more stuff

Author: CarloLucibello

src/GNNGraphs/GNNGraphs.jl

@@ -36,6 +36,7 @@ export adjacency_list,
        adjacency_matrix, 
        degree, 
        has_self_loops,
+       has_isolated_nodes,
        inneighbors,
        outneighbors 
 

src/GNNGraphs/query.jl

@@ -240,6 +240,17 @@ function Graphs.degree(g::GNNGraph{<:ADJMAT_T}, T::TT=nothing; dir=:out, edge_we
                   vec(sum(A, dims=1)) .+ vec(sum(A, dims=2)) 
 end
 
+"""
+    has_isolated_nodes(g::GNNGraph; dir=:out)
+
+Return true if the graph `g` contains nodes with out-degree (if `dir=:out`)
+or in-degree (if `dir=:in`) equal to zero.
+"""
+function has_isolated_nodes(g::GNNGraph; dir=:out)
+    return any(iszero, degree(g; dir))
+end
+
+
 function Graphs.laplacian_matrix(g::GNNGraph, T::DataType=eltype(g); dir::Symbol=:out)
     A = adjacency_matrix(g, T; dir=dir)
     D = Diagonal(vec(sum(A; dims=2)))

test/GNNGraphs/query.jl

@@ -29,6 +29,14 @@
         end
     end
 
+    @testset "has_isolated_nodes" begin
+        s = [1, 2, 3]
+        t = [2, 3, 2]
+        g = GNNGraph(s, t, graph_type=GRAPH_T)
+        @test has_isolated_nodes(g) == false
+        @test has_isolated_nodes(g, dir=:in) == true
+    end
+
     @testset "has_self_loops" begin
         s = [1, 1, 2, 3]
         t = [2, 2, 2, 4]

test/GNNGraphs/transform.jl

@@ -239,7 +239,7 @@
 
     @testset "to_unidirected" begin
         if GRAPH_T == :coo
-            s = [1, 2, 3, 4, 4], 
+            s = [1, 2, 3, 4, 4]
             t = [2, 3, 4, 3, 4] 
             w = [1.0, 2.0, 3.0, 4.0, 5.0]
             e = [10.0, 20.0, 30.0, 40.0, 50.0]