[Python-Dev] sum(...) limitation (original) (raw)

Paul Moore p.f.moore at gmail.com
Sat Aug 9 10:36:31 CEST 2014

On 9 August 2014 06:08, Steven D'Aprano <steve at pearwood.info> wrote:

py> with Stopwatch(): ... sum(carray) # carray is a numpy array of 75000000 floats. ... 112500000.0 time taken: 52.659770 seconds py> with Stopwatch(): ... numpy.sum(carray) ... 112500000.0 time taken: 0.161263 seconds

Why have builtin sum at all if its use comes with so many caveats? Because sum() is a perfectly reasonable general purpose tool for adding up small amounts of numbers where high floating point precision is not required. It has been included as a built-in because Python comes with "batteries included", and a basic function for adding up a few numbers is an obvious, simple battery. But serious programmers should be comfortable with the idea that you use the right tool for the right job.

Changing the subject a little, but the Stopwatch function you used up there is "an obvious, simple battery" for timing a chunk of code at the interactive prompt. I'm amazed there's nothing like it in the timeit module...

Paul

More information about the Python-Dev mailing list