Optimize `lazytree[range]` about unroot.jl HOT 9 CLOSED

julia> @btime t.Muon_pt[1:10^6];
  128.243 ms (49947 allocations: 163.46 MiB)

julia> @btime vcat([UnROOT.basketarray(t.Muon_pt, i) for i in 1:450]...);
  111.932 ms (50418 allocations: 150.14 MiB)

julia> @btime mapreduce(i->UnROOT.basketarray(t.Muon_pt, i), append!, 1:450);
  112.515 ms (49971 allocations: 139.77 MiB)

julia> @btime t.Muon_pt[1:10^6]
  192.154 ms (51297 allocations: 156.56 MiB)
1000000-element Vector{SubArray{Float32, 1, Vector{Float32}, Tuple{UnitRange{Int64}}, true}}:
 [10.763697, 15.736523]
 # ...

julia> ibasket = findfirst(>=(10^6),t.Muon_pt.b.fBasketEntry)-1
450

julia> @btime vcat([UnROOT.basketarray(t.Muon_pt, i) for i in 1:ibasket]...)
  185.263 ms (51771 allocations: 142.18 MiB)
1643390-element ArraysOfArrays.VectorOfVectors{Float32, Vector{Float32}, Vector{Int32}, Vector{Tuple{}}}:
 Float32[10.763697, 15.736523]
 # ...

julia> const b = mapreduce(i->UnROOT.basketarray(t.Muon_pt, i), append!, 1:450);

julia> length(b)
1643390

julia> const a = t.Muon_pt[1:1643390];

julia> sum(sum, a) == sum(sum,b)
true

julia> @benchmark sum(sum, a)
BenchmarkTools.Trial: 320 samples with 1 evaluation.
 Range (min … max):  15.523 ms … 15.792 ms  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     15.632 ms              ┊ GC (median):    0.00%
 Time  (mean ± σ):   15.630 ms ± 30.438 μs  ┊ GC (mean ± σ):  0.00% ± 0.00%

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  ▃▁▁▁▁▁▃▁▁▁▃▁▁▃▃▃▃▄▅▆▆▃█▄█▇███▅█████████████▄██▅▅▃▅▃▃▃▄▃▁▃▃▄ ▄
  15.5 ms         Histogram: frequency by time        15.7 ms <

 Memory estimate: 0 bytes, allocs estimate: 0.

julia> @benchmark sum(sum, b)
BenchmarkTools.Trial: 304 samples with 1 evaluation.
 Range (min … max):  16.274 ms … 16.760 ms  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     16.489 ms              ┊ GC (median):    0.00%
 Time  (mean ± σ):   16.480 ms ± 51.774 μs  ┊ GC (mean ± σ):  0.00% ± 0.00%

                                           ▃▃▂ ▄█▂▂            
  ▂▁▁▁▂▂▂▂▃▃▂▂▁▂▂▁▃▃▂▁▂▁▁▂▁▁▁▂▁▁▂▂▂▃▄▃▅▅▆▅█████████▆▅▄▅▄▄▃▅▄▃ ▃
  16.3 ms         Histogram: frequency by time        16.6 ms <

 Memory estimate: 0 bytes, allocs estimate: 0.

julia> @benchmark sum(length, a)
BenchmarkTools.Trial: 1470 samples with 1 evaluation.
 Range (min … max):  3.290 ms …  4.321 ms  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     3.384 ms              ┊ GC (median):    0.00%
 Time  (mean ± σ):   3.389 ms ± 54.861 μs  ┊ GC (mean ± σ):  0.00% ± 0.00%

             ▁▂▂▄▃▄▆▇██▇▂▂                                    
  ▃▂▃▂▂▄▃▃▆▅▇█████████████▆▅▄▃▄▃▃▃▂▂▃▂▃▃▂▁▂▃▂▂▂▂▂▂▂▂▂▁▂▁▂▁▂▂ ▄
  3.29 ms        Histogram: frequency by time        3.59 ms <

 Memory estimate: 0 bytes, allocs estimate: 0.

julia> @benchmark sum(length, b)
BenchmarkTools.Trial: 10000 samples with 1 evaluation.
 Range (min … max):  330.388 μs … 678.389 μs  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     342.481 μs               ┊ GC (median):    0.00%
 Time  (mean ± σ):   343.999 μs ±  10.849 μs  ┊ GC (mean ± σ):  0.00% ± 0.00%

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  330 μs           Histogram: frequency by time          360 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.'