subset(xs,k) vs subset(xs) vs combinations(xs,k)

[christophfeinauer]

Hi,

is there a reason why there is an extra implementation for subset(xs)? chain([subsets(xs,n) for n=0:length(xs)]...) seems to do the same thing and is faster for me:

allsubsets(xs) = chain([subsets(xs,n) for n=0:length(xs)]...)
function test1()
        n = 20
        set = rand(n)
        for s = subsets(set)
                rand()
        end
end
function test2()
        n = 20
        set = rand(n)
        for s = allsubsets(set)
                rand()
        end
end
julia> test1(); test2(); @time test1(); @time test2();
  3.905233 seconds (40.63 M allocations: 1.261 GB, 4.52% gc time)
  1.446248 seconds (8.39 M allocations: 356.006 MB, 2.36% gc time)

Also, doesn't Base.combinations(xs,k) do the same thing as subsets(xs,k)?

[iamed2]

Since you posted this, Base.combinations is deprecated.

The performance issue is now dealt with in #73. subsets(xs) was not very performant; it is now.