protected void WriteDatasetToExcel(ExcelWorksheet datasetWorksheet, IDataAnalysisProblemData problemData)
{
//remark the performance of EPPlus drops dramatically
//if the data is not written row wise (from left to right) due the internal indices used.
IDataset dataset = problemData.Dataset;
var variableNames = dataset.VariableNames.ToList();
var doubleVariables = new HashSet <string>(dataset.DoubleVariables);
for (int col = 1; col <= variableNames.Count; col++)
{
datasetWorksheet.Cells[1, col].Value = variableNames[col - 1];
}
for (int row = 0; row < dataset.Rows; row++)
{
for (int col = 0; col < variableNames.Count; col++)
{
if (doubleVariables.Contains(variableNames[col]))
{
datasetWorksheet.Cells[row + 2, col + 1].Value = dataset.GetDoubleValue(variableNames[col], row);
}
else
{
datasetWorksheet.Cells[row + 2, col + 1].Value = dataset.GetValue(row, col);
}
}
}
}
public double[,] RevertData(IDataset dataset, IEnumerable <int> rows)
{
var instances = rows.ToArray();
var components = ComponentNames;
var result = new double[instances.Length, VariableNames.Length];
for (var r = 0; r < instances.Length; r++)
{
for (var i = 0; i < components.Length; i++)
{
var val = dataset.GetDoubleValue(components[i], instances[r]);
for (var j = 0; j < VariableNames.Length; j++)
{
result[r, j] += val * Matrix[j, i];
}
}
}
for (var r = 0; r < instances.Length; r++)
{
for (var j = 0; j < VariableNames.Length; j++)
{
result[r, j] *= Deviations[j];
result[r, j] += Means[j];
}
}
return(result);
}
public static IEnumerable<int> FindClosestCenters(IEnumerable<double[]> centers, IDataset dataset, IEnumerable<string> allowedInputVariables, IEnumerable<int> rows) {
int nRows = rows.Count();
int nCols = allowedInputVariables.Count();
int[] closestCenter = new int[nRows];
double[] bestCenterDistance = Enumerable.Repeat(double.MaxValue, nRows).ToArray();
int centerIndex = 1;
foreach (double[] center in centers) {
if (nCols != center.Length) throw new ArgumentException();
int rowIndex = 0;
foreach (var row in rows) {
// calc euclidian distance of point to center
double centerDistance = 0;
int col = 0;
foreach (var inputVariable in allowedInputVariables) {
double d = center[col++] - dataset.GetDoubleValue(inputVariable, row);
d = d * d; // square;
centerDistance += d;
if (centerDistance > bestCenterDistance[rowIndex]) break;
}
if (centerDistance < bestCenterDistance[rowIndex]) {
bestCenterDistance[rowIndex] = centerDistance;
closestCenter[rowIndex] = centerIndex;
}
rowIndex++;
}
centerIndex++;
}
return closestCenter;
}
private double GetEstimatedValue(IDataset dataset, int row)
{
if (!IsLeaf)
{
return((dataset.GetDoubleValue(SplitAttribute, row) <= SplitValue ? Left : Right).GetEstimatedValue(dataset, row));
}
if (Model == null)
{
throw new NotSupportedException("The model has not been built correctly");
}
return(Model.GetEstimatedValues(dataset, new[] { row }).First());
}
public static double CalculateIntraClusterSumOfSquares(KMeansClusteringModel model, IDataset dataset, IEnumerable<int> rows) {
List<int> clusterValues = model.GetClusterValues(dataset, rows).ToList();
List<string> allowedInputVariables = model.AllowedInputVariables.ToList();
int nCols = allowedInputVariables.Count;
Dictionary<int, List<double[]>> clusterPoints = new Dictionary<int, List<double[]>>();
Dictionary<int, double[]> clusterMeans = new Dictionary<int, double[]>();
foreach (var clusterValue in clusterValues.Distinct()) {
clusterPoints.Add(clusterValue, new List<double[]>());
}
// collect points of clusters
int clusterValueIndex = 0;
foreach (var row in rows) {
double[] p = new double[allowedInputVariables.Count];
for (int i = 0; i < nCols; i++) {
p[i] = dataset.GetDoubleValue(allowedInputVariables[i], row);
}
clusterPoints[clusterValues[clusterValueIndex++]].Add(p);
}
// calculate cluster means
foreach (var pair in clusterPoints) {
double[] mean = new double[nCols];
foreach (var p in pair.Value) {
for (int i = 0; i < nCols; i++) {
mean[i] += p[i];
}
}
for (int i = 0; i < nCols; i++) {
mean[i] /= pair.Value.Count;
}
clusterMeans[pair.Key] = mean;
}
// calculate distances
double allCenterDistances = 0;
foreach (var pair in clusterMeans) {
double[] mean = pair.Value;
double centerDistances = 0;
foreach (var clusterPoint in clusterPoints[pair.Key]) {
double centerDistance = 0;
for (int i = 0; i < nCols; i++) {
double d = mean[i] - clusterPoint[i];
d = d * d;
centerDistance += d;
}
centerDistances += centerDistance;
}
allCenterDistances += centerDistances;
}
return allCenterDistances;
}
/// <summary>
/// Transforms <paramref name="dataset"/> into a data structure as needed by libSVM.
