# How to do Scatter Plot Matrices in XGobi

## General Description

Scatter plot matrices can be drawn and brushed in XGobi after
re-structuring the data, and constructing a row groups file. It can be
achieved either with a command line argument:

` xgobi -scatmat datafilename `
or on-the-fly by selecting "Scatterplot Matrices" in the "Tools"
menu. In this latter case, it uses the active tour variables as the
subset of variables in the scatterplot matrix.

If you start up one xgobi with the data in regular format and one
xgobi with scatterplot matrix format linked brushing can be done
between the two xgobi's in the usual way.

An example using the flea beetle data.

* Layout * The layout is displayed in the figure above:
essentially variables 1:(p-1) are along the horizontal axis, and
variables 2:p stretch from top to bottom of the vertical axis. If you
use the "-scatmat" option the diagonal elements of the array will have
the variable labels associated with dummy points, so that the rows and
columns of the matrix can be labelled using the indentification mode.

To brush, go into "Brush" mode and select color/glyph and start
painting in one of the cells.

More information on
XGobi, and the
manipulation controls paper.

Dianne Cook, Dept of Statistics, ISU, 325 Snedecor Hall, Ames, IA 50011-1210

Tel: (515) 294 8865, Fax: (515) 294 4040

email: dicook@iastate.edu

http://www.public.iastate.edu/~dicook/

Last revision: Mon Sep 27 15:02:38 CDT 1999