Enable ordinal indexing of DataGraph

ext/DataGraphsNamedGraphsExt/DataGraphsNamedGraphsExt.jl

@@ -11,4 +11,30 @@ for f in [:(NamedGraphs.position_graph), :(NamedGraphs.vertex_positions)]
     end
   end
 end
+
+using Graphs: edgetype, vertices
+using NamedGraphs.OrdinalIndexing: OrdinalSuffixedInteger
+# TODO: Define through some intermediate `to_vertex` function
+# (analagous to Julia's `to_indices`) instead of through
+# overloading `Base.getindex`.
+function Base.getindex(graph::AbstractDataGraph, vertex::OrdinalSuffixedInteger)
+  return graph[vertices(graph)[vertex]]
+end
+function Base.getindex(
+  graph::AbstractDataGraph, edge::Pair{<:OrdinalSuffixedInteger,<:OrdinalSuffixedInteger}
+)
+  return graph[edgetype(graph)(vertices(graph)[edge[1]], vertices(graph)[edge[2]])]
+end
+function Base.setindex!(graph::AbstractDataGraph, value, vertex::OrdinalSuffixedInteger)
+  graph[vertices(graph)[vertex]] = value
+  return graph
+end
+function Base.setindex!(
+  graph::AbstractDataGraph,
+  value,
+  edge::Pair{<:OrdinalSuffixedInteger,<:OrdinalSuffixedInteger},
+)
+  graph[edgetype(graph)(vertices(graph)[edge[1]], vertices(graph)[edge[2]])] = value
+  return graph
+end
 end

test/runtests.jl

@@ -33,6 +33,7 @@ using GraphsFlows: GraphsFlows
 using NamedGraphs: NamedDiGraph, NamedEdge, NamedGraph
 using NamedGraphs.GraphsExtensions: ⊔, rename_vertices, vertextype
 using NamedGraphs.NamedGraphGenerators: named_grid, named_path_graph
+using NamedGraphs.OrdinalIndexing: nd, st, rd, th
 using Test: @test, @test_broken, @testset
 
 using DataGraphs: is_arranged
@@ -398,5 +399,34 @@ using DataGraphs: is_arranged
     @test verts[4] ∈ part2
     @test flow == 1
   end
+  @testset "OrdinalIndexing" begin
+    g = DataGraph(
+      NamedGraph(path_graph(3), ["a", "b", "c"]);
+      vertex_data_eltype=String,
+      edge_data_eltype=Symbol,
+    )
+    g[1st] = "v_a"
+    g[2nd] = "v_b"
+    g[3rd] = "v_c"
+    g[1st => 2nd] = :e_ab
+    g[2nd => 3rd] = :e_bc
+    @test g["a"] == "v_a"
+    @test g["b"] == "v_b"
+    @test g["c"] == "v_c"
+    @test g["a" => "b"] === :e_ab
+    @test g["b" => "a"] === :e_ab
+    @test g["b" => "c"] === :e_bc
+    @test g["c" => "b"] === :e_bc
+    @test g[1st] == "v_a"
+    @test g[1th] == "v_a"
+    @test g[2nd] == "v_b"
+    @test g[2th] == "v_b"
+    @test g[3rd] == "v_c"
+    @test g[3th] == "v_c"
+    @test g[1st => 2nd] === :e_ab
+    @test g[2nd => 1st] === :e_ab
+    @test g[2nd => 3rd] === :e_bc
+    @test g[3rd => 2nd] === :e_bc
+  end
 end
 end