def my_mean(values):
    total = 0
    for n, v in enumerate(values, 1):
        total += v
    return total / n

print my_mean(X)
print my_mean(Y)

There is statistics.mean() in Python 3.4 but it calls list() on the input:

def mean(data):
    if iter(data) is data:
        data = list(data)
    n = len(data)
    if n < 1:
        raise StatisticsError('mean requires at least one data point')
    return _sum(data)/n

where _sum() returns an accurate sum (math.fsum()-like function that in addition to float also supports Fraction, Decimal).