[R] coloring individual points in lattice xyplot

[Deepayan Sarkar]

On 7/4/06, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> OK.  It looks like I need to go to the lower level llines and lpoints to
> do this.  I wrote a panel routine, mypanel, and it seems to work (see
> below); however, currently it assumes types and cols are in the global
> environment or at least somewhere where they will be found.
>
> 1. Is it somehow possible to stick these into some structures set up by
> lattice already and then retrieve them from lattice from within mypanel?

Not sure what you mean by that, but I would do something like the
following (this allows 'col' to be a list as in your original post).
Note that arguments to the panel function can be supplied directly to
the high level function (that's why graphical parameters can be
supplied to xyplot in the first place).

mypanel <-
    function(x, y, subscripts, groups,
             col = 1,
             type = "p",
             ...)
{
    col <- rep(as.list(col), length = nlevels(groups))
    type <- rep(as.list(type), length = nlevels(groups))
    for(g in 1:nlevels(groups)) {
         idx <- g == groups[subscripts]
         xx <- x[idx]; yy <- y[idx];
         panel.xyplot(x[idx], y[idx],
                      col = col[[g]],
                      type = type[[g]],
                      ...)
    }
}

xyplot(y ~ c(x,x), groups = factor(col(y)),
       panel = mypanel,
       type = c("o", "p"),
       col = list("black", 1:10))


> 2. Any other improvements to the example below?
>
> mypanel <- function(x, y, subscripts, groups, ...) {
>       for(g in 1:nlevels(groups)) {
>          idx <- g == groups

This won't work for more than one panel.

>          xx <- x[idx]; yy <- y[idx]; ccols <- cols[subscripts][idx]
>          if (any(idx)) {
>             switch(types[g],
>                p = lpoints(xx, yy, col = ccols),
>                l = llines(xx, yy, col = ccols),
>                o = { lpoints(xx, yy, col = ccols)
>                         llines(xx, yy, col = ccols) })
>          }
>        }
>     }
>
> x <- 1:10
> y <- cbind(y1 = x, y2 = x+1)
> cols <- c(rep(1,10), 1:10)
> types <- c("o", "p")
> xyplot(y ~ c(x,x), groups = factor(col(y)), type = types, panel = mypanel)
>
>
>
> On 7/4/06, Deepayan Sarkar <deepayan.sarkar at gmail.com> wrote:
> > On 7/4/06, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> > > I can get the types to work or the colors but not both:
> >
> > Sorry if I wasn't clear, but I didn't mean that you could use
> > panel.superpose[.2] to do what you wanted. I only meant that you could
> > use it as a template that may help you to write your own panel
> > function. What you want is not possible with tools available in
> > lattice.
> >
> > Deepayan
> >
> > > # this gets the types right but not the colors
> > > library(lattice)
> > > x <- 1:10
> > > y <- cbind(y1 = x, y2 = x+1)
> > > cols <- c(rep(1,10), 1:10)
> > > xyplot(y ~ c(x,x), groups = col(y), type = c("o", "p"),
> > >    panel = function(x, y, subscripts, groups, ...)
> > >       panel.superpose.2(x, y, subscripts, groups, col = cols[subscripts], ...)
> > > )
> > >
> > >
> > > # this gets the colors right but not the types
> > > library(lattice)
> > > x <- 1:10
> > > y <- cbind(y1 = x, y2 = x+1)
> > > cols <- c(rep(1,10), 1:10)
> > > xyplot(y ~ c(x,x), groups = col(y), type = c("o", "p"),
> > >    panel = function(x, y, subscripts, groups, ...)
> > >       panel.xyplot(x, y, col = cols[subscripts], ...)
> > > )
> > >
> > >
> > > On 7/4/06, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> > > > On 7/4/06, Deepayan Sarkar <deepayan.sarkar at gmail.com> wrote:
> > > > > On 7/4/06, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> > > > > > If I wish to color groups in xyplot I can do this:
> > > > > >
> > > > > >    library(lattice)
> > > > > >    x <- 1:10
> > > > > >    y <- cbind(x, x+1)
> > > > > >    xyplot(y ~ rep(x,2), group = col(y), col = 1:2)
> > > > > >
> > > > > > How do I color different points differently within a group.
> > > > > >
> > > > > > For example, I want to produce this plot (except that I only
> > > > > > want to have two groups, not 11):
> > > > > >
> > > > > >    xyplot(y ~ rep(x,2), group = c(rep(1, 10), 2:11), col = 1:11)
> > > > > >
> > > > > > I am thinking of something like this (although
> > > > > > this does not work, its just to get the idea across):
> > > > > >
> > > > > >    xyplot(y ~ rep(x,2), group = col(y), col = list(1, 2:11))
> > > > > >
> > > > > > where, in general, I have a list with one component per group
> > > > > > whose elements are scalars to color the whole group or
> > > > > > vectors one color per point in the group.  I don't know
> > > > > > ahead of time what the list is.
> > > > > >
> > > > > > I am looking for a general approach to this within the lattice
> > > > > > xyplot plot framework; the above is just an example.
> > > > >
> > > > > The general approach is to write your own panel function. For a
> > > > > possible template, look at the functions panel.superpose and
> > > > > panel.superpose.2 and how they handle the 'type' argument.
> > > > >
> > > > > Deepayan
> > > > >
> > > >
> > > > There is no example in ?panel.superpose.  Do you think you
> > > > could provide an example for the situation in my post?
> > > >
> > > > I have done quite a bit of RSiteSearch'ing and googling prior to
> > > > posting and all the examples I found had colors that depended
> > > > on the group, none addressed the situation in my post -- i.e.
> > > > coloring individual points within groups.
> > > >
> > >
> >
> >
> > --
> > http://www.stat.wisc.edu/~deepayan/
> >
>


-- 
http://www.stat.wisc.edu/~deepayan/