Added method removeEdge.

Author: simphotonics

CHANGELOG.md

@@ -1,5 +1,8 @@
+## 0.5.5
+- Added [`DirectedGraph`][DirectedGraph], [`WeightedDirectedGraph`][WeightedDirectedGraph] method `removeEdge`.
+
 ## 0.5.4
-- Fixed documentation of the graph method `clear`. This method removes all graph
+- Fixed the documentation of the graph method `clear`. This method removes all graph
 vertices. The resulting graph will be empty.
 - Added the graph method `clearEdges`. This method removes only the graph
 edges, leaving the graph vertices in place.

lib/src/graph/directed_graph.dart

@@ -114,8 +114,14 @@ class DirectedGraph<T extends Object> extends DirectedGraphBase<T> {
     updateCache();
   }
 
+  /// Removes the edge pointing from [vertex] to [connectedVertex].
+  /// Does not remove the vertices.
+  void removeEdge(T vertex, T connectedVertex) {
+    _edges[vertex]?.remove(connectedVertex);
+  }
+
   /// Removes edges (connections) pointing from [vertex] to [connectedVertices].
-  /// * Note: Does not remove the vertices.
+  /// Note: Does not remove the vertices.
   void removeEdges(T vertex, Set<T> connectedVertices) {
     _edges[vertex]?.removeAll(connectedVertices);
     updateCache();

lib/src/graph/weighted_directed_graph.dart

@@ -172,6 +172,12 @@ class WeightedDirectedGraph<T extends Object, W extends Comparable>
     updateCache();
   }
 
+  /// Removes the edge pointing from [vertex] to [connectedVertex].
+  /// Does not remove the vertices.
+  void removeEdge(T vertex, T connectedVertex) {
+    _edges[vertex]?.remove(connectedVertex);
+  }
+
   /// Removes edges pointing from [vertex] to [connectedVertices].
   ///
   /// Does not remove any vertices from the graph.

pubspec.yaml

@@ -3,7 +3,7 @@ name: directed_graph
 description: Generic directed graph and weighted directed graph with algorithms
   enabling sorting and topological ordering of vertices.
 
-version: 0.5.4
+version: 0.5.5
 
 homepage: https://github.com/simphotonics/directed_graph
 

test/directed_graph_test.dart

@@ -93,40 +93,44 @@ void main() {
     });
   });
 
-  group('Manipulating edges/vertices.', () {
-    test('addEdges():', () {
+  group('Manipulating edges/vertices:', () {
+    test('addEdge', () {
+      final graph = DirectedGraph.of(graph0);
+      graph.addEdge(i, k);
+      expect(graph.edges(i), {l, k});
+    });
+
+    test('addEdges', () {
       final graph = DirectedGraph.of(graph0);
       graph.addEdges(i, {k});
       expect(graph.edges(i), {l, k});
-      '{\n'
-          ' a: [b, h, c, e],\n'
-          ' b: [h],\n'
-          ' c: [h, g],\n'
-          ' d: [e, f],\n'
-          ' e: [],\n'
-          ' f: [i],\n'
-          ' g: [],\n'
-          ' h: [],\n'
-          ' i: {l},\n'
-          ' k: [g, f],\n'
-          ' l: [],\n'
-          '}';
-    });
-    test('remove(l).', () {
+    });
+    test('removeEdge', () {
+      final graph = DirectedGraph.of(graph0);
+      graph.removeEdge(a, b);
+      expect(graph.edges(a), {h, c, e});
+    });
+    test('removeEdges', () {
+      final graph = DirectedGraph.of(graph0);
+      graph.removeEdges(a, {b, h, c});
+      expect(graph.edges(a), {e});
+    });
+
+    test('remove(l)', () {
       final graph = DirectedGraph.of(graph0);
       graph.remove(l);
       expect(graph.edges(i), <String>{});
       expect(graph.sortedVertices.toList(), [
-        'a',
-        'b',
-        'c',
-        'd',
-        'e',
-        'f',
-        'g',
-        'h',
-        'i',
-        'k',
+        a,
+        b,
+        c,
+        d,
+        e,
+        f,
+        g,
+        h,
+        i,
+        k,
       ]);
     });
     test('clear', () {
@@ -429,17 +433,17 @@ void main() {
         vertex = '${vertex}1';
       }
       expect(graph.sortedVertices, {
-        'a',
-        'b',
-        'c',
-        'd',
-        'e',
-        'f',
-        'g',
-        'h',
-        'i',
-        'k',
-        'l',
+        a,
+        b,
+        c,
+        d,
+        e,
+        f,
+        g,
+        h,
+        i,
+        k,
+        l,
       });
     });
   });

