On Thu, Nov 3, 2016 at 7:29 PM, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: >> lst = map (lambda x: x*5, lst) >> lst = filter (lambda x: x%3 == 1, lst) >> And perform especially bad in CPython compared to a comprehension. > > I doubt that. >
It's entirely possible. A list comp involves one function call (zero in Py2), but map/lambda involves a function call per element in the list. Function calls have overhead. Arthur, I would suggest looking at what numpy and pandas do. When you're working with ridiculously large data sets, they absolutely shine; and if you're not working with that much data, the performance of map or a list comp is unlikely to be significant. If the numpy folks have a problem that can't be solved without new syntax, then a proposal can be brought to the core (like matmul, which was approved and implemented). ChrisA -- https://mail.python.org/mailman/listinfo/python-list
