UndefVarError: DOT not defined

[pauljurczak]

I'm trying to test basic functionality and I got stuck here:

julia> using LightGraphs, GraphIO

julia> graph = loadgraph("gr.dot", "gr", DOTFormat())
ERROR: UndefVarError: DOT not defined
Stacktrace:
 [1] DOTFormat() at /home/paul/.julia/packages/GraphIO/IgxnP/src/deprecations.jl:29
 [2] top-level scope at REPL[3]:1
 [3] include_string(::Function, ::Module, ::String, ::String) at ./loading.jl:1088

I'm using Julia 1.5.1 on Ubuntu 18.04.

[simonschoelly]

Some graph formats need additional packages - we did not want to make them mandatory for that package to reduce unnecessary dependencies, so you have to import them manually. I thought we had documented this in the README but apparently that is not the case.

In your case you need to install ParserCombinator and then write using ParserCombinator, then the dot format should be available.

[pauljurczak]

Thank you, it works now. One more question, if I may: I thought that graph name is optional, but skipping it doesn't work:

julia> graph = loadgraph("gr.dot", DOTFormat())
ERROR: Graph graph not found
......
julia> graph = loadgraph("gr.dot", format=DOTFormat())
ERROR: MethodError: no method matching loadgraph(::String; format=GraphIO.DOT.DOTFormat())

Am I reading https://juliagraphs.org/LightGraphs.jl/stable/persistence/#LightGraphs.loadgraphs-Tuple{AbstractString,LightGraphs.AbstractGraphFormat} wrong?

[simonschoelly]

The methods for importing dot are defined here:

GraphIO.jl/src/DOT/Dot.jl

Line 86 in eb35fe3

loadgraph(io::IO, gname::String, ::DOTFormat) = loaddot(io, gname)

, looks like the signature there is slightly different.

[pauljurczak]

So the documentation is not accurate, right?

EDIT

BTW, there is also:

loadgraphs(io::IO, ::DOTFormat) = loaddot_mult(io)

Doesn't it match loadgraph("gr.dot", DOTFormat()) ?

[pauljurczak]

Never mind. This error:

julia> graph = loadgraph("gr.dot", DOTFormat())
ERROR: Graph graph not found

was caused by graph name different from "graph".

[yonkeltron]

Is there any way to make this clear from the error message?

[sbulcsu]

Same here:
ERROR: Graph graph not found
I had to check what is the name of the graph in the .graphml file and use that one:
<graph id="G" edgedefault="directed">
as
g = loadgraph("test.graphml", "G", GraphMLFormat())

This should be added to the Documentation/README.md and/or to the error message!