/// </summary>
/// <param name="dataset">The source dataset</param>
/// <param name="targetVariable">The target variable</param>
/// <param name="inputVariables">The selected input variables to include in the svm_problem.</param>
/// <param name="rowIndices">The rows of the dataset that should be contained in the resulting SVM-problem</param>
/// <returns>A problem data type that can be used to train a support vector machine.</returns>
public static svm_problem CreateSvmProblem(IDataset dataset, string targetVariable, IEnumerable <string> inputVariables, IEnumerable <int> rowIndices)
{
double[] targetVector;
var nRows = rowIndices.Count();
if (string.IsNullOrEmpty(targetVariable))
{
// if the target variable is not set (e.g. for prediction of a trained model) we just use a zero vector
targetVector = new double[nRows];
}
else
{
targetVector = dataset.GetDoubleValues(targetVariable, rowIndices).ToArray();
}
svm_node[][] nodes = new svm_node[nRows][];
int maxNodeIndex = 0;
int svmProblemRowIndex = 0;
List <string> inputVariablesList = inputVariables.ToList();
foreach (int row in rowIndices)
{
List <svm_node> tempRow = new List <svm_node>();
int colIndex = 1; // make sure the smallest node index for SVM = 1
foreach (var inputVariable in inputVariablesList)
{
double value = dataset.GetDoubleValue(inputVariable, row);
// SVM also works with missing values
// => don't add NaN values in the dataset to the sparse SVM matrix representation
if (!double.IsNaN(value))
{
tempRow.Add(new svm_node()
{
index = colIndex, value = value
});
// nodes must be sorted in ascending ordered by column index
if (colIndex > maxNodeIndex)
{
maxNodeIndex = colIndex;
}
}
colIndex++;
}
nodes[svmProblemRowIndex++] = tempRow.ToArray();
}
return(new svm_problem {
l = targetVector.Length, y = targetVector, x = nodes
});
}
public double[,] TransformData(IDataset dataset, IEnumerable <int> rows)
{
var instances = rows.ToArray();
var result = new double[instances.Length, VariableNames.Length];
for (var r = 0; r < instances.Length; r++)
{
for (var i = 0; i < VariableNames.Length; i++)
{
var val = (dataset.GetDoubleValue(VariableNames[i], instances[r]) - Means[i]) / Deviations[i];
for (var j = 0; j < VariableNames.Length; j++)
{
result[r, j] += val * Matrix[i, j];
}
}
}
return(result);
}
private static double[,] PCAReduce(IDataset dataset, IEnumerable <int> rows, IEnumerable <string> variables)
{
var instances = rows.ToArray();
var attributes = variables.ToArray();
var data = new double[instances.Length, attributes.Length + 1];
for (int j = 0; j < attributes.Length; j++)
{
int i = 0;
var values = dataset.GetDoubleValues(attributes[j], instances);
foreach (var v in values)
{
data[i++, j] = v;
}
}
int info;
double[] variances;
var matrix = new double[0, 0];
alglib.pcabuildbasis(data, instances.Length, attributes.Length, out info, out variances, out matrix);
var result = new double[instances.Length, matrix.GetLength(1)];
int r = 0;
foreach (var inst in instances)
{
int i = 0;
foreach (var attrib in attributes)
{
double val = dataset.GetDoubleValue(attrib, inst);
for (int j = 0; j < result.GetLength(1); j++)
{
result[r, j] += val * matrix[i, j];
}
i++;
}
r++;
}
return(result);
}
public static IEnumerable <int> FindClosestCenters(IEnumerable <double[]> centers, IDataset dataset, IEnumerable <string> allowedInputVariables, IEnumerable <int> rows)
{
int nRows = rows.Count();
int nCols = allowedInputVariables.Count();
int[] closestCenter = new int[nRows];
double[] bestCenterDistance = Enumerable.Repeat(double.MaxValue, nRows).ToArray();
int centerIndex = 1;
foreach (double[] center in centers)
{
if (nCols != center.Length)
{
throw new ArgumentException();
}