test/weighted_directed_graph_test.dart

@@ -96,12 +96,30 @@ void main() {
       expect(graph.vertices.contains(l), false);
       // Restore graph:
     });
+    test('addEdge', () {
+      final graph = WeightedDirectedGraph.of(graph0);
+      graph.addEdge(g, h, 1);
+      expect(graph.edges(g), {h});
+      expect(graph.weightAlong([g, h]), 1);
+    });
+
     test('addEdges(\'g\',{\'h\': 1}):', () {
       final graph = WeightedDirectedGraph.of(graph0);
-      graph.addEdges('g', {'h': 1});
-      expect(graph.edges('g'), {'h'});
-      expect(graph.data['g']?['h'], 1);
+      graph.addEdges(g, {h: 1});
+      expect(graph.edges(g), {h});
+      expect(graph.weightAlong([g, h]), 1);
+    });
+    test('removeEdge', () {
+      final graph = WeightedDirectedGraph.of(graph0);
+      graph.removeEdge(a, b);
+      expect(graph.edges(a), {h, c, e});
+    });
+    test('removeEdges', () {
+      final graph = WeightedDirectedGraph.of(graph0);
+      graph.removeEdges(a, {b, h, c});
+      expect(graph.edges(a), {e});
     });
+
     test('clear', () {
       final graph = WeightedDirectedGraph.of(graph0);
       expect(graph.sortedVertices, graph0.sortedVertices);
@@ -301,17 +319,17 @@ void main() {
       expect(
         WeightedDirectedGraph.transitiveClosure(graph).data,
         <String, Map<String, int>>{
-          'a': {'b': 1, 'h': 7, 'c': 2, 'g': 6, 'e': 4},
-          'b': {'h': 6},
-          'c': {'h': 5, 'g': 4},
-          'd': {'e': 1, 'g': 3, 'f': 2, 'i': 5, 'l': 8},
-          'e': {'g': 2},
-          'f': {'i': 3, 'l': 6},
-          'g': {},
-          'h': {},
-          'i': {'l': 3},
-          'k': {'g': 4, 'f': 5, 'i': 8, 'l': 11},
-          'l': {},
+          a: {b: 1, h: 7, c: 2, g: 6, e: 4},
+          b: {h: 6},
+          c: {h: 5, g: 4},
+          d: {e: 1, g: 3, f: 2, i: 5, l: 8},
+          e: {g: 2},
+          f: {i: 3, l: 6},
+          g: {},
+          h: {},
+          i: {l: 3},
+          k: {g: 4, f: 5, i: 8, l: 11},
+          l: {},
         },
       );
     });
@@ -320,7 +338,7 @@ void main() {
   group('path:', () {
     test('min. weight', () {
       final graph = WeightedDirectedGraph.of(graph0);
-      expect(graph.lightestPath('a', 'g'), [a, c, g]);
+      expect(graph.lightestPath(a, g), [a, c, g]);
       expect(graph.weightAlong([a, c, g]), 6);
     });
     test('max. weight', () {
@@ -351,17 +369,17 @@ void main() {
         vertex = '${vertex}1';
       }
       expect(graph.sortedVertices, {
-        'a',
-        'b',
-        'c',
-        'd',
-        'e',
-        'f',
-        'g',
-        'h',
-        'i',
-        'k',
-        'l',
+        a,
+        b,
+        c,
+        d,
+        e,
+        f,
+        g,
+        h,
+        i,
+        k,
+        l,
       });
     });
   });