Transform Point Array
Flip (reflect), rotate or slide (translate) an array of points. Methods
are provided for ‘traps’ objects that ensure other attributes are
retained. The methods may be used with rbind.traps to
create complex geometries.
flip (object, lr = F, tb = F, ...) rotate (object, degrees, centrexy = NULL, ...) shift (object, shiftxy, ...) ## S3 method for class 'traps' flip(object, lr = F, tb = F, ...) ## S3 method for class 'traps' rotate(object, degrees, centrexy = NULL, ...) ## S3 method for class 'traps' shift(object, shiftxy, ...) ## S3 method for class 'popn' flip(object, lr = F, tb = F, ...) ## S3 method for class 'popn' rotate(object, degrees, centrexy = NULL, ...) ## S3 method for class 'popn' shift(object, shiftxy, ...) ## S3 method for class 'mask' shift(object, shiftxy, ...)
object |
a 2-column matrix or object that can be coerced to a matrix |
lr |
either logical for whether array should be flipped left-right, or numeric value for x-coordinate of axis about which it should be flipped left-right |
tb |
either logical for whether array should be flipped top-bottom, or numeric value for y-coordinate of axis about which it should be flipped top-bottom |
degrees |
clockwise angle of rotation in degrees |
centrexy |
vector with xy coordinates of rotation centre |
shiftxy |
vector of x and y displacements |
... |
other arguments (not used) |
flip reflects points about a vertical or horizontal axis. Logical
values for lr or tb indicate that points should be flipped
about the mean on the relevant axis. Numeric values indicate the
particular axis value(s) about which points should be flipped. The
default arguments result in no change.
shift shifts the location of each point by the desired amount
on each axis.
rotate rotates the array about a designated point. If
centrexy is NULL then rotation is about (0,0)
(rotate.default), the array centre (rotate.traps), or the
centre of the bounding box (rotate.popn).
A matrix or object of class ‘traps’ or ‘popn’ with the coordinates of each point transformed as requested.
temp <- matrix(runif (20) * 2 - 1, nc = 2) ## flip temp2 <- flip(temp, lr = 1) plot(temp, xlim=c(-1.5,4), ylim = c(-1.5,1.5), pch = 16) points (temp2, pch = 1) arrows (temp[,1], temp[,2], temp2[,1], temp2[,2], length = 0.1) abline(v = 1, lty = 2) ## rotate temp2 <- rotate(temp, 25) plot(temp, xlim=c(-1.5,1.5), ylim = c(-1.5,1.5), pch = 16) points (0,0, pch=2) points (temp2, pch = 1) arrows (temp[,1], temp[,2], temp2[,1], temp2[,2], length = 0.1) ## shiftxy temp2 <- shift(temp, c(0.1, 0.1)) plot(temp, xlim=c(-1.5,1.5), ylim = c(-1.5,1.5), pch = 16) points (0,0, pch=2) points (temp2, pch = 1) arrows (temp[,1], temp[,2], temp2[,1], temp2[,2], length = 0.1) ## flip.traps par(mfrow = c(1,2), xpd = TRUE) traps1 <- make.grid(nx = 8, ny = 6, ID = "numxb") traps2 <- flip (traps1, lr = TRUE) plot(traps1, border = 5, label = TRUE, offset = 7, gridl = FALSE) plot(traps2, border = 5, label = TRUE, offset = 7, gridl = FALSE) par(mfrow = c(1,1), xpd = FALSE) ## rotate.traps hollow1 <- make.grid(nx = 8, ny = 8, hollow = TRUE) nested <- rbind (hollow1, rotate(hollow1, 45, c(70, 70))) plot(nested, gridlines = FALSE) ## shift.traps hollow1 <- make.grid(nx = 8, ny = 8, hollow = TRUE) hollow2 <- shift(make.grid(nx = 6, ny = 6, hollow = TRUE), c(20, 20)) nested <- rbind (hollow1, hollow2) plot(nested, gridlines = FALSE, label = TRUE)
Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.