Gah. I'm sorry. I can't reproduce my original results! I don't know why, but the same tests I ran two days ago are not giving me the same timing. I need to go back to the drawing board here.
On Wednesday, June 17, 2015 at 11:37:52 AM UTC-5, Josh Langsfeld wrote: > > For me, map is 100x slower: > > julia> function f1(g,a) > [Pair(x,g) for x in a] > end > f1 (generic function with 1 method) > > > julia> function f2(g,a) > map(x->Pair(x,g), a) > end > f2 (generic function with 1 method) > > > julia> @time f1(2,ones(1_000_000)); > 25.158 milliseconds (28491 allocations: 24736 KB, 12.69% gc time) > > > julia> @time f1(2,ones(1_000_000)); > 6.866 milliseconds (8 allocations: 23438 KB, 37.10% gc time) > > > julia> @time f1(2,ones(1_000_000)); > 6.126 milliseconds (8 allocations: 23438 KB, 25.99% gc time) > > > julia> @time f2(2,ones(1_000_000)); > 684.994 milliseconds (2057 k allocations: 72842 KB, 1.72% gc time) > > > julia> @time f2(2,ones(1_000_000)); > 647.267 milliseconds (2000 k allocations: 70313 KB, 3.64% gc time) > > > julia> @time f2(2,ones(1_000_000)); > 633.149 milliseconds (2000 k allocations: 70313 KB, 0.91% gc time) > > > On Wednesday, June 17, 2015 at 12:04:52 PM UTC-4, Seth wrote: >> >> Sorry - it's part of a function: >> >> in_edges(g::AbstractGraph, v::Int) = [Edge(x,v) for x in badj(g,v)] >> >> vs >> >> in_edges(g::AbstractGraph, v::Int) = map(x->Edge(x,v), badj(g,v)) >> >> >> >> >> On Wednesday, June 17, 2015 at 10:51:22 AM UTC-5, Mauro wrote: >>> >>> Note that inside a module is also global scope as each module has its >>> own global scope. Best move it into a function. M >>> >>> On Wed, 2015-06-17 at 17:22, Seth <[email protected]> wrote: >>> > The speedups are both via the REPL (global scope?) and inside a >>> module. I >>> > did a code_native on both - results are >>> > here: https://gist.github.com/sbromberger/b5656189bcece492ffd9. >>> > >>> > >>> > >>> > On Wednesday, June 17, 2015 at 9:56:22 AM UTC-5, Stefan Karpinski >>> wrote: >>> >> >>> >> I would have expected the comprehension to be faster. Is this in >>> global >>> >> scope? If so you may want to try the speed comparison again where >>> each of >>> >> these occur in a function body and only depend on function arguments. >>> >> >>> >> On Tue, Jun 16, 2015 at 10:12 AM, Seth <[email protected] >>> >> <javascript:>> wrote: >>> >> >>> >>> I have been using list comprehensions of the form >>> >>> bar(g, a) = [Pair(x, g) for x in a] and [foo(x) for x in a] >>> >>> >>> >>> but recently evaluated bar(g, a) = map(x->Pair(x, g),a) and >>> >>> map(x->foo(x),a)as substitutes. >>> >>> >>> >>> It seems from some limited testing that map is slightly faster than >>> the >>> >>> list comprehension, but it's on the order of 3-4% so it may just be >>> noise. >>> >>> Allocations and gc time are roughly equal (380M allocations, >>> ~27000MB, ~6% >>> >>> gc). >>> >>> >>> >>> Should I prefer one approach over the other (and if so, why)? >>> >>> >>> >>> Thanks! >>> >>> >>> >> >>> >> >>> >>>
