shape (version 1.1)

rotatexy: rotates 2-column matrix around a midpoint

Description

rotates xy values around a midpoint; xy is either a 2-columned matrix or a 2-valued vector if asp=TRUE, the aspect ratio is kept

Usage

rotatexy(xy, angle, mid=colMeans(xy), asp=FALSE)

Arguments

xy

matrix with 2 columns, to be rotated

angle

angle of rotation, in degrees

mid

rotation point, default=centroid

asp

if true: aspect ratio is kept

Value

• a 2-column matrix with rotated values

Details

rotates xy values around a midpoint; xy is either a 2-columned matrix or a 2-valued vector if asp=TRUE, the aspect ratio is kept

Examples

x <- seq(0,2*pi,pi/100)
  y <- sin(x)
  cols <- intpalette(c("blue","green","yellow","red"),n=500)
  cols <- c(cols,rev(cols))
  plot(x,y,type="l",ylim=c(-3,3),main="rotatexy",col=cols[1],
       lwd=2)
  for (i in 2:1000) lines(rotatexy(cbind(x,y),angle=0.18*i),
                          col=cols[i],lwd=2)
  
  cols <- femmecol(1000)
  plot(x,y,xlim=c(-1,1),ylim=c(-1,1),main="rotatexy",
       col=cols[1],type="n")
  for (i in 2:1000) {xy<-rotatexy(c(0,1),angle=0.36*i, mid=c(0,0));
                    points(xy[1],xy[2],col=cols[i],pch=".",cex=2)}