Class Tree.
Inheritance: Graph
示例#1
0
        /// <summary>Builds a tree.</summary>
        /// <param name="x">The Matrix to process.</param>
        /// <param name="y">The Vector to process.</param>
        /// <param name="depth">The depth.</param>
        /// <param name="used">The used.</param>
        /// <returns>A Node.</returns>
        private Node BuildTree(Matrix x, Vector y, int depth, List<int> used, Tree tree)
        {
            if (depth < 0)
                return BuildLeafNode(y.Mode());

            var tuple = GetBestSplit(x, y, used);
            var col = tuple.Item1;
            var gain = tuple.Item2;
            var measure = tuple.Item3;

            // uh oh, need to return something?
            // a weird node of some sort...
            // but just in case...
            if (col == -1)
                return BuildLeafNode(y.Mode());

            used.Add(col);

            Node node = new Node
            {
                Column = col,
                Gain = gain,
                IsLeaf = false,
                Name = Descriptor.ColumnAt(col)
            };

            // populate edges
            List<Edge> edges = new List<Edge>(measure.Segments.Length);
            for (int i = 0; i < measure.Segments.Length; i++)
            {
                // working set
                var segment = measure.Segments[i];
                var edge = new Edge()
                {
                    ParentId = node.Id,
                    Discrete = measure.Discrete,
                    Min = segment.Min,
                    Max = segment.Max
                };

                IEnumerable<int> slice;

                if (edge.Discrete)
                {
                    // get discrete label
                    edge.Label = Descriptor.At(col).Convert(segment.Min).ToString();
                    // do value check for matrix slicing
                    slice = x.Indices(v => v[col] == segment.Min);
                }
                else
                {
                    // get range label
                    edge.Label = string.Format("{0} <= x < {1}", segment.Min, segment.Max);
                    // do range check for matrix slicing
                    slice = x.Indices(v => v[col] >= segment.Min && v[col] < segment.Max);
                }

                // something to look at?
                // if this number is 0 then this edge
                // leads to a dead end - the edge will
                // not be built
                if (slice.Count() > 0)
                {
                    Vector ySlice = y.Slice(slice);
                    // only one answer, set leaf
                    if (ySlice.Distinct().Count() == 1)
                    {
                        var child = BuildLeafNode(ySlice[0]);
                        tree.AddVertex(child);
                        edge.ChildId = child.Id;
                    }
                    // otherwise continue to build tree
                    else
                    {
                        var child = BuildTree(x.Slice(slice), ySlice, depth - 1, used, tree);
                        tree.AddVertex(child);
                        edge.ChildId = child.Id;
                    }

                    edges.Add(edge);
                }
            }

            // problem, need to convert
            // parent to terminal node
            // with mode
            if (edges.Count <= 1)
            {
                var val = y.Mode();
                node.IsLeaf = true;
                node.Value = val;
            }

            tree.AddVertex(node);

            if(edges.Count > 1)
                foreach (var e in edges)
                    tree.AddEdge(e);

            return node;
        }
示例#2
0
        public void TreeNotEqualTest()
        {
            Vertex.Reset();
            Tree g1 = new Tree();
            var r1 = new Vertex();
            g1.Root = r1;
            g1.AddVertex(r1); // 1
            g1.AddVertex(new Vertex()); // 2
            g1.AddVertex(new Vertex()); // 3
            g1.AddVertex(new Vertex()); // 4
            g1.AddVertex(new Vertex()); // 5
            g1.AddVertex(new Vertex()); // 6
            g1.AddVertex(new Vertex()); // 7

            g1.AddEdge(new Edge { ParentId = 1, ChildId = 2 });
            g1.AddEdge(new Edge { ParentId = 1, ChildId = 3 });
            g1.AddEdge(new Edge { ParentId = 2, ChildId = 4 });
            g1.AddEdge(new Edge { ParentId = 2, ChildId = 5 });
            g1.AddEdge(new Edge { ParentId = 3, ChildId = 6 });
            g1.AddEdge(new Edge { ParentId = 3, ChildId = 7 });

            Vertex.Reset();
            Tree g2 = new Tree();
            var r2 = new Vertex();
            g2.Root = r2;
            g2.AddVertex(r2); // 1
            g2.AddVertex(new Vertex()); // 2
            g2.AddVertex(new Vertex()); // 3
            g2.AddVertex(new Vertex()); // 4
            g2.AddVertex(new Vertex()); // 5
            g2.AddVertex(new Vertex()); // 6
            g2.AddVertex(new Vertex()); // 7

            g2.AddEdge(new Edge { ParentId = 1, ChildId = 2 });
            g2.AddEdge(new Edge { ParentId = 1, ChildId = 3 });
            g2.AddEdge(new Edge { ParentId = 2, ChildId = 4 });
            g2.AddEdge(new Edge { ParentId = 2, ChildId = 5 });
            g2.AddEdge(new Edge { ParentId = 1, ChildId = 6 });
            g2.AddEdge(new Edge { ParentId = 3, ChildId = 7 });

            Assert.False(g1.Equals(g2));
        }
示例#3
0
        /// <summary>Generates.</summary>
        /// <exception cref="InvalidOperationException">Thrown when the requested operation is invalid.</exception>
        /// <param name="X">The Matrix to process.</param>
        /// <param name="y">The Vector to process.</param>
        /// <returns>An IModel.</returns>
        public override IModel Generate(Matrix X, Vector y)
        {
            if (Descriptor == null)
                throw new InvalidOperationException("Cannot build decision tree without type knowledge!");

            this.Preprocess(X);

            var tree = new Tree();
            //var n = BuildUglyTree(x, y, Depth, new List<int>(x.Cols));
            tree.Root = BuildTree(X, y, Depth, new List<int>(X.Cols), tree);

            // have to guess something....
            // especially when automating
            // the thing in a Learner
            // this only happens if it is something
            // it has never seen.
            if (Hint == double.Epsilon)
                Hint = y.GetRandom(); // flip a coin...

            return new DecisionTreeModel
            {
                Descriptor = Descriptor,
                NormalizeFeatures = NormalizeFeatures,
                FeatureNormalizer = FeatureNormalizer,
                FeatureProperties = FeatureProperties,
                Tree = tree,
                Hint = Hint
            };
        }