# DArray local part via global index range?

**URL:** <https://discourse.julialang.org/t/darray-local-part-via-global-index-range/53298>\
**Category:** Performance\
**Tags:** question\
**Created:** [January 13, 2021, 6:22pm UTC](https://discourse.julialang.org/t/darray-local-part-via-global-index-range/53298 "2021-01-13T18:22:30Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![mkarikom](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mkarikom/32/7096_2.png) [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Post date:** [January 13, 2021, 6:22pm UTC](https://discourse.julialang.org/t/darray-local-part-via-global-index-range/53298/1 "2021-01-13T18:22:30Z")

</div>

I’d like to be able to get the local part via global indexing (without resorting to `:L`) in order to facilitate portability with SharedArrays.

How can I fix the following:

```julia-auto
using Test,Distributed,DistributedArrays

nwork = 5
while length(workers()) < nwork
    addprocs(1)
end

@everywhere using DistributedArrays

@testset "explicit local part" begin
    a = @DArray [i+j for i = 1:5, j = 1:5]
    @test all(@fetchfrom 2 a[1:5] .== @fetchfrom 2 a[:L])
    @test all(@fetchfrom 2 a[:L][1:3] .== @fetchfrom 2 a[1:5][1:3])
end

```

### Output:

```julia-auto
julia> @testset "explicit local part" begin
       a = @DArray [i+j for i = 1:5, j = 1:5]
       @test all(@fetchfrom 2 a[1:5] .== @fetchfrom 2 a[:L])
       @test all(@fetchfrom 2 a[:L][1:3] .== @fetchfrom 2 a[1:5][1:3])
       end
explicit local part: Error During Test at REPL[53]:4
  Test threw exception
  Expression: all(#= REPL[53]:4 =# @fetchfrom(2, (a[:L])[1:3] .== #= REPL[53]:4 =# @fetchfrom(2, (a[1:5])[1:3])))
  On worker 2:
  setindex! not defined for DArray{Int64,1,Array{Int64,1}}
  error at ./error.jl:42
  error_if_canonical_setindex at ./abstractarray.jl:1163
  setindex! at ./abstractarray.jl:1152 [inlined]
  macro expansion at ./multidimensional.jl:772 [inlined]
  macro expansion at ./cartesian.jl:64 [inlined]
  macro expansion at ./multidimensional.jl:767 [inlined]
  _unsafe_getindex! at ./multidimensional.jl:762
  _unsafe_getindex at ./multidimensional.jl:757
  _getindex at ./multidimensional.jl:743
  getindex at ./abstractarray.jl:1060 [inlined]
  #88 at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:149 [inlined]
  run_work_thunk at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:79
  #remotecall_fetch#142 at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:379 [inlined]
  remotecall_fetch at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:379 [inlined]
  #remotecall_fetch#146 at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421 [inlined]
  remotecall_fetch at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421 [inlined]
  #87 at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:149
  #106 at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:294
  run_work_thunk at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:79
  macro expansion at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:294 [inlined]
  #105 at ./task.jl:356
  Stacktrace:
   [1] #remotecall_fetch#143 at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:394 [inlined]
   [2] remotecall_fetch(::Function, ::Distributed.Worker) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:386
   [3] remotecall_fetch(::Function, ::Int64; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421
   [4] remotecall_fetch(::Function, ::Int64) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421
   [5] top-level scope at REPL[53]:4
   [6] top-level scope at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Test/src/Test.jl:1115
   [7] top-level scope at REPL[53]:2
  
Test Summary: | Pass Error Total
explicit local part | 1 1 2
ERROR: Some tests did not pass: 1 passed, 0 failed, 1 errored, 0 broken.

```