cnvrt.coords {Hmisc} | R Documentation

## Convert between the 5 different coordinate sytems on a graphical device

### Description

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:

`usr` | The coordinates of the input points in usr (User) coordinates.
`plt` | The coordinates of the input points in plt (Plot) coordinates.
`fig` | The coordinates of the input points in fig (Figure) coordinates.
`dev` | The coordinates of the input points in dev (Device) coordinates.
`tdev` | The coordinates of the input points in tdev (Total Device) coordinates.

### 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.

### Author(s)

Greg Snow greg.snow@imail.org

### 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)

[Package Hmisc version 3.17-3 Index]