TAtlasPlotAnalysis

AddHistogram method

class function AddHistogram(Plot: TAtlasPlot; const Values: TArray<Double>; Bins: Integer = 0; const Title: string = 'Frequency'): TAtlasPlotSeries; static;

Adds a bar series (pkBar) with one bar per bin of TAtlasStats.Histogram(Values, Bins): X is the bin centre, Y the count. Bins 0 uses Sturges' rule. Raises when Plot is nil or the histogram is rejected.

Added := TAtlasPlotAnalysis.AddHistogram(Plot, [1, 2, 2, 3, 3, 3, 4, 4, 5], 4, 'Counts');

AddPolynomialFit method

class function AddPolynomialFit(Plot: TAtlasPlot; Source: TAtlasPlotSeries; Degree: Integer; out RSquared: Double; Samples: Integer = 64): TAtlasPlotSeries; static;

Fits a least-squares polynomial of Degree (1 to 6) through the non-null points of Source and adds it as a line series titled <Source title> fit(<Degree>), with Samples (2 to 10000) evenly spaced points from the smallest to the largest X. RSquared receives the fit's R squared (0 when the call fails). Raises when Source is nil or belongs to another chart, when Samples is out of range, or when the fit is rejected.

Added := TAtlasPlotAnalysis.AddPolynomialFit(Plot, Measured, 2, RSquared);
Added.LineWidth := 3;

AddExponentialSmoothing method

class function AddExponentialSmoothing(Plot: TAtlasPlot; Source: TAtlasPlotSeries; const Alpha: Double): TAtlasPlotSeries; static;

Adds a line series titled <Source title> smooth(<Alpha>) with the exponentially smoothed Y values of the non-null points of Source, in point order, at their original X. Alpha must be above 0 and at most 1.

Added := TAtlasPlotAnalysis.AddExponentialSmoothing(Plot, Measured, 0.3);

Add a fit and a smoothed line to measured points

The R squared of the fit goes into the chart title.

uses
  System.SysUtils, System.Math, Vcl.Controls, Vcl.Forms, Atlas.PlotSeries, Atlas.Plot,
  Atlas.PlotAnalysis;

function AddAnalysedPlot(Form: TForm): TAtlasPlot;
var Measured: TAtlasPlotSeries; I: Integer; RSquared: Double;
begin
  Result := TAtlasPlot.Create(Form);
  Result.Parent := Form;
  Result.Align := alClient;
  Measured := Result.AddSeries('Measured', pkPoint);
  for I := 0 to 40 do
    Measured.Add(I / 4, 3 + 0.9 * (I / 4) - 0.35 * Sqr(I / 4 - 5) + 1.5 * Sin(I * 2.3));
  TAtlasPlotAnalysis.AddPolynomialFit(Result, Measured, 2, RSquared).LineWidth := 3;
  TAtlasPlotAnalysis.AddExponentialSmoothing(Result, Measured, 0.3);
  Result.Title := Format('Quadratic fit, R squared %.3f', [RSquared]);
end;

Show the distribution of a sample

Replaces whatever the chart showed with a histogram.

uses
  System.SysUtils, Atlas.Plot, Atlas.PlotAnalysis;

procedure ShowDistribution(Plot: TAtlasPlot; const Values: TArray<Double>);
begin
  Plot.BeginUpdate;
  try
    Plot.Clear;
    TAtlasPlotAnalysis.AddHistogram(Plot, Values, 0, 'Requests');   // Sturges' rule
    Plot.Title := Format('%d values', [Length(Values)]);
  finally
    Plot.EndUpdate;
  end;
end;