Hi:

I am a newbie using grid and lattice.
I want to update a xyplot without redrawing and I was wondering if there is
a way of adding a point to a pointsGrob ?

For example, take the example from the "R Graphics Book"  page 218-219:
grid.newpage()
angle <- seq(0, 2*pi, length=21)[-21]
x <- cos(angle)
y <- sin(angle)
xyplot( y ~ x, aspect = 1)

Lets say I take the pointsGrob below:

getNames()
  [1] "GRID.rect.748"     "plot1.xlab"        "plot1.ylab"
"GRID.segments.749"
  [5] "GRID.segments.750" "GRID.text.751"     "GRID.segments.752"
"GRID.text.753"
  [9] "GRID.segments.754" "GRID.points.755"   "GRID.rect.756"
pg = grid.get("GRID.points", grep=TRUE)
pg
   points[GRID.points.755]

Is there a way I can add a point to pg (or "GRID.points.755") to update the
xyplot without redrawing all the points ?
If redrawing is obligatory,  is there way of redrawing the least elements of
the xyplot ?

Searched for a long time but could not find anything, even if this seems
like a fairly basic operation.
I guess this may well go against the grid's package "philosophy" or
"architecture" ?

       Thanks.

               Daniel.

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