contour package:graphics R Documentation _D_i_s_p_l_a_y _C_o_n_t_o_u_r_s _D_e_s_c_r_i_p_t_i_o_n: Create a contour plot, or add contour lines to an existing plot. _U_s_a_g_e: contour(x, ...) ## Default S3 method: contour(x = seq(0, 1, length.out = nrow(z)), y = seq(0, 1, length.out = ncol(z)), z, nlevels = 10, levels = pretty(zlim, nlevels), labels = NULL, xlim = range(x, finite = TRUE), ylim = range(y, finite = TRUE), zlim = range(z, finite = TRUE), labcex = 0.6, drawlabels = TRUE, method = "flattest", vfont, axes = TRUE, frame.plot = axes, col = par("fg"), lty = par("lty"), lwd = par("lwd"), add = FALSE, ...) _A_r_g_u_m_e_n_t_s: 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. labels: a vector giving the labels for the contour lines. If 'NULL' then the levels are used as labels, otherwise this is coerced by 'as.character'. labcex: 'cex' for contour labelling. This is an absolute size, not a multiple of 'par("cex")'. drawlabels: logical. Contours are labelled if 'TRUE'. method: character string specifying where the labels will be located. Possible values are '"simple"', '"edge"' and '"flattest"' (the default). See the 'Details' section. vfont: if 'NULL', the current font family and face are used for the contour labels. If a character vector of length 2 then Hershey vector fonts are used for the contour labels. The first element of the vector selects a typeface and the second element selects a fontindex (see 'text' for more information). The default is 'NULL' on graphics devices with high-quality rotation of text and 'c("sans serif", "plain")' otherwise. xlim, ylim, zlim: x-, y- and z-limits for the plot. axes, frame.plot: logical indicating whether axes or a box should be drawn, see 'plot.default'. col: color for the lines drawn. lty: line type for the lines drawn. lwd: line width for the lines drawn. add: logical. If 'TRUE', add to a current plot. ...: additional arguments to 'plot.window', 'title', 'Axis' and 'box', typically graphical parameters such as 'cex.axis'. _D_e_t_a_i_l_s: 'contour' is a generic function with only a default method in base R. The methods for positioning the labels on contours are '"simple"' (draw at the edge of the plot, overlaying the contour line), '"edge"' (draw at the edge of the plot, embedded in the contour line, with no labels overlapping) and '"flattest"' (draw on the flattest section of the contour, embedded in the contour line, with no labels overlapping). The second and third may not draw a label on every contour line. For information about vector fonts, see the help for 'text' and 'Hershey'. Notice that 'contour' interprets the 'z' matrix as a table of 'f(x[i], y[j])' values, so that the x axis corresponds to row number and the y axis to column number, with column 1 at the bottom, i.e. a 90 degree clockwise rotation of the conventional textual layout. Alternatively, use 'contourplot' from the 'lattice' package where the 'formula' notation allows to use vectors 'x,y,z' of the same length. There is limited control over the axes and frame as arguments 'col', 'lwd' and 'lty' refer to the contour lines (rather than being general graphical parameters). For more control, add contours to a plot, or add axes and frame to a contour plot. _R_e_f_e_r_e_n_c_e_s: Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S Language_. Wadsworth & Brooks/Cole. _S_e_e _A_l_s_o: 'options("max.contour.segments")' for the maximal complexity of a single contour line. 'contourLines', 'filled.contour' for color-filled contours, 'contourplot' (and 'levelplot') from package 'lattice'. Further, 'image' and the graphics demo which can be invoked as 'demo(graphics)'. _E_x_a_m_p_l_e_s: require(grDevices) # for colours x <- -6:16 op <- par(mfrow = c(2, 2)) contour(outer(x, x), method = "edge", vfont = c("sans serif", "plain")) z <- outer(x, sqrt(abs(x)), FUN = "/") image(x, x, z) contour(x, x, z, col = "pink", add = TRUE, method = "edge", vfont = c("sans serif", "plain")) contour(x, x, z, ylim = c(1, 6), method = "simple", labcex = 1) contour(x, x, z, ylim = c(-6, 6), nlev = 20, lty = 2, method = "simple") 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), drawlabels = FALSE, axes = FALSE, frame = TRUE) 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); 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, vfont = c("sans serif", "plain")) 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) ## contourLines produces the same contour lines as contour line.list <- contourLines(x, y, volcano) 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, vfont = c("sans serif", "plain")) templines <- function(clines) { lines(clines[[2]], clines[[3]]) } invisible(lapply(line.list, templines)) par(opar)