contour {base} | R Documentation |
Draws contour lines for the desired levels. There is currently no documentation about the algorithm. The source code is in `$R_HOME/src/main/plot.c'.
contour(x = seq(0, 1, len = nrow(z)), y = seq(0, 1, len = ncol(z)), z, nlevels = 10, levels = pretty(zlim, nlevels), xlim = range(x, finite = TRUE), ylim = range(y, finite = TRUE), zlim = range(z, finite = TRUE), labcex = 0, col = par("fg"), lty = par("lty"), add = FALSE, ...)
x,y |
locations of grid lines at which the values in z are
measured. These must be in ascending order. By default, equally
spaced values from 0 to 1 are used. If x is a list ,
its components x$x and x$y are used for x
and y , respectively. If the list has component z this
is used for z . |
z |
a matrix containing the values to be plotted (NA s are
allowed). Note that x can be used instead of z for
convenience. |
nlevels |
number of contour levels desired iff
levels is not supplied. |
levels |
numeric vector of levels at which to draw contour lines. |
labcex |
cex for contour labelling. (not yet used) |
xlim, ylim, zlim |
x-, y- and z-limits for the plot |
col |
color for the lines drawn |
lty |
line type for the lines drawn |
add |
logical. If TRUE , add to a current plot. |
... |
additional graphical parameters (see par )
and the arguments to title may also be supplied. |
filled.contour
for ``color-filled'' contours,
image
and the graphics demo which can be invoked as
demo(graphics)
.
x <- -6:16 op <- par(mfrow = c(2, 2)) contour(outer(x, x)) z <- outer(x, sqrt(abs(x)), FUN = "/") ## Should not be necessary: z[!is.finite(z)] <- NA image(x, x, z) contour(x, x, z, col = "pink", add = TRUE) contour(x, x, z, ylim = c(1, 6)) contour(x, x, z, ylim = c(-6, 6), nlev = 20, lty = 2) par(op) ## Persian Rug Art: x <- y <- seq(-4*pi, 4*pi, len = 27) r <- sqrt(outer(x^2, y^2, "+")) opar <- par(mfrow = c(2, 2), mar = rep(0, 4)) for(f in pi^(0:3)) contour(cos(r^2)*exp(-r/f)) data("volcano") rx <- range(x <- 10*1:nrow(volcano)) ry <- range(y <- 10*1:ncol(volcano)) ry <- ry + c(-1,1) * (diff(rx) - diff(ry))/2 tcol <- terrain.colors(12) par(opar); par(mfrow=c(1,1)); opar <- par(pty = "s", bg = "lightcyan") plot(x = 0, y = 0,type = "n", xlim = rx, ylim = ry, xlab = "", ylab = "") u <- par("usr") rect(u[1], u[3], u[2], u[4], col = tcol[8], border = "red") contour(x, y, volcano, col = tcol[2], lty = "solid", add = TRUE) title("A Topographic Map of Maunga Whau", font = 4) abline(h = 200*0:4, v = 200*0:4, col = "lightgray", lty = 2, lwd = 0.1) par(opar)