Functionalities (#36)

* add hypergraphs builing models

* add models.jl and test

* add random model.jl functions

* add remove_hyperedge! and clean!

* update for pull request #36

* Co-authored-by: Alessia Antelmi <[email protected]>

src/SimpleHypergraphs.jl

@@ -10,7 +10,7 @@ using JSON3
 using JSON
 
 export Hypergraph, getvertices, gethyperedges
-export add_vertex!, add_hyperedge!, remove_vertex!
+export add_vertex!, add_hyperedge!, remove_vertex!, remove_hyperedge!, prune_hypergraph!, prune_hypergraph
 export set_vertex_meta!, get_vertex_meta
 export set_hyperedge_meta!, get_hyperedge_meta
 export BipartiteView, shortest_path

src/hypergraph.jl

@@ -255,6 +255,7 @@ function remove_vertex!(h::Hypergraph, v::Int)
     h
 end
 
+
 """
     add_hyperedge!(h::Hypergraph{T, V, E, D};
                    vertices::D = D(), he_meta::Union{E,Nothing}=nothing
@@ -280,6 +281,57 @@ function add_hyperedge!(h::Hypergraph{T, V, E, D};
     ix
 end
 
+"""
+    remove_hyperedge!(h::Hypergraph, e::Int)
+Removes the heyperedge `e` from a given hypergraph `h`.
+Note that running this function will cause reordering of hyperedges in the
+hypergraph: the hyperedge `e` will replaced by the last hyperedge of the hypergraph
+and the list of hyperedges will be shrunk.
+"""
+function remove_hyperedge!(h::Hypergraph, e::Int)
+    ne = nhe(h)
+	@assert(e <= ne)
+	if e < ne
+	    h.he2v[e] = h.he2v[ne]
+	    h.he_meta[e] = h.he_meta[ne]
+	end
+
+    for he in h.v2he
+	    if e < ne && haskey(he, ne)
+		    he[e] = he[ne]
+            delete!(he, ne)
+		else
+			delete!(he, e)
+		end
+    end
+    resize!(h.he2v, length(h.he2v) - 1)
+    h
+end
+
+"""
+    prune_hypergraph!(h::Hypergraph)
+Removes all vertices with degree 0 and all hyperedges of size 0.
+"""
+
+function prune_hypergraph!(h::Hypergraph)
+	for e in reverse(1:nhe(h))
+        length(h.he2v[e]) == 0 && remove_hyperedge!(h,e)
+    end
+	for v in reverse(1:nhv(h))
+    	length(h.v2he[v]) == 0 && 	remove_vertex!(h,v)
+    end
+	h
+end
+
+"""
+    prune_hypergraph(h::Hypergraph)
+Returns a pruned copy of `h`, removing all vertices with degree 0 and all hyperedges of size 0.
+"""
+
+function prune_hypergraph(h::Hypergraph)
+    prune_hypergraph!(deepcopy(h))
+end
+
 """
     set_vertex_meta!(h::Hypergraph{T, V, E, D}, new_value::Union{V,Nothing},
         id::Int) where {T <: Real, V, E, D <: AbstractDict{Int,T}}

src/models.jl

@@ -152,4 +152,4 @@ function next_nodes(h::Hypergraph, size::Int)
         deleteat!(ids, index)
     end
     nodes
-end
+end

test/runtests.jl

@@ -30,7 +30,7 @@ h1[5,2] = 6.5
 
     Hᵣ3  = random_model(5,1)
     @test nhe(Hᵣ3) == 1
-   
+
     Hκ = random_kuniform_model(5, 5, 3)
     @test nhv(Hκ) == 5
     @test nhe(Hκ) == 5
@@ -168,6 +168,21 @@ end;
     setindex!(h1_0, nothing, 1, 1)
     @test h1_0[1,1] == nothing
     @test_throws BoundsError setindex!(h1_0, nothing, 10, 9)
+
+    h1_1 = Hypergraph([nothing nothing nothing nothing
+                       1       1       nothing nothing
+                       nothing nothing 1       nothing
+                       nothing nothing 1       nothing])
+    @test add_hyperedge!(h1_1) == 5
+    @test size(remove_hyperedge!(h1_1, 5))[2] == 4
+    @test add_vertex!(h1_1) == 5
+    @test add_hyperedge!(h1_1) == 5
+    hp = prune_hypergraph(h1_1)
+    @test size(hp)[1] == 3 && size(h)[1] == 4 
+    @test size(hp)[2] == 3 && size(h)[1] == 4 
+    prune_hypergraph!(h1_1)
+    @test size(h1_1)[1] == 3
+    @test size(h1_1)[2] == 3
 end;
 
 @testset "SimpleHypergraphs BipartiteView   " begin