The following is faster, though it does not scale very well for large
indices because of ridiculous if chains...
```
@generated function droptup{N,T,i}(x::NTuple{N,T}, ::Type{Val{i}})
@assert 1 <= i <= N
args = [:(x[$j]) for j in deleteat!([1:N...], i)]
Expr(:tuple, args...)
end
@generated function droptup{N,T}(x::NTuple{N,T}, i::Int)
quote
@nif $N d->(i==d) d-> droptup(x, Val{d})
end
end
using BenchmarkTools
x = (10,20,30,40)
@benchmark droptup($x, 4)
```
BenchmarkTools.Trial:
samples: 10000
evals/sample: 1000
time tolerance: 5.00%
memory tolerance: 1.00%
memory estimate: 0.00 bytes
allocs estimate: 0
minimum time: 6.00 ns (0.00% GC)
median time: 6.00 ns (0.00% GC)
mean time: 6.11 ns (0.00% GC)
maximum time: 70.00 ns (0.00% GC)
On Friday, June 24, 2016 at 4:50:59 PM UTC+2, jw3126 wrote:
>
> Okay thanks, it works! However it has extremely poor performance. I would
> love to do this stack allocated.
>
> ```
> using BenchmarkTools
> function subtuple(t::Tuple,i::Integer)
> idx = 1:length(t)
> idx = setdiff(idx,i)
> t[idx]
> end
>
> @benchmark subtuple($(1,2,3,4), $1)
> ```
>
> BenchmarkTools.Trial:
> samples: 10000
> evals/sample: 10
> time tolerance: 5.00%
> memory tolerance: 1.00%
> memory estimate: 1.33 kb
> allocs estimate: 22
> minimum time: 1.52 μs (0.00% GC)
> median time: 1.69 μs (0.00% GC)
> mean time: 1.96 μs (9.07% GC)
> maximum time: 323.58 μs (98.21% GC)
>
>
> On Friday, June 24, 2016 at 4:42:17 PM UTC+2, STAR0SS wrote:
>>
>> You can do something like that:
>>
>> t = tuple(1,2,3,4)
>>
>> function subtuple(t::Tuple,i::Integer)
>> idx = 1:length(t)
>> idx = setdiff(idx,i)
>> t[idx]
>> end
>>
>> subtuple(t,3)
>>
>> (1,2,4)
>>
>