int rowIndex = 0;
foreach (var row in rows)
{
// calc euclidian distance of point to center
double centerDistance = 0;
int col = 0;
foreach (var inputVariable in allowedInputVariables)
{
double d = center[col++] - dataset.GetDoubleValue(inputVariable, row);
d = d * d; // square;
centerDistance += d;
if (centerDistance > bestCenterDistance[rowIndex])
{
break;
}
}
if (centerDistance < bestCenterDistance[rowIndex])
{
bestCenterDistance[rowIndex] = centerDistance;
closestCenter[rowIndex] = centerIndex;
}
rowIndex++;
}
centerIndex++;
}
return(closestCenter);
}
private void EvaluateLaggedOperations(ISymbolicDataAnalysisExpressionTreeInterpreter interpreter, IDataset ds)
{
// lag
Evaluate(interpreter, ds, "(lagVariable 1.0 a -1) ", 1, ds.GetDoubleValue("A", 0));
Evaluate(interpreter, ds, "(lagVariable 1.0 a -1) ", 2, ds.GetDoubleValue("A", 1));
Evaluate(interpreter, ds, "(lagVariable 1.0 a 0) ", 2, ds.GetDoubleValue("A", 2));
Evaluate(interpreter, ds, "(lagVariable 1.0 a 1) ", 0, ds.GetDoubleValue("A", 1));
// integral
Evaluate(interpreter, ds, "(integral -1.0 (variable 1.0 a)) ", 1, ds.GetDoubleValue("A", 0) + ds.GetDoubleValue("A", 1));
Evaluate(interpreter, ds, "(integral -1.0 (lagVariable 1.0 a 1)) ", 1, ds.GetDoubleValue("A", 1) + ds.GetDoubleValue("A", 2));
Evaluate(interpreter, ds, "(integral -2.0 (variable 1.0 a)) ", 2, ds.GetDoubleValue("A", 0) + ds.GetDoubleValue("A", 1) + ds.GetDoubleValue("A", 2));
Evaluate(interpreter, ds, "(integral -1.0 (* (variable 1.0 a) (variable 1.0 b)))", 1, ds.GetDoubleValue("A", 0) * ds.GetDoubleValue("B", 0) + ds.GetDoubleValue("A", 1) * ds.GetDoubleValue("B", 1));
Evaluate(interpreter, ds, "(integral -2.0 3.0)", 1, 9.0);
// derivative
// (f_0 + 2 * f_1 - 2 * f_3 - f_4) / 8; // h = 1
Evaluate(interpreter, ds, "(diff (variable 1.0 a)) ", 5, (ds.GetDoubleValue("A", 5) + 2 * ds.GetDoubleValue("A", 4) - 2 * ds.GetDoubleValue("A", 2) - ds.GetDoubleValue("A", 1)) / 8.0);
Evaluate(interpreter, ds, "(diff (variable 1.0 b)) ", 5, (ds.GetDoubleValue("B", 5) + 2 * ds.GetDoubleValue("B", 4) - 2 * ds.GetDoubleValue("B", 2) - ds.GetDoubleValue("B", 1)) / 8.0);
Evaluate(interpreter, ds, "(diff (* (variable 1.0 a) (variable 1.0 b)))", 5, +
(ds.GetDoubleValue("A", 5) * ds.GetDoubleValue("B", 5) +
2 * ds.GetDoubleValue("A", 4) * ds.GetDoubleValue("B", 4) -
2 * ds.GetDoubleValue("A", 2) * ds.GetDoubleValue("B", 2) -
ds.GetDoubleValue("A", 1) * ds.GetDoubleValue("B", 1)) / 8.0);
Evaluate(interpreter, ds, "(diff -2.0 3.0)", 5, 0.0);
// timelag
Evaluate(interpreter, ds, "(lag -1.0 (lagVariable 1.0 a 2)) ", 1, ds.GetDoubleValue("A", 2));
Evaluate(interpreter, ds, "(lag -2.0 (lagVariable 1.0 a 2)) ", 2, ds.GetDoubleValue("A", 2));
Evaluate(interpreter, ds, "(lag -1.0 (* (lagVariable 1.0 a 1) (lagVariable 1.0 b 2)))", 1, ds.GetDoubleValue("A", 1) * ds.GetDoubleValue("B", 2));
Evaluate(interpreter, ds, "(lag -2.0 3.0)", 1, 3.0);
}
public static double OptimizeConstants(ISymbolicDataAnalysisExpressionTreeInterpreter interpreter,
ISymbolicExpressionTree tree, IRegressionProblemData problemData, IEnumerable <int> rows, bool applyLinearScaling,
int maxIterations, bool updateVariableWeights = true,
double lowerEstimationLimit = double.MinValue, double upperEstimationLimit = double.MaxValue,
bool updateConstantsInTree = true, Action <double[], double, object> iterationCallback = null, EvaluationsCounter counter = null)
{
// numeric constants in the tree become variables for constant opt
// variables in the tree become parameters (fixed values) for constant opt
// for each parameter (variable in the original tree) we store the
// variable name, variable value (for factor vars) and lag as a DataForVariable object.
