panel.superpose {lattice}  R Documentation 
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.
panel.superpose(x, y, panel.groups = "panel.xyplot", subscripts, groups, type="p", ...) panel.superpose.2(x, y, panel.groups = "panel.xyplot", subscripts, groups, type="p", ...)
x,y 
coordinates of the points to be displayed 
panel.groups 
the panel function to be used for each group of points. Defaults to
panel.xyplot (behaviour in S)

subscripts 
subscripts giving indices in original data frame 
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 superpose.symbol and superpose.line
using trellis.par.get wherever appropriate

type 
usually a character vector specifying what should be drawn for each
group, passed on to the panel.groups function, which must
know what to do with it. By default, this is
panel.xyplot , whose help page describes the admissible
values.
The two functions panel.superpose and
panel.superpose.2 differ only in the way the type
argument is interpreted. For the former, 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. For the latter, 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 plot.

... 
other arguments (mostly graphical parameters, replicated
to be as long as the number of groups), ultimately passed down to
panel.xyplot . In particular, colour can be specified using 3
arguments (col , col.line and col.symbol ), as
described in panel.xyplot .

Deepayan Sarkar Deepayan.Sarkar@Rproject.org
(panel.superpose.2
originally contributed by Neil Klepeis)
Different functions when used as panel.groups
gives different
types of plots, for example panel.xyplot
,
panel.dotplot
and panel.linejoin
(This can
be used to produce interaction plots).