Dijkstra undirected

lib/alg/dijkstra.js

@@ -6,9 +6,13 @@ module.exports = dijkstra;
 var DEFAULT_WEIGHT_FUNC = _.constant(1);
 
 function dijkstra(g, source, weightFn, edgeFn) {
+  var defaultEdgeFn = function(v) {
+    return g.outEdges(v);
+  };
+
   return runDijkstra(g, String(source),
                      weightFn || DEFAULT_WEIGHT_FUNC,
-                     edgeFn || function(v) { return g.outEdges(v); });
+                     edgeFn || defaultEdgeFn);
 }
 
 function runDijkstra(g, source, weightFn, edgeFn) {

lib/graph.js

@@ -411,8 +411,9 @@ Graph.prototype.setEdge = function() {
 
   this._edgeLabels[e] = valueSpecified ? value : this._defaultEdgeLabelFn(v, w, name);
 
-  var edgeObj = edgeArgsToObj(this._isDirected, v, w, name);
   // Ensure we add undirected edges in a consistent way.
+  var edgeObj = edgeArgsToObj(this._isDirected, v, w, name);
+
   v = edgeObj.v;
   w = edgeObj.w;
 
@@ -460,32 +461,37 @@ Graph.prototype.removeEdge = function(v, w, name) {
 };
 
 Graph.prototype.inEdges = function(v, u) {
-  var inV = this._in[v];
-  if (inV) {
-    var edges = _.values(inV);
-    if (!u) {
-      return edges;
-    }
-    return _.filter(edges, function(edge) { return edge.v === u; });
+  if (this.isDirected()) {
+    return this._filterEdges(this._in[v], v, u);
   }
+  return this.nodeEdges(v, u);
 };
 
 Graph.prototype.outEdges = function(v, w) {
-  var outV = this._out[v];
-  if (outV) {
-    var edges = _.values(outV);
-    if (!w) {
-      return edges;
-    }
-    return _.filter(edges, function(edge) { return edge.w === w; });
+  if (this.isDirected()) {
+    return this._filterEdges(this._out[v], v, w);
   }
+  return this.nodeEdges(v, w);
 };
 
 Graph.prototype.nodeEdges = function(v, w) {
-  var inEdges = this.inEdges(v, w);
-  if (inEdges) {
-    return inEdges.concat(this.outEdges(v, w));
+  if (v in this._nodes) {
+    return this._filterEdges(_.merge(this._in[v], this._out[v]), v, w);
+  }
+};
+
+Graph.prototype._filterEdges = function(setV, localEdge, remoteEdge) {
+  if (!setV) {
+    return;
+  }
+  var edges = _.values(setV);
+  if (!remoteEdge) {
+    return edges;
   }
+  return _.filter(edges, function(edge) {
+    return edge.v === localEdge && edge.w === remoteEdge
+        || edge.v === remoteEdge && edge.w === localEdge;
+  });
 };
 
 function incrementOrInitEntry(map, k) {

test/alg/dijkstra-test.js

@@ -44,6 +44,20 @@ describe("alg.dijkstra", function() {
     });
   });
 
+  it("works for undirected graphs when edges have a different natural order",
+    function() {
+      var g = new Graph({ directed: false });
+      g.setPath(["a", "b", "c"]);
+      g.setEdge("b", "d");
+      expect(dijkstra(g, "d")).to.eql({
+        a: { distance: 2, predecessor: "b" },
+        b: { distance: 1, predecessor: "d" },
+        c: { distance: 2, predecessor: "b" },
+        d: { distance: 0 }
+      });
+    }
+  );
+
   it("uses an optionally supplied weight function", function() {
     var g = new Graph();
     g.setEdge("a", "b", 1);