cnvrt.coords
Convert between the 5 different coordinate sytems on a graphical device
Takes a set of coordinates in any of the 5 coordinate systems (usr, plt, fig, dev, or tdev) and returns the same points in all 5 coordinate systems.
Usage
cnvrt.coords(x, y = NULL, input = c("usr", "plt", "fig", "dev","tdev"))
Arguments
 x
 Vector, Matrix, or list of x coordinates (or x and y coordinates), NA's allowed.
 y
 y coordinates (if
x
is a vector), NA's allowed.  input
 Character scalar indicating the coordinate system of the input points.
Details
Every plot has 5 coordinate systems:
usr (User): the coordinate system of the data, this is shown by the tick marks and axis labels.
plt (Plot): Plot area, coordinates range from 0 to 1 with 0 corresponding to the x and y axes and 1 corresponding to the top and right of the plot area. Margins of the plot correspond to plot coordinates less than 0 or greater than 1.
fig (Figure): Figure area, coordinates range from 0 to 1 with 0 corresponding to the bottom and left edges of the figure (including margins, label areas) and 1 corresponds to the top and right edges. fig and dev coordinates will be identical if there is only 1 figure area on the device (layout, mfrow, or mfcol has not been used).
dev (Device): Device area, coordinates range from 0 to 1 with 0 corresponding to the bottom and left of the device region within the outer margins and 1 is the top and right of the region withing the outer margins. If the outer margins are all set to 0 then tdev and dev should be identical.
tdev (Total Device): Total Device area, coordinates range from 0 to 1 with 0 corresponding to the bottom and left edges of the device (piece of paper, window on screen) and 1 corresponds to the top and right edges.
Value

A list with 5 components, each component is a list with vectors named
x and y. The 5 sublists are:
Note
You must provide both x and y, but one of them may be NA
.
This function is becoming depricated with the new functions
grconvertX
and grconvertY
in R version 2.7.0 and beyond.
These new functions use the correct coordinate system names and have
more coordinate systems available, you should start using them instead.
See Also
par
specifically 'usr','plt', and 'fig'. Also
'xpd' for plotting outside of the plotting region and 'mfrow' and
'mfcol' for multi figure plotting. subplot
,
grconvertX
and grconvertY
in R2.7.0 and later
Examples
old.par < par(no.readonly=TRUE)
par(mfrow=c(2,2),xpd=NA)
# generate some sample data
tmp.x < rnorm(25, 10, 2)
tmp.y < rnorm(25, 50, 10)
tmp.z < rnorm(25, 0, 1)
plot( tmp.x, tmp.y)
# draw a diagonal line across the plot area
tmp1 < cnvrt.coords( c(0,1), c(0,1), input='plt' )
lines(tmp1$usr, col='blue')
# draw a diagonal line accross figure region
tmp2 < cnvrt.coords( c(0,1), c(1,0), input='fig')
lines(tmp2$usr, col='red')
# save coordinate of point 1 and y value near top of plot for future plots
tmp.point1 < cnvrt.coords(tmp.x[1], tmp.y[1])
tmp.range1 < cnvrt.coords(NA, 0.98, input='plt')
# make a second plot and draw a line linking point 1 in each plot
plot(tmp.y, tmp.z)
tmp.point2 < cnvrt.coords( tmp.point1$dev, input='dev' )
arrows( tmp.y[1], tmp.z[1], tmp.point2$usr$x, tmp.point2$usr$y,
col='green')
# draw another plot and add rectangle showing same range in 2 plots
plot(tmp.x, tmp.z)
tmp.range2 < cnvrt.coords(NA, 0.02, input='plt')
tmp.range3 < cnvrt.coords(NA, tmp.range1$dev$y, input='dev')
rect( 9, tmp.range2$usr$y, 11, tmp.range3$usr$y, border='yellow')
# put a label just to the right of the plot and
# near the top of the figure region.
text( cnvrt.coords(1.05, NA, input='plt')$usr$x,
cnvrt.coords(NA, 0.75, input='fig')$usr$y,
"Label", adj=0)
par(mfrow=c(1,1))
## create a subplot within another plot (see also subplot)
plot(1:10, 1:10)
tmp < cnvrt.coords( c( 1, 4, 6, 9), c(6, 9, 1, 4) )
par(plt = c(tmp$dev$x[1:2], tmp$dev$y[1:2]), new=TRUE)
hist(rnorm(100))
par(fig = c(tmp$dev$x[3:4], tmp$dev$y[3:4]), new=TRUE)
hist(rnorm(100))
par(old.par)