# [R] Grid Points

Anupam Tyagi anuptyagi at yahoo.com
Sun Aug 20 19:30:53 CEST 2006

```Thanks. How do I retain the same scale of grid.points
from one panel to next even if the scale of the data
changes? For example: c(seq(601:700),seq(6510,7000,
by=10)) ~ seq(601:700) | gl(2,50).

--- Gabor Grothendieck <ggrothendieck at gmail.com>
wrote:

> Try this.  gl(2,50) is such that the first 50 points
> are series 1
> and the second 50 points are series 2.  The scales=
> argument
> defines the positions of the tick marks and the
> xlim= argument
> defines the x axis limits.  The layout puts the
> panels on top
> of each other rather than side by side.  strip =
> FALSE eliminates
> the strip above each panel.  type= says we want
> lines.  The
> panel function puts points at the grid locations in
> each panel
> and then calls xyplot to plot the lines.
>
> library(lattice)
> library(grid)
>
> x <- 601:700
> at <- seq(500, 800, 50)
> xyplot(x ~ x | gl(2, 50), scales = list(at = at),
> xlim = c(500, 700),
>   layout = 1:2, strip = FALSE, type = "l",
>   panel = function(...) {
>     grid.points(at, unit(rep(.01, length(at)),
> "npc"),
>       pch = 20, size = unit(.2, "char"))
>     panel.xyplot(...)
> })
>
>
> On 8/20/06, Anupam Tyagi <AnupTyagi at yahoo.com>
> wrote:
> > How do I put grid points (not grid lines) as the
> base layer of an xyplot?
> >
> > Is there a way to vary the interval at which x and
> y grid points are placed?
> >
> > Is it possible to start a graph so that Y axis
> begins at 500 and ends at 800? I
> > am only interested in focusing on the relative
> distance between the points whose
> > values are between 500 and 800, but not their
> relative distance from zero.
> >
> > Is there a way in R to draw two graphs so that
> that "share" the same X axis, but
> > without the gap that mfrow() creates? The origin
> of the top graph should be
> > where the Y-axis of the bottom graph ends. It will
> be useful for what I am
> > trying to do to have the X axis of the top graph
> be invisible.
> >
> > Anupam.
> >
> > ______________________________________________
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