Merge pull request #23 from abhinavmehndiratta/write_dot

Added functionality to save graphs in DOT format

Author: sbromberger

src/DOT/Dot.jl

@@ -4,12 +4,42 @@ using GraphIO.ParserCombinator.Parsers
 using LightGraphs
 using LightGraphs: AbstractGraphFormat
 
-import LightGraphs: loadgraph, loadgraphs
+import LightGraphs: loadgraph, loadgraphs, savegraph
 
 export DOTFormat
 
 struct DOTFormat <: AbstractGraphFormat end
-# TODO: implement save
+
+function savedot(io::IO, g::LightGraphs.AbstractGraph, gname::String = "")
+    isdir = LightGraphs.is_directed(g)
+    println(io,(isdir ? "digraph " : "graph ") * gname * " {")
+    for i in LightGraphs.vertices(g)
+         println(io,"\t" * string(i))
+    end
+    if isdir
+        for u in LightGraphs.vertices(g)
+            out_nbrs = LightGraphs.outneighbors(g, u)
+            length(out_nbrs) == 0 && continue
+            println(io, "\t" * string(u) * " -> {" * join(out_nbrs,',') * "}")
+        end
+    else
+        for e in LightGraphs.edges(g)
+            source = string(LightGraphs.src(e))
+            dest = string(LightGraphs.dst(e))
+            println(io, "\t" * source * " -- " * dest)
+        end
+    end
+    println(io,"}")
+    return 1
+end
+
+function savedot_mult(io::IO, graphs::Dict)
+    ng = 0
+    for (gname, g) in graphs
+        ng += savedot(io, g, gname)
+    end
+    return ng
+end
 
 function _dot_read_one_graph(pg::Parsers.DOT.Graph)
     isdir = pg.directed
@@ -55,5 +85,7 @@ end
 
 loadgraph(io::IO, gname::String, ::DOTFormat) = loaddot(io, gname)
 loadgraphs(io::IO, ::DOTFormat) = loaddot_mult(io)
+savegraph(io::IO, g::AbstractGraph, gname::String, ::DOTFormat) = savedot(io, g, gname)
+savegraph(io::IO, d::Dict, ::DOTFormat) = savedot_mult(io, d)
 
 end #module

test/DOT/runtests.jl

@@ -1,6 +1,7 @@
 using Test
 using ParserCombinator
 using GraphIO.DOT
+using LightGraphs.Experimental
 
 @testset "DOT" begin
     g = CompleteGraph(6)
@@ -12,4 +13,35 @@ using GraphIO.DOT
     read_test(DOTFormat(), g, "g1", fname, testfail=true)
     read_test(DOTFormat(), dg, "g2", fname)
     read_test_mult(DOTFormat(), Dict{String,AbstractGraph}("g1"=>g, "g2"=>dg), fname)
+	
+	#tests for multiple graphs
+
+	fname = joinpath(testdir, "testdata", "saved3graphs.dot")
+	#connected graph
+	g1 = SimpleGraph(5,10)	
+	#disconnected graph
+	g2 = SimpleGraph(5,2)
+	#directed graph
+	dg = SimpleDiGraph(5,8)
+	GraphDict = Dict("g1" => g1, "g2" => g2, "dg" => dg)
+	write_test(DOTFormat(), GraphDict, fname, remove = false, silent = true)
+
+	#adding this test because currently the Parser returns unordered vertices
+	@test has_isomorph(loadgraph(fname, "g1", DOTFormat()), g1)
+	@test has_isomorph(loadgraph(fname, "g2", DOTFormat()), g2)
+	@test has_isomorph(loadgraph(fname, "dg", DOTFormat()), dg)
+
+	rm(fname)
+
+	#tests for single graph
+
+	fname1 = joinpath(testdir, "testdata", "saved1graph.dot")
+	write_test(DOTFormat(), g1, "g1", fname1, remove = false, silent = true)
+	@test has_isomorph(loadgraph(fname1, "g1", DOTFormat()), g1)
+	fname2 = joinpath(testdir, "testdata", "saved1digraph.dot")
+	write_test(DOTFormat(), dg, "dg", fname2, remove = false, silent = true)
+	@test has_isomorph(loadgraph(fname2, "dg", DOTFormat()), dg)	
+
+	rm(fname1)
+	rm(fname2)	
 end