Panel Function for Display Marked by groups

These are panel functions for Trellis displays useful when a grouping variable is specified for use within panels. The x (and y where appropriate) variables are plotted with different graphical parameters for each distinct value of the grouping variable.

Usage

panel.superpose(x, y = NULL, subscripts, groups,
                panel.groups = "panel.xyplot",
                ...,
                col, col.line, col.symbol,
                pch, cex, fill, font,
                fontface, fontfamily,
                lty, lwd, alpha,
                type = "p",
                grid = lattice.getOption("default.args")$grid,
                distribute.type = FALSE)
panel.superpose.2(..., distribute.type = TRUE)

panel.superpose.plain(...,
                      col, col.line, col.symbol,
                      pch, cex, fill, font,
                      fontface, fontfamily,
                      lty, lwd, alpha)

Arguments

x,y

Coordinates of the points to be displayed. Usually numeric.

panel.groups

The panel function to be used for each subgroup of points. Defaults to panel.xyplot.

To be able to distinguish between different levels of the originating group inside panel.groups, it will be supplied two special arguments called group.number and group.value which will hold the numeric code and factor level corresponding to the current level of groups. No special care needs to be taken when writing a panel.groups function if this feature is not used.

subscripts

An integer vector of subscripts giving indices of the x and y values in the original data source. See the corresponding entry in xyplot for details.

groups

A grouping variable. Different graphical parameters will be used to plot the subsets of observations given by each distinct value of groups. The default graphical parameters are obtained from the "superpose.symbol" and "superpose.line" settings using trellis.par.get wherever appropriate.

type

Usually a character vector specifying how each group should be drawn. Formally, it is passed on to the panel.groups function, which must know what to do with it. By default, panel.groups is panel.xyplot, whose help page describes the admissible values.

The functions panel.superpose and panel.superpose.2 differ only in the default value of distribute.type, which controls the way the type argument is interpreted. If distribute.type = FALSE, then the interpretation is the same as for panel.xyplot for each of the unique groups. In other words, if type is a vector, all the individual components are honoured concurrently. If distribute.type = TRUE, type is replicated to be as long as the number of unique values in groups, and one component used for the points corresponding to the each different group. Even in this case, it is possible to request multiple types per group, specifying type as a list, each component being the desired type vector for the corresponding group.

If distribute.type = FALSE, any occurrence of "g" in type causes a grid to be drawn, and all such occurrences are removed before type is passed on to panel.groups.

grid

Logical flag specifying whether a background reference grid should be drawn. See panel.xyplot for details.

col

A vector color specification. See Details.

col.line

A vector color specification. See Details.

col.symbol

A vector color specification. See Details.

pch

A vector plotting character specification. See Details.

cex

A vector size factor specification. See Details.

fill

A vector fill color specification. See Details.

font, fontface, fontfamily

A vector color specification. See Details.

lty

A vector color specification. See Details.

lwd

A vector color specification. See Details.

alpha

A vector alpha-transparency specification. See Details.

...

Extra arguments. Passed down to panel.superpose from panel.superpose.2, and to panel.groups from panel.superpose.

distribute.type

logical controlling interpretation of the type argument.

Details

panel.superpose divides up the x (and optionally y) variable(s) by the unique values of groups[subscripts], and plots each subset with different graphical parameters. The graphical parameters (col.symbol, pch, etc.) are usually supplied as suitable atomic vectors, but can also be lists. When panel.groups is called for the i-th level of groups, the corresponding element of each graphical parameter is passed to it. In the list form, the individual components can themselves be vectors.

The actual plot for each subgroup is created by the panel.groups function. With the default panel.groups, the col argument is overridden by col.line and col.symbol for lines and points respectively, which default to the "superpose.line" and "superpose.symbol" settings. However, col will still be supplied as an argument to panel.groups functions that make use of it, with a default of "black". The defaults of other graphical parameters are also taken from the "superpose.line" and "superpose.symbol" settings as appropriate. The alpha parameter takes it default from the "superpose.line" setting.

panel.superpose and panel.superpose.2 differ essentially in how type is interpreted by default. The default behaviour in panel.superpose is the opposite of that in S, which is the same as that of panel.superpose.2.

panel.superpose.plain is the same as panel.superpose, except that the default settings for the style arguments are the same for all groups and are taken from the default plot style. It is used in xyplot.ts.

See also

Different functions when used as panel.groups gives different types of plots, for example panel.xyplot, panel.dotplot and panel.average (This can be used to produce interaction plots).

See Lattice for an overview of the package, and xyplot for common arguments (in particular, the discussion of the extended formula interface and the groups argument).

Author

Deepayan Sarkar Deepayan.Sarkar@R-project.org (panel.superpose.2 originally contributed by Neil Klepeis)