Hi
Deepayan Sarkar wrote:
On Wednesday 01 June 2005 05:43, Pikounis, Bill [CNTUS] wrote:
Hello,
I wish to customize the tick marks and labels of axes in panels produced by
high-level lattice functions, namely xyplot. I know I can use the scales
argument to specify values for rot, cex, etc. in the top-level call.
However, I am interested in determining values for cex and rot based on the
current panel / viewport and device. More specifically, I would like to
make adjustments when tick labels overlap on the x-axis, such as labels of
a factor. If I use base graphics, par("cin") or par("cxy") or strwidth(),
etc. can be used to develop an algorithm to adjust cex or/and rot if
needed.
I am trying to determine the parameters/settings in grid analogous to
par("cin"), etc. mentioned above, knowing that par() has no effect in
lattice / grid. I have dug around the sources for grid and lattice but
cannot seem to come up with such parameters -- most notably something like
strwidth(). I see that panel.axis() has a check.overlap argument for
labels, but I could not trace down the actual code to see how that works.
What have I overlooked, or where should I be looking?
Paul may be able to give a more insightful answer, but grid allows a string to
determine it's width in terms of itself, e.g.:
unit(1, "strwidth", data = "foo")
Or just stringWidth("foo") (and of course stringHeight("foo")).
If you want to convert that into, say, inches, you could use
convertX(unit(1, "strwidth", data = "foo"), "inches", TRUE)
[1] 0.2344092
I think this would depend on the gpars() in effect, in particular fontsize.
Yep. There's also grobWidth(textGrob("foo")), which gives you not just
the size of a string, but the size of a text graphical object. The
difference is that a text graphical object can include information about
where it will be drawn, in what font, and so on. For example,
grobWidth(textGrob("foo", gp=gpar(fontfamily="mono", cex=2))) is very
different from stringWidth("foo"). If you want to determine the size
of some text that you want to draw as part of the panel axis AND you
want it to look like the text that lattice would have drawn, then
something like this might give you what you want:
grobWidth(textGrob("your label",
gp=do.call("gpar", trellis.par.get("axis.text"))))
It is also important that you do these calculations within a panel
function so that they get evaluated within the appropriate context
(i.e., higher-level lattice graphical parameter settings have been
enforced). The result of the above call to grobWidth() could be very
different if evaluated in some other context.
Finally, if you use convertX() (or any of its ilk), be aware that
changes in the device size (e.g., resize a window) could make the
calculations invalid. Maybe we could follow this up on the r-devel
mailing list if you think this will be an issue.
Paul
Indirectly related, setting outside=TRUE in a panel.axis() call does not
produce visible labels, perhaps due to "issues of clipping" as mentioned in
its help page. How might one disable clipping for the current panel /
viewport?
At the grid level, there's a 'clip' argument to 'viewport()'. In lattice,
these are chosen from
str(trellis.par.get("clip"))
List of 2
$ panel: chr "on"
$ strip: chr "on"
(In case you are using 'trellis.focus', that can set clipping off.)
Deepayan
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