R: Extract a rectangular perimeter

rectPERIM {GEOmap} | R Documentation

## Extract a rectangular perimeter

### Description

Extract a rectangular perimeter

### Usage

    rectPERIM(x, y = 1, pct = 0)

### Arguments

`x` | x values or a list include x, y members
`y` | y values, if missing, x must be a list
`pct` | Percent expansion, based on range of x and y values. If pct>1 it is divided by 100 to get a fractional percent expansion.

### Details

The rectangular box will be expanded based on the percent pct.

### Value

list of x, y values from lower left corner counter clockwise around perimeter

### Author(s)

Jonathan M. Lees<jonathan.lees@unc.edu>

### See Also

getGEOperim

### Examples

    fx  =rnorm(20)
    fy = rnorm(20)

    plot(fx, fy, xlim=c(-4, 4), ylim=c(-4,4))
    rp = rectPERIM(fx, fy)

    polygon(rp)
    text(rp, labels=1:4, pos=c(1,1,3,3), font=2, cex=2)

    fx2  =rnorm(20, m=-1)
    fy2 = rnorm(20, m=-1)

    Fx = list(x=fx2, y=fy2)

    points(Fx$x, Fx$y, col='red')

    rp = rectPERIM(Fx)

    polygon(rp, border='red')

    ########   try expanding the perim:

    plot(fx, fy, xlim=c(-4, 4), ylim=c(-4,4), asp=1)
    rp = rectPERIM(fx, fy, pct=0.1)

    polygon(rp)

    rp = rectPERIM(fx, fy, pct=0.2)

    polygon(rp)

[Package GEOmap version 2.4-0 Index]