Added the method clearEdges.

Author: simphotonics

CHANGELOG.md

@@ -1,7 +1,12 @@
+## 0.5.4
+- Fixed documentation of graph method `clear`. This method removes all graph
+vertices.
+- Added the graph method `clearEdges`. This method removes only the graph
+edges, leaving the graph vertice in place. 
 
 ## 0.5.3
 - Added `WeightedDirectedGraph` methods: `weightedEdges` and `updateEdgeWeight`.
-- Updated docs and examples. 
+- Updated docs and examples.
 
 ## 0.5.2
 - Fixed grammar in CHANGELOG entry below.

lib/src/graph/directed_graph.dart

@@ -142,7 +142,15 @@ class DirectedGraph<T extends Object> extends DirectedGraphBase<T> {
     }
   }
 
-  /// Removes all graph edges.
+  @override
+  void clearEdges() {
+    for (final vertex in _edges.keys) {
+      _edges[vertex]!.clear();
+    }
+    updateCache();
+  }
+
+  @override
   void clear() {
     _edges.clear();
     updateCache();

lib/src/graph/directed_graph_base.dart

@@ -30,6 +30,15 @@ abstract class DirectedGraphBase<T extends Object> extends Iterable<T> {
   @override
   bool contains(Object? element);
 
+  /// Removes all graph vertices. After this method returns the graph
+  /// will be empty.
+  void clear();
+
+  /// Removes all graph edges (connections between vertices). The graph vertices
+  /// are not removed. To remove all vertices and (implicitly) all graph edges
+  /// use the method [clear].
+  void clearEdges();
+
   /// Returns the shortest path from the vertex [start] to the vertex [target].
   /// * Returns an empty list if [target] is not reachable from [start].
   List<T> shortestPath(T start, T target) => crawler.path(start, target);

lib/src/graph/weighted_directed_graph.dart

@@ -12,9 +12,9 @@ typedef Summation<W> = W Function(W left, W right);
 int defaultWeightComparator<W extends Comparable>(W left, W right) =>
     left.compareTo(right);
 
-/// A directed graph with vertices of type `T` and a weight of type
-/// `W` associated with each directed edges.
-/// * `T` must be usable as a map key.
+/// A directed graph with vertices of type [T] and a weight of type
+/// [W] associated with each directed edge.
+/// * [T] must be usable as a map key.
 class WeightedDirectedGraph<T extends Object, W extends Comparable>
     extends DirectedGraphBase<T> {
   /// Constructs a weighted directed graph with vertices of type `T`
@@ -206,7 +206,15 @@ class WeightedDirectedGraph<T extends Object, W extends Comparable>
     updateCache();
   }
 
-  /// Removes all graph edges.
+  @override
+  void clearEdges() {
+    for (final vertex in _edges.keys) {
+      _edges[vertex]!.clear();
+    }
+    updateCache();
+  }
+
+  @override
   void clear() {
     _edges.clear();
     updateCache();

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: 0.5.3
+version: 0.5.4
 
 homepage: https://github.com/simphotonics/directed_graph
 

test/directed_graph_test.dart

@@ -135,6 +135,15 @@ void main() {
       graph.clear();
       expect(graph.isEmpty, true);
     });
+    test('clearEdges', () {
+      final graph = DirectedGraph.of(graph0);
+      expect(graph.sortedVertices, graph0.sortedVertices);
+      graph.clearEdges();
+      expect(graph.sortedVertices, graph0.sortedVertices);
+      for (var vertex in graph.sortedVertices) {
+        expect(graph.edges(vertex), isEmpty);
+      }
+    });
   });
   group('Graph data:', () {
     final graph = DirectedGraph.of(graph0);

test/weighted_directed_graph_test.dart

@@ -108,6 +108,15 @@ void main() {
       graph.clear();
       expect(graph.isEmpty, true);
     });
+    test('clearEdges', () {
+      final graph = WeightedDirectedGraph.of(graph0);
+      expect(graph.sortedVertices, graph0.sortedVertices);
+      graph.clearEdges();
+      expect(graph.sortedVertices, graph0.sortedVertices);
+      for (var vertex in graph.sortedVertices) {
+        expect(graph.edges(vertex), isEmpty);
+      }
+    });
   });
   group('Graph data:', () {
     test('edges().', () {