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Interacting with Individual Plots

Rotating plots and scatterplot matrices are interactive plots. Simple scatter plots also allow some interaction: If you select the Show Labels option in the plot menu a label will appear next to a highlighted point. You can use either the selecting or the brushing mode to highlight points. The default labels are of the form ``0'', ``1'', ... . (In Lisp it is conventional to start numbering indices with 0, rather than 1.) Most plotting functions allow you to supply a list of case labels using the :point-labels keyword.

Another option, useful in viewing large data sets, is to remove a subset of the points from your plot. This can be done by selecting the points you want to remove and then choosing Remove Selection from the plot menu. The plot can then be rescaled using the Rescale Plot option. Alternatively, the Focus on Selection menu item removes all unselected points from the plot.

When a set of points is selected in a plot you can change the symbol used to display the points using the Selection Symbol item. On systems with color monitors you can set the color of selected points with the Selection Color item.

You can save the indices of the selected points in a variable by choosing the Selection... item in the plot menu. A dialog will ask you for a name for the selection. When no points are selected you can use the Selection... menu item to specify the indices of the points to select. A dialog will ask you for an expression for determining the selection to use. The expression can be any Lisp expression that evaluates to a list of indices.

Luke Tierney
Tue Jan 21 15:04:48 CST 1997