// A dictionary is used to find parameters
double[] initialConstants;
var parameters = new List <TreeToAutoDiffTermConverter.DataForVariable>();
TreeToAutoDiffTermConverter.ParametricFunction func;
TreeToAutoDiffTermConverter.ParametricFunctionGradient func_grad;
if (!TreeToAutoDiffTermConverter.TryConvertToAutoDiff(tree, updateVariableWeights, applyLinearScaling, out parameters, out initialConstants, out func, out func_grad))
{
throw new NotSupportedException("Could not optimize constants of symbolic expression tree due to not supported symbols used in the tree.");
}
if (parameters.Count == 0)
{
return(0.0); // gkronber: constant expressions always have a R² of 0.0
}
var parameterEntries = parameters.ToArray(); // order of entries must be the same for x
//extract inital constants
double[] c;
if (applyLinearScaling)
{
c = new double[initialConstants.Length + 2];
c[0] = 0.0;
c[1] = 1.0;
Array.Copy(initialConstants, 0, c, 2, initialConstants.Length);
}
else
{
c = (double[])initialConstants.Clone();
}
double originalQuality = SymbolicRegressionSingleObjectivePearsonRSquaredEvaluator.Calculate(interpreter, tree, lowerEstimationLimit, upperEstimationLimit, problemData, rows, applyLinearScaling);
if (counter == null)
{
counter = new EvaluationsCounter();
}
var rowEvaluationsCounter = new EvaluationsCounter();
alglib.lsfitstate state;
alglib.lsfitreport rep;
int retVal;
IDataset ds = problemData.Dataset;
double[,] x = new double[rows.Count(), parameters.Count];
int row = 0;
foreach (var r in rows)
{
int col = 0;
foreach (var info in parameterEntries)
{
if (ds.VariableHasType <double>(info.variableName))
{
x[row, col] = ds.GetDoubleValue(info.variableName, r + info.lag);
}
else if (ds.VariableHasType <string>(info.variableName))
{
x[row, col] = ds.GetStringValue(info.variableName, r) == info.variableValue ? 1 : 0;
}
else
{
throw new InvalidProgramException("found a variable of unknown type");
}
col++;
}
row++;
}
double[] y = ds.GetDoubleValues(problemData.TargetVariable, rows).ToArray();
int n = x.GetLength(0);
int m = x.GetLength(1);
int k = c.Length;
alglib.ndimensional_pfunc function_cx_1_func = CreatePFunc(func);
alglib.ndimensional_pgrad function_cx_1_grad = CreatePGrad(func_grad);
alglib.ndimensional_rep xrep = (p, f, obj) => iterationCallback(p, f, obj);
try {
alglib.lsfitcreatefg(x, y, c, n, m, k, false, out state);
alglib.lsfitsetcond(state, 0.0, 0.0, maxIterations);
alglib.lsfitsetxrep(state, iterationCallback != null);
//alglib.lsfitsetgradientcheck(state, 0.001);
alglib.lsfitfit(state, function_cx_1_func, function_cx_1_grad, xrep, rowEvaluationsCounter);
alglib.lsfitresults(state, out retVal, out c, out rep);
} catch (ArithmeticException) {
return(originalQuality);
} catch (alglib.alglibexception) {
return(originalQuality);
}
counter.FunctionEvaluations += rowEvaluationsCounter.FunctionEvaluations / n;
counter.GradientEvaluations += rowEvaluationsCounter.GradientEvaluations / n;
//retVal == -7 => constant optimization failed due to wrong gradient
if (retVal != -7)
{
if (applyLinearScaling)
{
var tmp = new double[c.Length - 2];
Array.Copy(c, 2, tmp, 0, tmp.Length);
UpdateConstants(tree, tmp, updateVariableWeights);
}
else
{
UpdateConstants(tree, c, updateVariableWeights);
}
}
var quality = SymbolicRegressionSingleObjectivePearsonRSquaredEvaluator.Calculate(interpreter, tree, lowerEstimationLimit, upperEstimationLimit, problemData, rows, applyLinearScaling);
if (!updateConstantsInTree)
{
UpdateConstants(tree, initialConstants, updateVariableWeights);
}
