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Using TDendrogram

The usage of TDendrogram is straightforward: pick the dendrogram component from the VCL palette and put it on your form. Configure the parameters as required by your application and fill the array property Data with your data.

The dendrogram is calculated and displayed automatically whenever either an element of the data matrix (property Data) or one of the clustering parameters (ClusterMethod, DistMeasure, FlexAlpha) is changed. While this behavior is quite convenient for small data sets it can become counter-productive for large data sets, since the (re)calculation of a dendrogram will require considerable time. In this case you should set the property SuppressClustAnal to TRUE before making any changes of the data and/or clustering parameters. Setting SuppressClustAnal to FALSE again will automatically update the dendrogram. The read-only property IsProcessing is set to TRUE during the recalculation of a dendrogram.

The visual appearance of the dendrogram can be controlled by various colors properties (i.e. ColorDendrogram, ColorDendrogramBackGnd, ColorScale, ColorScaleBackGnd, ColorLabelsBG, ColorEmptyArea, ColorScheme), by scale properties (i.e. DistLow, DistHigh, ObjLow, ObjHigh, DecPlaces, ScaleHeight, ScaleWidth) and by various style parameters such as the Orientation, the Margin, or the FrameStyle property.

In addition a crosshair may be displayed which can be used to measure the distance within the dendrogram (set MouseAction to maDragCrossH and use the CrossHair.OnChange event to get the coordinates of the crosshair).

Besides setting the properties DistLow, DistHigh, ObjLow, and ObjHigh for adjusting the viewport of the dendrogram, you may use either the method AutoRange to adjust the visible range in a way that the entire dendrogram is displayed, or the method SetRange to set all of these four properties at once. The viewport can be moved interactively by setting the property MouseAction accordingly (i.e. maPan, or maZoomWind).

The event OnBeforeShowObjLabel can be used to provide custom object labels for the dendrogram plot. The OnCalcDistance event is triggered when a user-defined distance measure has to be calculated.


Last Update: 2013-May-14