Error for graphs with self loops

[mtfishman]

Minimal example:

julia> using LightGraphs, NetworkLayout

julia> g = Graph(Edge.([1 => 2, 2 => 3]))
{3, 2} undirected simple Int64 graph

julia> Spring()(g)
3-element Vector{GeometryBasics.Point2{Float64}}:
 [-3.127142160281595, -0.30807599829163085]
 [-0.6142712514773444, -1.155509538576658]
 [1.8599722110838215, -1.9899164671852727]

julia> add_edge!(g, 1 => 1)
true

julia> Spring()(g)
ERROR: ArgumentError: Illegal buffers for SparseMatrixCSC construction 3 [1, 3, 5, 6] [1, 2, 1, 3, 2] [1, 1, 1, 1, 1, 1]
Stacktrace:
 [1] SparseMatrixCSC
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.7/SparseArrays/src/sparsematrix.jl:29 [inlined]
 [2] SparseArrays.SparseMatrixCSC(m::Int64, n::Int64, colptr::Vector{Int64}, rowval::Vector{Int64}, nzval::Vector{Int64})
   @ SparseArrays /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.7/SparseArrays/src/sparsematrix.jl:44
 [3] _adjacency_matrix(g::SimpleGraph{Int64}, T::DataType, neighborfn::typeof(inneighbors), nzmult::Int64)
   @ LightGraphs.LinAlg ~/.julia/packages/LightGraphs/IgJif/src/linalg/spectral.jl:63
 [4] #adjacency_matrix#2
   @ ~/.julia/packages/LightGraphs/IgJif/src/linalg/spectral.jl:25 [inlined]
 [5] adjacency_matrix (repeats 2 times)
   @ ~/.julia/packages/LightGraphs/IgJif/src/linalg/spectral.jl:20 [inlined]
 [6] layout
   @ ~/.julia/packages/NetworkLayout/TxHy6/src/NetworkLayout.jl:91 [inlined]
 [7] (::Spring{2, Float64})(adj_matrix::SimpleGraph{Int64})
   @ NetworkLayout ~/.julia/packages/NetworkLayout/TxHy6/src/NetworkLayout.jl:34
 [8] top-level scope
   @ REPL[19]:1

EDIT: This appears to be specific to Julia 1.7, see sbromberger/LightGraphs.jl#1594.

[mtfishman]

I guess this is actually a LightGraphs issue:

julia> using LightGraphs

julia> g = Graph(Edge.([1 => 2, 2 => 3]))
{3, 2} undirected simple Int64 graph

julia> adjacency_matrix(g)
3×3 SparseArrays.SparseMatrixCSC{Int64, Int64} with 4 stored entries:
 ⋅  1  ⋅
 1  ⋅  1
 ⋅  1  ⋅

julia> add_edge!(g, 1 => 1)
true

julia> adjacency_matrix(g)
ERROR: ArgumentError: Illegal buffers for SparseMatrixCSC construction 3 [1, 3, 5, 6] [1, 2, 1, 3, 2] [1, 1, 1, 1, 1, 1]
Stacktrace:
 [1] SparseMatrixCSC
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.7/SparseArrays/src/sparsematrix.jl:29 [inlined]
 [2] SparseArrays.SparseMatrixCSC(m::Int64, n::Int64, colptr::Vector{Int64}, rowval::Vector{Int64}, nzval::Vector{Int64})
   @ SparseArrays /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.7/SparseArrays/src/sparsematrix.jl:44
 [3] _adjacency_matrix(g::SimpleGraph{Int64}, T::DataType, neighborfn::typeof(inneighbors), nzmult::Int64)
   @ LightGraphs.LinAlg ~/.julia/packages/LightGraphs/IgJif/src/linalg/spectral.jl:63
 [4] #adjacency_matrix#2
   @ ~/.julia/packages/LightGraphs/IgJif/src/linalg/spectral.jl:25 [inlined]
 [5] adjacency_matrix (repeats 2 times)
   @ ~/.julia/packages/LightGraphs/IgJif/src/linalg/spectral.jl:20 [inlined]
 [6] top-level scope
   @ REPL[28]:1

[hexaeder]

Interesting I've been using self edges in GraphMakie without a problem http://juliaplots.org/GraphMakie.jl/stable/generated/plots/#Self-edges

Edit: Ah you allready mentioned that it works well on 1.6

[mtfishman]

See: sbromberger/LightGraphs.jl#1594 it looks like it is specific to Julia 1.7.

[mtfishman]

@hexaeder on a separate note, GraphMakie looks great! I built my own interactive graph visualization tool here: https://github.com/ITensor/ITensorsVisualization.jl (specific to visualizing tensor networks, but it would pretty be easy to generalize). However it has become pretty outdated from that latest Makie versions, I will try out using your package as a backend.

[hexaeder]

Your upstream fix was released in [email protected] :)