rotation: Rotate a set of point by a certain angle

In spdep: Spatial Dependence: Weighting Schemes, Statistics and Models

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

Example output

Loading required package: sp
Loading required package: Matrix
             [,1]       [,2]
 [1,] -0.93470523 0.26550866
 [2,] -0.21214252 0.37212390
 [3,] -0.65167377 0.57285336
 [4,] -0.12555510 0.90820779
 [5,] -0.26722067 0.20168193
 [6,] -0.38611409 0.89838968
 [7,] -0.01339033 0.94467527
 [8,] -0.38238796 0.66079779
 [9,] -0.86969085 0.62911404
[10,] -0.34034900 0.06178627
[11,] -0.48208012 0.20597457
[12,] -0.59956583 0.17655675
[13,] -0.49354131 0.68702285
[14,] -0.18621760 0.38410372
[15,] -0.82737332 0.76984142
[16,] -0.66846674 0.49769924
[17,] -0.79423986 0.71761851
[18,] -0.10794363 0.99190609
[19,] -0.72371095 0.38003518
[20,] -0.41127443 0.77744522

spdep documentation built on Aug. 19, 2017, 3:01 a.m.