Paul Johnson <pauljohn at ku.edu> wrote:
I have had trouble positioning text in figures. Because I don't know what the plotted values will be until the model is run, it is hard to write coordinates for text(x,y,""). I frequently wish there were a way to say "top left part of graph"...
As several people have replied, you need par("usr"). Here's a simple function
that does it for you. You pass "absolute" coordinates xa and ya in the range
[0,1], and it returns the user coordinates you need for "text", "legend", etc.:
-------------------------------------------------------------------------------
g.coord <- function(xa, ya, u=par("usr")) {
z <- list(x=u[1]+xa*(u[2]-u[1]), y=u[3]+ya*(u[4]-u[3]))
if (par("xlog")) z$x <- 10^z$x; if (par("ylog")) z$y <- 10^z$y
z
}
-------------------------------------------------------------------------------
To put text near the top left (but 2% in from the edges), type:
R> text(g.coord(.02,.98), "Hello", adj=c(0,1))
One subtlety: text() somehow recognizes that its first argument is a list(x,y),
and its second argument is therefore the "labels" to print. However, this
recognition fails if you use plotmath. So this doesn't work:
R> text(g.coord(.02, .98), quote(x==5), adj=c(0,1)) # Fails
but the solution is simple: you just need to name the "labels" argument:
R> text(g.coord(.02, .98), l=quote(x==5), adj=c(0,1)) # OK
(Note that's the letter "l", short for "labels".)
-- David Brahm (brahm at alum.mit.edu) -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._