List comprehension for running total

Question

I want to get a running total from a list of numbers.

For demo purposes, I start with a sequential list of numbers using range

a = range         


        

Answer 1

Use itertools.accumulate(). Here is an example:

from itertools import accumulate

a = range(20)
runningTotals = list(accumulate(a))

for i in zip(a, runningTotals):
    print "{0:>3}{1:>5}".format(*i)

This only works on Python 3. On Python 2 you can use the backport in the more-itertools package.