R: Rotate a set of point by a certain angle

Rotation {spdep} | R Documentation

## Rotate a set of point by a certain angle

### Description

Rotate a set of XY coordinates by an angle (in radians)

### Usage

    Rotation(xy, angle)

### Arguments

`xy` | A 2-columns matrix or data frame containing a set of X and Y coordinates.
`angle` | Numeric. A scalar giving the angle at which the points should be rotated. The angle is in radians.

### Value

A 2-columns matrix of the same size as `xy` giving the rotated coordinates.

### Author(s)

F. Guillaume Blanchet

### Examples

    set.seed(1)
    ### Create a set of coordinates
    coords <- cbind(runif(20), runif(20))

    ### Create a series of angles
    rad <- seq(0, pi, l=20)

    opar <- par(mfrow=c(5,4), mar=c(3,3,1,1))
    for(i in rad){
    	coords.rot <- Rotation(coords, i)
    	plot(coords.rot, xlab="", ylab="")
    }
    par(opar)

    ### Rotate the coordinates by an angle of 90 degrees
    coords.90 <- Rotation(coords, 90*pi/180)
    coords.90

    plot(coords, xlim=range(rbind(coords.90,coords)[,1]),
     ylim=range(rbind(coords.90,coords)[,2]), asp=1)
    points(coords.90, pch=19)

[Package spdep version 1.2-2 Index]