/// <summary>
/// Fits data provided as xcolumn and ycolumn with a polynomial base.
/// </summary>
/// <param name="order">The order of the fit (1:linear, 2:quadratic, etc.)</param>
/// <param name="xcolumn">The column of x-values.</param>
/// <param name="ycolumn">The column of y-values.</param>
/// <returns>The fit.</returns>
public static LinearFitBySvd Fit(int order, Altaxo.Data.DataColumn xcolumn, Altaxo.Data.DataColumn ycolumn)
{
if (!(xcolumn is Altaxo.Data.INumericColumn))
{
throw new ArgumentException("The x-column must be numeric", "xcolumn");
}
if (!(ycolumn is Altaxo.Data.INumericColumn))
{
throw new ArgumentException("The y-column must be numeric", "ycolumn");
}
int firstIndex = 0;
int count = Math.Min(xcolumn.Count, ycolumn.Count);
double[] xarr = new double[count];
double[] yarr = new double[count];
double[] earr = new double[count];
var xcol = (Altaxo.Data.INumericColumn)xcolumn;
var ycol = (Altaxo.Data.INumericColumn)ycolumn;
int numberOfDataPoints = 0;
int endIndex = firstIndex + count;
for (int i = firstIndex; i < endIndex; i++)
{
double x = xcol[i];
double y = ycol[i];
if (double.IsNaN(x) || double.IsNaN(y))
{
continue;
}
xarr[numberOfDataPoints] = x;
yarr[numberOfDataPoints] = y;
earr[numberOfDataPoints] = 1;
numberOfDataPoints++;
}
return(LinearFitBySvd.FitPolymomialDestructive(order, xarr, yarr, earr, numberOfDataPoints));
}
public static string Fit(Altaxo.Gui.Graph.Gdi.Viewing.IGraphController ctrl, int order, double fitCurveXmin, double fitCurveXmax, bool showFormulaOnGraph)
{
string error;
error = GetActivePlotPoints(ctrl, out var xarr, out var yarr);
int numberOfDataPoints = xarr.Length;
if (null != error)
{
return(error);
}
string[] plotNames = GetActivePlotName(ctrl);
int numberOfParameter = order + 1;
double[] parameter = new double[numberOfParameter];
var fit = LinearFitBySvd.FitPolymomialDestructive(order, xarr, yarr, null, numberOfDataPoints);
// Output of results
Current.Console.WriteLine("");
Current.Console.WriteLine("---- " + DateTime.Now.ToString() + " -----------------------");
Current.Console.WriteLine("Polynomial regression of order {0} of {1} over {2}", order, plotNames[1], plotNames[0]);
Current.Console.WriteLine(
"Name Value Error F-Value Prob>F");
for (int i = 0; i < fit.Parameter.Length; i++)
{
Current.Console.WriteLine("A{0,-3} {1,20} {2,20} {3,20} {4,20}",
i,
fit.Parameter[i],
fit.StandardErrorOfParameter(i),
fit.TofParameter(i),
1 - FDistribution.CDF(fit.TofParameter(i), numberOfParameter, numberOfDataPoints - 1)
);
}
Current.Console.WriteLine("R²: {0}, Adjusted R²: {1}",
fit.RSquared,
fit.AdjustedRSquared);
Current.Console.WriteLine("Condition number: {0}, Loss of precision (digits): {1}", fit.ConditionNumber, Math.Log10(fit.ConditionNumber));
Current.Console.WriteLine("------------------------------------------------------------");
Current.Console.WriteLine("Source of Degrees of");
Current.Console.WriteLine("variation freedom Sum of Squares Mean Square F0 P value");
double regressionmeansquare = fit.RegressionCorrectedSumOfSquares / numberOfParameter;
double residualmeansquare = fit.ResidualSumOfSquares / (numberOfDataPoints - numberOfParameter - 1);
Current.Console.WriteLine("Regression {0,10} {1,20} {2,20} {3,20} {4,20}",
numberOfParameter,
fit.RegressionCorrectedSumOfSquares,
fit.RegressionCorrectedSumOfSquares / numberOfParameter,
regressionmeansquare / residualmeansquare,
1 - FDistribution.CDF(regressionmeansquare / residualmeansquare, numberOfParameter, numberOfDataPoints - 1)
);
Current.Console.WriteLine("Residual {0,10} {1,20} {2,20}",
numberOfDataPoints - 1 - numberOfParameter,
fit.ResidualSumOfSquares,
residualmeansquare
);
Current.Console.WriteLine("Total {0,10} {1,20}",
numberOfDataPoints - 1,
fit.TotalCorrectedSumOfSquares
);
Current.Console.WriteLine("------------------------------------------------------------");
// add the fit curve to the graph
IScalarFunctionDD plotfunction = new PolynomialFunction(fit.Parameter);
var fittedCurve = new XYFunctionPlotItem(new XYFunctionPlotData(plotfunction), new G2DPlotStyleCollection(LineScatterPlotStyleKind.Line, ctrl.Doc.GetPropertyContext()));
var xylayer = ctrl.ActiveLayer as XYPlotLayer;
if (null != xylayer)
{
xylayer.PlotItems.Add(fittedCurve);
}
return(null);
}
