What's the Python function like sum() but for multiplication?

Question

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.

Answer 1

Numeric.product

( or

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

)

Answer 2

Use this

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

Since there's no built-in prod function.

Answer 3

If Python had one it would be called product(), unfortunately it doesn't. You can do something like Steve B. mentioned.

Answer 4

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

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

See answers to this question:

http://stackoverflow.com/questions/493853/which-python-module-is-suitable-for-data-manipulation-in-a-list

Answer 5

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

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

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