# rotatexy: rotates 2-column matrix around a midpoint In shape: Functions for Plotting Graphical Shapes, Colors

## Description

rotates xy values around a midpoint; xy is either a 2-columned matrix or a 2-valued vector

## Usage

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

## Arguments

 `xy ` matrix with 2 columns, or a 2-valued vector 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

## Author(s)

Karline Soetaert <[email protected]>

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17``` ```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) } ```

shape documentation built on Feb. 9, 2018, 6:08 a.m.