Displays the distribution of groups over 2 dimensions from a `CVA`

analysis using a trellis of bar or pie charts (R.W. Payne).

### Options

`PLOT` = string tokens |
What to plot (`barchart` , `piechart` , `scaledpiechart` , `key` ); default `barc` , `key` |

`NPARTITIONS` = scalar |
Number of partitions along each axis; default 8 |

`COLOURS` = variate or text |
Colours for the groups; default uses the colours defined for pens 2 upwards |

`KEYHEIGHT` = scalar |
Height of the key; default 0.1 |

`SAVE` = pointer |
Save structure from the CVA analysis to display; default displays the most recent analysis |

### Parameters

`YDIMENSION` = scalars |
Dimension for the y-axis for each graph; default 1 |

`XDIMENSION` = scalars |
Dimension for the x-axis for each graph; default 2 |

`TITLE` = texts |
Title for each graph |

### Description

`CVATRELLIS`

can be used to display scores from a `CVA`

analysis that contained a large number of units. The `SAVE`

option can supply a save structure from the `CVA`

analysis to display. The default is to display scores from the most recent `CVA`

.

The y and x dimensions to display are specified by the `YDIMENSION`

and `XDIMENSION`

parameters, respectively. The default displays dimensions 1 and 2.

`CVATRELLIS`

divides the plane into a trellis of squares, and calculates and plots the replications of the groups in each of the squares using the `D2GROUPS`

procedure. The `PLOT`

option specifies how the replications are plotted, with settings:

`barchart`

plots a trellis with a bar chart in each square,

`piechart`

plots a trellis with a pie chart in each square, with a title showing the number of points in the square,

`scaledpiechart`

plots a trellis with a pie chart in each square, each one scaled according to the number of points in the square, and

`key`

includes a key showing the colour used for each group. The default is to plot a bar chart with a key.

The `NPARTITIONS`

option specifies the number of partitions (i.e the number of trellis boxes) along each dimension; default 8. The `KEYHEIGHT`

option specifies the height of the key. This must not be less than 0.1 or greater than 0.5. The default is 0.1. The `COLOURS`

option can specify either a variate or a text to define the colours to be used for the groups. (See `PEN `

for details.) The default is to use the colours defined for pens 2 upwards. The `TITLE`

parameter can supply a title for the plots; by default the is none. Options: `PLOT`

, `NPARTITIONS`

, `COLOURS`

, `KEYHEIGHT`

, `SAVE`

. Parameters: `YDIMENSION`

, `XDIMENSION`

, `TITLE`

.

### Method

`CVATRELLIS`

uses the `D2GROUPS`

procedure to calculate and plot the replications of the groups.

### See also

Directive: `CVA`

.

Procedures: `CVAPLOT`

, `CVASCORES`

, `D2GROUPS`

.

Commands for: Multivariate and cluster analysis, Graphics.

### Example

CAPTION 'CVATRELLIS example'; STYLE=meta SPLOAD '%data%/Iris.gsh' SSPM [TERMS=Petal_Length,Petal_Width,Sepal_Length,Sepal_Width; \ GROUPS=Species] iris_ssp FSSP iris_ssp CVA [PRINT=roots,loadings,means] iris_ssp CVATRELLIS CVATRELLIS [PLOT=piechart,scaledpiechart,key]