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CVATRELLIS procedure

Displays the distribution of groups over 2 dimensions from a CVA analysis using a trellis of bar or pie charts (R.W. Payne).


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


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


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.


CVATRELLIS uses the D2GROUPS procedure to calculate and plot the replications of the groups.

See also

Directive: CVA.
Commands for: Multivariate and cluster analysisGraphics.


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 [PLOT=piechart,scaledpiechart,key]
Updated on February 6, 2023

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