add method for weights, and corresponding test

Author: Vincent Landau

src/graph_interface.jl

@@ -2,7 +2,7 @@
 ## With these methods defined, functions from Graphs should "just work"
 import Graphs: 
     nv, ne, vertices, edges, eltype, edgetype, has_edge, has_vertex,
-    inneighbors, outneighbors, is_directed, add_edge!
+    inneighbors, outneighbors, is_directed, add_edge!, weights
 
 import SimpleWeightedGraphs:
     add_edge!, get_weight, add_vertex!, vertices
@@ -21,6 +21,8 @@ has_vertex(g::AbstractSpatialGraph, v) = has_vertex(g.graph, v)
 inneighbors(g::AbstractSpatialGraph, v) = inneighbors(g.graph, v)
 outneighbors(g::AbstractSpatialGraph, v) = outneighbors(g.graph, v)
 is_directed(g::AbstractSpatialGraph) = is_directed(g.graph)
+weights(g::AbstractSpatialGraph) = weights(g.graph)
+
 function Base.zero(g::AbstractRasterGraph)
     if g.graph isa Graph
         RasterGraph(

test/graph_interface.jl

@@ -1,4 +1,4 @@
-using SpatialGraphs, Test, Rasters, Graphs, SimpleWeightedGraphs
+using SpatialGraphs, Test, Rasters, Graphs, SimpleWeightedGraphs, SparseArrays
 ## This script tests methods for the LightGraph interface that aren't already 
 ## used in other tests
 
@@ -16,6 +16,7 @@ num_edge = ne(rasgraph)
 @test vertices(rasgraph) == 1:maximum(rasgraph.vertex_raster)
 @test eltype(rasgraph) == Int # Should always be Int64 (or int32 on 32-bit)
 @test edgetype(rasgraph) == SimpleWeightedEdge{eltype(rasgraph), eltype(A_array)}
+@test typeof(weights(rasgraph)) <: SparseMatrixCSC # Make sure it's returning proper weights from the weighted graph
 
 for i in 1:maximum(rasgraph.vertex_raster)
     @test has_vertex(rasgraph, i)