Merge branch 'performance' into 'master'

Fix: Cache ColorsUsed for huge performance boost

See merge request !39

src/SparseTransform/Convert/ColoredDotWriter.cs

@@ -8,17 +8,20 @@ namespace SparseTransform.Convert
     /// </summary>
     public class ColoredDotWriter : DotWriter
     {
-        private IGraph _coloredGraph;
         private bool _textcolor;
-       
+        private int _colorsUsed;
+        private int _hueFactor;
+
         /// <summary>
         /// Constructor constructing a color-dictionary for coloring purpose.
         /// </summary>
         /// <param name="textColor">decision whether the labels should be colored or labelled.</param>
         public ColoredDotWriter(IGraph graph, bool textColor)
         {
-            this._coloredGraph = graph;
+            this._colorsUsed = graph.ColorsUsed;
             this._textcolor = textColor;
+            // This is the offset for coloring. Less colors = more distance between. Cached for NodeLabel.
+            this._hueFactor = 255 / this._colorsUsed;
         }
        
         /// <summary>
@@ -29,10 +32,8 @@ namespace SparseTransform.Convert
         /// <returns></returns>
         public override String NodeLabel(GraphNode node, String prefix)
         {
-            // This is the offset. Less colors = more distance between
-            int hueFactor = 255 / _coloredGraph.ColorsUsed;
             // Calculate the hue. We modulo with 255 to not exceed spectrum. Then convert to float for DOT
-            double hue = Math.Round((double)((node.Color * hueFactor) % 255) / 255, 3);
+            double hue = Math.Round((double)((node.Color * _hueFactor) % 255) / 255, 3);
 
             StringBuilder label = new StringBuilder();
             // Append label name and general layout info
@@ -41,7 +42,7 @@ namespace SparseTransform.Convert
             // If current node is colored, apply either text label with color or set fill color
             if (node.Colored)
             {
-                if (_textcolor || _coloredGraph.ColorsUsed > 255)
+                if (_textcolor || this._colorsUsed > 255)
                 {
                     label.Append($", label=\"{prefix}{node.Index}\\n color:{node.Color}\"");
                 }

src/SparseTransform/DataStructures/AdjacencyGraph.cs

@@ -45,6 +45,7 @@ namespace SparseTransform.DataStructures
             }
         }
 
+        private int _colorsUsed = 0;
         /// <summary>
         /// Number of colors used for coloring.
         /// </summary>
@@ -52,20 +53,24 @@ namespace SparseTransform.DataStructures
         {
             get
             {
-                List<int> colors = new List<int>();
-                if (Colored)
+                if (this._colorsUsed == 0)
                 {
-                    foreach (GraphNode node in _nodes)
+                    List<int> colors = new List<int>();
+                    if (Colored)
                     {
-                        int color = node.Color;
-                        // Do not check for != 0 since we already know everything here is colored
-                        if (!colors.Contains(color))
+                        foreach (GraphNode node in _nodes)
                         {
-                            colors.Add(color);
+                            int color = node.Color;
+                            // Do not check for != 0 since we already know everything here is colored
+                            if (!colors.Contains(color))
+                            {
+                                colors.Add(color);
+                            }
                         }
                     }
+                    this._colorsUsed = colors.Count;
                 }
-                return colors.Count;
+                return this._colorsUsed;
             }
         }
 
@@ -79,7 +84,7 @@ namespace SparseTransform.DataStructures
 
         public void AddEdge(int i, int j)
         {
-            if(i != j)
+            if (i != j)
             {
                 GraphNode iNode = AddNode(i);
                 GraphNode jNode = AddNode(j);

src/SparseTransform/DataStructures/BipartiteGraph.cs

@@ -88,6 +88,7 @@ namespace SparseTransform.DataStructures
             }
         }
 
+        private int _colorsUsed = 0;
         /// <summary>
         /// Number of colors used for coloring. Works if either or both sides are colored
         /// </summary>
@@ -95,32 +96,38 @@ namespace SparseTransform.DataStructures
         {
             get
             {
-                List<int> colors = new List<int>();
-                if (LeftColored)
+                if (_colorsUsed == 0)
                 {
-                    foreach (GraphNode node in _leftNodes)
+                    List<int> colors = new List<int>();
+                    if (LeftColored)
                     {
-                        int color = node.Color;
-                        // Do not check for != 0 since we already know everything here is colored
-                        if (!colors.Contains(color))
+                        foreach (GraphNode node in _leftNodes)
                         {
-                            colors.Add(color);
+                            int color = node.Color;
+                            // Do not check for != 0 since we already know everything here is colored
+                            if (!colors.Contains(color))
+                            {
+                                colors.Add(color);
+                            }
                         }
                     }
-                }
-                if (RightColored)
-                {
-                    foreach (GraphNode node in _rightNodes)
+                    if (RightColored)
                     {
-                        int color = node.Color;
-                        // Do not check for != 0 since we already know everything here is colored
-                        if (!colors.Contains(color))
+                        foreach (GraphNode node in _rightNodes)
                         {
-                            colors.Add(color);
+                            int color = node.Color;
+                            // Do not check for != 0 since we already know everything here is colored
+                            if (!colors.Contains(color))
+                            {
+                                colors.Add(color);
+                            }
                         }
                     }
+                    this._colorsUsed = colors.Count;
                 }
-                return colors.Count;
+
+                return _colorsUsed;
+
             }
         }