[python] What's the function like sum() but for multiplication? product()?

Python's sum() function returns the sum of numbers in an iterable.

sum([3,4,5]) == 3 + 4 + 5 == 12

I'm looking for the function that returns the product instead.

somelib.somefunc([3,4,5]) == 3 * 4 * 5 == 60

I'm pretty sure such a function exists, but I can't find it.

Numeric.product 

( or

reduce(lambda x,y:x*y,[3,4,5])

)

Use this

def prod(iterable):
    p = 1
    for n in iterable:
        p *= n
    return p

Since there's no built-in prod function.

There's a prod() in numpy that does what you're asking for.

There isn't one built in, but it's simple to roll your own, as demonstrated here:

import operator
def prod(factors):
    return reduce(operator.mul, factors, 1)

See answers to this question:

Which Python module is suitable for data manipulation in a list?

Perhaps not a "builtin", but I consider it builtin. anyways just use numpy

import numpy 
prod_sum = numpy.prod(some_list)

I prefer the answers a and b above using functools.reduce() and the answer using numpy.prod(), but here is yet another solution using itertools.accumulate():

import itertools
import operator
prod = list(itertools.accumulate((3, 4, 5), operator.mul))[-1]

Actually, Guido vetoed the idea: http://bugs.python.org/issue1093

But, as noted in that issue, you can make one pretty easily:

from functools import reduce # Valid in Python 2.6+, required in Python 3
import operator

reduce(operator.mul, (3, 4, 5), 1)