SubArrays cause an illegal naming error

[tyleransom]

If I try to save a SubArray (created from the @views macro) to a MAT file, I get an illegal naming error. Consider the following MWE using MAT.jl v0.10.1:

using Random, MAT

Random.seed!(1234)
a = rand(5)
@show a
@show typeof(a)
@views a = a[[1,3,4,2,5]]
@show a
@show typeof(a)

matwrite("test.mat", Dict("a" => a))

This returns the following:

julia> include("MWE.jl")
a = [0.5908446386657102, 0.7667970365022592, 0.5662374165061859, 0.4600853424625171, 0.7940257103317943]
typeof(a) = Array{Float64,1}
a = [0.5908446386657102, 0.5662374165061859, 0.4600853424625171, 0.7667970365022592, 0.7940257103317943]
typeof(a) = SubArray{Float64,1,Array{Float64,1},Tuple{Array{Int64,1}},false}
ERROR: LoadError: Invalid variable name or key "1": variable names must start with a letter and contain only alphanumeric characters and underscore
Stacktrace:
 [1] error(::String) at ./error.jl:33
 [2] check_valid_varname at /hpc/home/tmr17/.julia/packages/MAT/f523T/src/MAT_HDF5.jl:290 [inlined]
 [3] check_struct_keys(::Array{String,1}) at /hpc/home/tmr17/.julia/packages/MAT/f523T/src/MAT_HDF5.jl:507
 [4] m_write(::MAT.MAT_HDF5.MatlabHDF5File, ::HDF5.Group, ::String, ::Tuple{Array{Int64,1}}) at /hpc/home/tmr17/.julia/packages/MAT/f523T/src/MAT_HDF5.jl:533
 [5] m_write(::MAT.MAT_HDF5.MatlabHDF5File, ::HDF5.File, ::String, ::Array{String,1}, ::Array{Any,1}) at /hpc/home/tmr17/.julia/packages/MAT/f523T/src/MAT_HDF5.jl:518
 [6] m_write(::MAT.MAT_HDF5.MatlabHDF5File, ::HDF5.File, ::String, ::SubArray{Float64,1,Array{Float64,1},Tuple{Array{Int64,1}},false}) at /hpc/home/tmr17/.julia/packages/MAT/f523T/src/MAT_HDF5.jl:533
 [7] write(::MAT.MAT_HDF5.MatlabHDF5File, ::String, ::SubArray{Float64,1,Array{Float64,1},Tuple{Array{Int64,1}},false}) at /hpc/home/tmr17/.julia/packages/MAT/f523T/src/MAT_HDF5.jl:546
 [8] matwrite(::String, ::Dict{String,SubArray{Float64,1,Array{Float64,1},Tuple{Array{Int64,1}},false}}; compress::Bool) at /hpc/home/tmr17/.julia/packages/MAT/f523T/src/MAT.jl:157
 [9] matwrite(::String, ::Dict{String,SubArray{Float64,1,Array{Float64,1},Tuple{Array{Int64,1}},false}}) at /hpc/home/tmr17/.julia/packages/MAT/f523T/src/MAT.jl:148
 [10] top-level scope at /hpc/group/econ/tmr17/DropoutRR/Simulations/BackwardSimMay2020/MWE.jl:11
 [11] include(::String) at ./client.jl:439
 [12] top-level scope at REPL[1]:1
in expression starting at /hpc/group/econ/tmr17/DropoutRR/Simulations/BackwardSimMay2020/MWE.jl:11

[matthijscox]

Seems to work fine for me now, maybe an old issue?

julia> a = view([1.0, 2.0, 3.0], [1,3])
2-element view(::Vector{Float64}, [1, 3]) with eltype Float64:
 1.0
 3.0

julia> matwrite("test.mat", Dict("a" => a))

julia> matread("test.mat")
Dict{String, Any} with 1 entry:
  "a" => [1.0, 3.0]

[tyleransom]

Thanks for responding, @matthijscox. I get the same error when I run the code you just showed:

julia> a = view([1.0, 2.0, 3.0], [1,3])
2-element view(::Vector{Float64}, [1, 3]) with eltype Float64:
 1.0
 3.0

julia> matwrite("test.mat", Dict("a" => a))
ERROR: Invalid variable name or key "1": variable names must start with a letter and contain only alphanumeric characters and underscore
Stacktrace:
  [1] error(s::String)
    @ Base .\error.jl:35
  [2] check_valid_varname
    @ C:\Users\me\.julia\packages\MAT\K2D15\src\MAT_HDF5.jl:292 [inlined]
  [3] check_struct_keys(k::Vector{String})
    @ MAT.MAT_HDF5 C:\Users\me\.julia\packages\MAT\K2D15\src\MAT_HDF5.jl:509
  [4] m_write(mfile::MAT.MAT_HDF5.MatlabHDF5File, parent::HDF5.Group, name::String, s::Tuple{Vector{Int64}})
    @ MAT.MAT_HDF5 C:\Users\me\.julia\packages\MAT\K2D15\src\MAT_HDF5.jl:535
  [5] m_write(mfile::MAT.MAT_HDF5.MatlabHDF5File, parent::HDF5.File, name::String, k::Vector{String}, v::Vector{Any})
    @ MAT.MAT_HDF5 C:\Users\me\.julia\packages\MAT\K2D15\src\MAT_HDF5.jl:520
  [6] m_write(mfile::MAT.MAT_HDF5.MatlabHDF5File, parent::HDF5.File, name::String, s::SubArray{…})
    @ MAT.MAT_HDF5 C:\Users\me\.julia\packages\MAT\K2D15\src\MAT_HDF5.jl:535
  [7] write(parent::MAT.MAT_HDF5.MatlabHDF5File, name::String, thing::SubArray{Float64, 1, Vector{…}, Tuple{…}, false})
    @ MAT.MAT_HDF5 C:\Users\me\.julia\packages\MAT\K2D15\src\MAT_HDF5.jl:548
  [8] matwrite(filename::String, dict::Dict{String, SubArray{…}}; compress::Bool, version::String)
    @ MAT C:\Users\me\.julia\packages\MAT\K2D15\src\MAT.jl:178
  [9] matwrite(filename::String, dict::Dict{String, SubArray{Float64, 1, Vector{Float64}, Tuple{Vector{Int64}}, false}})
    @ MAT C:\Users\me\.julia\packages\MAT\K2D15\src\MAT.jl:148
 [10] top-level scope
    @ REPL[8]:1
Some type information was truncated. Use `show(err)` to see complete types.

I'm on Windows 11, Julia version 1.11.4.

[matthijscox]

Okay, will have another look, perhaps this was somehow fixed on the master branch (which is not yet released, we are working on v0.11 MAT.jl).

If you have time maybe you can try the latest master branch version? I think this should work: pkg>add MAT#master

[tyleransom]

Thanks, @matthijscox! It works on v0.11.