Catlab.jl : Facing error while creating simple graphs

Specific Domains Graphs
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1

I was following the AlgebraicJulia blog for Graphs and C-sets where I am encountering an IOError for the ‘dot -Tsvg’ file missing when trying to generate graph interface using the 'to_graphviz() function. I could not debug the error as it is not very clear to me. I am using the same code as mentioned in the blog, but for ease posting the code:

using Catlab

using Catlab.CategoricalAlgebra

using Catlab.Theories

using Catlab.Graphs

using Catlab.Graphics

@present SchGraph(FreeSchema) begin

V::Ob

E::Ob

src::Hom(E,V)

tgt::Hom(E,V)

end

g = Graph()

add_parts!(g, :V, 3)

add_parts!(g, :E, 4, src=[1,2,2,3], tgt=[2,3,3,3])

g

to_graphviz(g)

Error message:

ERROR: IOError: could not spawn `dot -Tsvg`: no such file or directory (ENOENT)

Any help would be very much appreciated.

2

Guessing from the error message it seems you don’t have Graphviz installed (dot is one of the command line tools from graphviz).

3

As a matter of fact, I do have it.
image

4

Ok, that seems to be another Julia package wrapping Graphviz. I was thinking of the Graphviz library/tools which are run under the hood.
Can you run dot from the command line, i.e., outside of Julia?

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5

Yep, this was the problem, I installed Graphviz from the link you gave.
It works now.
Thanks for the help, really appreciated.

6

Even though the problem has been solved, as a fellow Catlab user I’ll just point out that Catlab assumes one of two things 1. the user has installed graphviz_jll, or 2. Graphviz (the software itself, not necessarily the julia package of the same name) itself has been installed and is accessible from the command line.

See the comments/code here Catlab.jl/src/graphics/Graphviz.jl at 2092b5b3610dbaec921bd840da952ae27dbc97e9 · AlgebraicJulia/Catlab.jl (github.com)

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