rotation: Rotate a set of point by a certain angle

In AEM: Tools to construct Asymmetric eigenvector maps (AEM) spatial variables

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.

Warning

This function was not design to handle a large number of rows in xy. To use this function for a set of coordinates with more than 1500 entries is not recommended.

Author(s)

F. Guillaume Blanchet

Examples

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

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

for(i in rad){
	coords.rot<-rotation(coords,i)
	plot(coords.rot)
}

### 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)

AEM documentation built on May 2, 2019, 5:25 p.m.