if (originalQuality - quality > 0.001 || double.IsNaN(quality))
{
UpdateConstants(tree, initialConstants, updateVariableWeights);
return(originalQuality);
}
return(quality);
}
private double GetEstimatedVariance(IDataset dataset, int row)
{
return(!IsLeaf ? ((IConfidenceRegressionModel)(dataset.GetDoubleValue(SplitAttribute, row) <= SplitValue ? Left : Right)).GetEstimatedVariances(dataset, row.ToEnumerable()).Single() : ((IConfidenceRegressionModel)Model).GetEstimatedVariances(dataset, new[] { row }).First());
}
public static double CalculateIntraClusterSumOfSquares(KMeansClusteringModel model, IDataset dataset, IEnumerable <int> rows)
{
List <int> clusterValues = model.GetClusterValues(dataset, rows).ToList();
List <string> allowedInputVariables = model.AllowedInputVariables.ToList();
int nCols = allowedInputVariables.Count;
Dictionary <int, List <double[]> > clusterPoints = new Dictionary <int, List <double[]> >();
Dictionary <int, double[]> clusterMeans = new Dictionary <int, double[]>();
foreach (var clusterValue in clusterValues.Distinct())
{
clusterPoints.Add(clusterValue, new List <double[]>());
}
// collect points of clusters
int clusterValueIndex = 0;
foreach (var row in rows)
{
double[] p = new double[allowedInputVariables.Count];
for (int i = 0; i < nCols; i++)
{
p[i] = dataset.GetDoubleValue(allowedInputVariables[i], row);
}
clusterPoints[clusterValues[clusterValueIndex++]].Add(p);
}
// calculate cluster means
foreach (var pair in clusterPoints)
{
double[] mean = new double[nCols];
foreach (var p in pair.Value)
{
for (int i = 0; i < nCols; i++)
{
mean[i] += p[i];
}
}
for (int i = 0; i < nCols; i++)
{
mean[i] /= pair.Value.Count;
}
clusterMeans[pair.Key] = mean;
}
// calculate distances
double allCenterDistances = 0;
foreach (var pair in clusterMeans)
{
double[] mean = pair.Value;
double centerDistances = 0;
foreach (var clusterPoint in clusterPoints[pair.Key])
{
double centerDistance = 0;
for (int i = 0; i < nCols; i++)
{
double d = mean[i] - clusterPoint[i];
d = d * d;
centerDistance += d;
}
centerDistances += centerDistance;
}
allCenterDistances += centerDistances;
}
return(allCenterDistances);
}
private double GetEstimatedValue(IDataset dataset, int row)
{
return(Intercept + (Coefficients.Count == 0 ? 0 : Coefficients.Sum(s => s.Value * dataset.GetDoubleValue(s.Key, row))));
}
public static double OptimizeConstants(ISymbolicDataAnalysisExpressionTreeInterpreter interpreter, ISymbolicExpressionTree tree, IRegressionProblemData problemData, IEnumerable <int> rows, bool applyLinearScaling, int maxIterations, bool updateVariableWeights = true, double lowerEstimationLimit = double.MinValue, double upperEstimationLimit = double.MaxValue, bool updateConstantsInTree = true)
{
List <AutoDiff.Variable> variables = new List <AutoDiff.Variable>();
List <AutoDiff.Variable> parameters = new List <AutoDiff.Variable>();
List <string> variableNames = new List <string>();
AutoDiff.Term func;
if (!TryTransformToAutoDiff(tree.Root.GetSubtree(0), variables, parameters, variableNames, updateVariableWeights, out func))
{
throw new NotSupportedException("Could not optimize constants of symbolic expression tree due to not supported symbols used in the tree.");
}
if (variableNames.Count == 0)
{
return(0.0);
}
AutoDiff.IParametricCompiledTerm compiledFunc = func.Compile(variables.ToArray(), parameters.ToArray());
List <SymbolicExpressionTreeTerminalNode> terminalNodes = null;
if (updateVariableWeights)
{
terminalNodes = tree.Root.IterateNodesPrefix().OfType <SymbolicExpressionTreeTerminalNode>().ToList();
}
else
{
