[R] (x,y) coordinates for grid.text()

David Afshartous dafshartous at med.miami.edu
Tue Mar 4 18:12:33 CET 2008



All,

When using grid.text it seems my supplied (x,y) coordinates are being
plotted only in npc (normalized parent coordinates) where (.5,.5) is the
center of the graph.  How do I allow (x,y) to be coordinates corresponding
to the (x,y) values in the graph?   The examples in ?grid.text seem to do
this.  (I think the problem lies in how x and y are defined with respect to
unit ).   Any help much appreciated.  Sample code below.

Cheers,
David




y = c( 0.4,  0.6, -0.1,  0.3,  0.3, -0.2,  0.7,  0.7,  0.2,  0.0,  0.9,
-0.1,  0.6, -1.1,  0.8, -1.0,  0.4,  0.1,  0.7, -0.2, -0.1, -0.1,  2.2,
0.7,  1.1,  0.2, -0.2, -0.9,  0.4,  0.1, -0.3, -0.4)
x = c(4.1000,  4.9600,  1.2000,  3.9000,  3.1875,  1.9000,  1.8625,
0.7650,  1.5750,  2.4700,  1.6250,  1.5500,  2.3125,  1.3125,  1.0600,
-0.5500,  1.1000,  0.0200, -0.0375,  3.4600,  2.5250,  2.0950,  0.8000,
1.6050, -0.4150, -0.7300,  1.1550,  1.4850,  2.2000,  2.2500,  0.6000,
2.1000)
junk.frm = data.frame(ID = rep(1:16, each = 2), x, y, z = rep(c("D", "P"),
16))
xyplot(y ~ x , data = junk.frm[junk.frm$z =="D",], type = c("g", "p",
"smooth"), pch = 20)

grid.text("put text here", x = 1, y = 1.5)  # doesn't show up
grid.text("put text here", x = .4, y = .7) # shows up in the desired
location but this is for npc



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