# Cannot write txt file on julia(distance map)

**URL:** <https://discourse.julialang.org/t/cannot-write-txt-file-on-julia-distance-map/90626>\
**Category:** General Usage\
**Created:** [November 22, 2022, 5:21am UTC](https://discourse.julialang.org/t/cannot-write-txt-file-on-julia-distance-map/90626 "2022-11-22T05:21:58Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![dangda](https://avatars.discourse-cdn.com/v4/letter/d/bc8723/32.png) [@dangda](https://discourse.julialang.org/u/dangda)\
**Post date:** [November 22, 2022, 5:21am UTC](https://discourse.julialang.org/t/cannot-write-txt-file-on-julia-distance-map/90626/1 "2022-11-22T05:21:58Z")

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print(dm)  
Distance map of size (398, 398)  
julia\> using DelimitedFiles

julia\> writedlm(“dmdm.txt”,dm)  
ERROR: MethodError: no method matching iterate(::DistanceMap)  
Closest candidates are:  
iterate(::Union{LinRange, StepRangeLen}) at range.jl:664  
iterate(::Union{LinRange, StepRangeLen}, ::Int64) at range.jl:664  
iterate(::T) where T\<:Union{Base.KeySet{var"#s77", var"#s76"} where {var"#s77", var"#s76"\<:Dict}, Base.ValueIterator{var"#s75"} where var"#s75"\<:Dict} at dict.jl:693  
…  
Stacktrace:  
[1] writedlm(io::IOStream, itr::DistanceMap, dlm::Char; opts::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})  
@ DelimitedFiles /builddir/build/BUILD/julia-1.6.5/build/usr/share/julia/stdlib/v1.6/DelimitedFiles/src/DelimitedFiles.jl:779  
[2] writedlm(io::IOStream, itr::DistanceMap, dlm::Char)  
@ DelimitedFiles /builddir/build/BUILD/julia-1.6.5/build/usr/share/julia/stdlib/v1.6/DelimitedFiles/src/DelimitedFiles.jl:776  
[3] (::DelimitedFiles.var"#16#17"{Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, DistanceMap, Char})(io::IOStream)  
@ DelimitedFiles /builddir/build/BUILD/julia-1.6.5/build/usr/share/julia/stdlib/v1.6/DelimitedFiles/src/DelimitedFiles.jl:789  
[4] open(::DelimitedFiles.var"#16#17"{Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, DistanceMap, Char}, ::String, ::Vararg{String, N} where N; kwargs::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})  
@ Base ./io.jl:330  
[5] writedlm(fname::String, a::DistanceMap, dlm::Char; opts::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})  
@ DelimitedFiles /builddir/build/BUILD/julia-1.6.5/build/usr/share/julia/stdlib/v1.6/DelimitedFiles/src/DelimitedFiles.jl:788  
[6] writedlm(fname::String, a::DistanceMap, dlm::Char)  
@ DelimitedFiles /builddir/build/BUILD/julia-1.6.5/build/usr/share/julia/stdlib/v1.6/DelimitedFiles/src/DelimitedFiles.jl:788  
[7] writedlm(io::String, a::DistanceMap; opts::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})  
@ DelimitedFiles /builddir/build/BUILD/julia-1.6.5/build/usr/share/julia/stdlib/v1.6/DelimitedFiles/src/DelimitedFiles.jl:826  
[8] writedlm(io::String, a::DistanceMap)  
@ DelimitedFiles /builddir/build/BUILD/julia-1.6.5/build/usr/share/julia/stdlib/v1.6/DelimitedFiles/src/DelimitedFiles.jl:826  
[9] top-level scope  
@ REPL[54]:1

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**Author:** ![LeePhillips](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/leephillips/32/205514_2.png) [@LeePhillips](https://discourse.julialang.org/u/LeePhillips)\
**Post date:** [November 22, 2022, 8:26pm UTC](https://discourse.julialang.org/t/cannot-write-txt-file-on-julia-distance-map/90626/2 "2022-11-22T20:26:50Z")

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If you type `?writedlm` in the REPL the help system will explain that the second argument needs to be “a vector, matrix, or an iterable collection of iterable rows”. Looks like this `dm` thing is not that. To persist arbitrary Julia datatypes to disk, you might look at the `JLD.jl` package.

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**Author:** ![cchderrick](https://avatars.discourse-cdn.com/v4/letter/c/ecd19e/32.png) [@cchderrick](https://discourse.julialang.org/u/cchderrick)\
**Post date:** [November 22, 2022, 8:32pm UTC](https://discourse.julialang.org/t/cannot-write-txt-file-on-julia-distance-map/90626/3 "2022-11-22T20:32:34Z")

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In order to get more help, I think you need to describe this `DistanceMap` type? How is the data layout? Can it be access like “an iterable collection of iterable rows”.