terminalNodes = new List <SymbolicExpressionTreeTerminalNode>(tree.Root.IterateNodesPrefix().OfType <ConstantTreeNode>());
}
//extract inital constants
double[] c = new double[variables.Count];
{
c[0] = 0.0;
c[1] = 1.0;
int i = 2;
foreach (var node in terminalNodes)
{
ConstantTreeNode constantTreeNode = node as ConstantTreeNode;
VariableTreeNode variableTreeNode = node as VariableTreeNode;
if (constantTreeNode != null)
{
c[i++] = constantTreeNode.Value;
}
else if (updateVariableWeights && variableTreeNode != null)
{
c[i++] = variableTreeNode.Weight;
}
}
}
double[] originalConstants = (double[])c.Clone();
double originalQuality = SymbolicRegressionSingleObjectivePearsonRSquaredEvaluator.Calculate(interpreter, tree, lowerEstimationLimit, upperEstimationLimit, problemData, rows, applyLinearScaling);
alglib.lsfitstate state;
alglib.lsfitreport rep;
int info;
IDataset ds = problemData.Dataset;
double[,] x = new double[rows.Count(), variableNames.Count];
int row = 0;
foreach (var r in rows)
{
for (int col = 0; col < variableNames.Count; col++)
{
x[row, col] = ds.GetDoubleValue(variableNames[col], r);
}
row++;
}
double[] y = ds.GetDoubleValues(problemData.TargetVariable, rows).ToArray();
int n = x.GetLength(0);
int m = x.GetLength(1);
int k = c.Length;
alglib.ndimensional_pfunc function_cx_1_func = CreatePFunc(compiledFunc);
alglib.ndimensional_pgrad function_cx_1_grad = CreatePGrad(compiledFunc);
try {
alglib.lsfitcreatefg(x, y, c, n, m, k, false, out state);
alglib.lsfitsetcond(state, 0.0, 0.0, maxIterations);
//alglib.lsfitsetgradientcheck(state, 0.001);
alglib.lsfitfit(state, function_cx_1_func, function_cx_1_grad, null, null);
alglib.lsfitresults(state, out info, out c, out rep);
}
catch (ArithmeticException) {
return(originalQuality);
}
catch (alglib.alglibexception) {
return(originalQuality);
}
//info == -7 => constant optimization failed due to wrong gradient
if (info != -7)
{
UpdateConstants(tree, c.Skip(2).ToArray(), updateVariableWeights);
}
var quality = SymbolicRegressionSingleObjectivePearsonRSquaredEvaluator.Calculate(interpreter, tree, lowerEstimationLimit, upperEstimationLimit, problemData, rows, applyLinearScaling);
if (!updateConstantsInTree)
{
UpdateConstants(tree, originalConstants.Skip(2).ToArray(), updateVariableWeights);
}
if (originalQuality - quality > 0.001 || double.IsNaN(quality))
{
UpdateConstants(tree, originalConstants.Skip(2).ToArray(), updateVariableWeights);
return(originalQuality);
}
return(quality);
}
public bool Covers(IDataset dataset, int row)
{
return(!SplitAttributes.Where((t, i) => !Comparisons[i].Compare(dataset.GetDoubleValue(t, row), SplitValues[i])).Any());
}
private static double[,] PCAReduce(IDataset dataset, IEnumerable<int> rows, IEnumerable<string> variables) {
var instances = rows.ToArray();
var attributes = variables.ToArray();
var data = new double[instances.Length, attributes.Length + 1];
for (int j = 0; j < attributes.Length; j++) {
int i = 0;
var values = dataset.GetDoubleValues(attributes[j], instances);
foreach (var v in values) {
data[i++, j] = v;
}
}
int info;
double[] variances;
var matrix = new double[0, 0];
alglib.pcabuildbasis(data, instances.Length, attributes.Length, out info, out variances, out matrix);
var result = new double[instances.Length, matrix.GetLength(1)];
int r = 0;
foreach (var inst in instances) {
int i = 0;
foreach (var attrib in attributes) {
double val = dataset.GetDoubleValue(attrib, inst);
for (int j = 0; j < result.GetLength(1); j++)
result[r, j] += val * matrix[i, j];
i++;
}
r++;
}
return result;
}
