compute mean in python for a generator
- by nmaxwell
Hi,
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 mean, so I don't need to store the numbers.
The problem is that numpy.mean breaks if you pass it a generator. I can write a simple function to do what I want, but I'm wondering if there's a proper, built-in way to do this?
It would be nice if I could say "sum(values)/len(values)", but len doesn't work for genetators, and sum already consumed values.
here's an example:
import numpy
def my_mean(values):
n = 0
Sum = 0.0
try:
while True:
Sum += next(values)
n += 1
except StopIteration: pass
return float(Sum)/n
X = [k for k in range(1,7)]
Y = (k for k in range(1,7))
print numpy.mean(X)
print my_mean(Y)
these both give the same, correct, answer, buy my_mean doesn't work for lists, and numpy.mean doesn't work for generators.
I really like the idea of working with generators, but details like this seem to spoil things.
thanks for any help
-nick
