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Enhanced Contour Plots

Source: R/contourf.R
contourf.Rd

This is an enhancement to contour, written as a wrapper for that function. It creates a contour plot, or adds contour lines to an existing plot, allowing the contours to be filled and returning the list of contour lines.

Usage

contourf(
  x = seq(0, 1, length.out = nrow(z)),
  y = seq(0, 1, length.out = ncol(z)),
  z,
  nlevels = 10,
  levels = pretty(zlim, nlevels),
  zlim = range(z, finite = TRUE),
  col = par("fg"),
  color.palette = colorRampPalette(c("white", col)),
  fill.col = color.palette(nlevels + 1),
  fill.alpha = 0.5,
  add = FALSE,
  ...
)

Arguments

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 x$z this is used for z.

z

a matrix containing the values to be plotted (NAs 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

zlim

z-limits for the plot. x-limits and y-limits can be passed through ...

col

color for the lines drawn

color.palette

a color palette function to be used to assign fill colors in the plot

fill.col

a call to the color.palette function or an an explicit set of colors to be used in the plot. Use fill.col=NULL to suppress the filled polygons. a vector of fill colors corresponding to levels. By default, a set of possibly transparent colors is calculated ranging from white to col, using transparency given by fill.alpha

fill.alpha

transparency value for fill.col, either a hex character string, or a numeric value between 0 and 1. Use fill.alpha=NA to suppress transparency.

add

logical. If TRUE, add to a current plot.

...

additional arguments passed to contour, including all arguments of contour.default not mentioned above, as well as additional graphical parameters passed by contour.default to more basic functions.

Value

Returns invisibly the list of contours lines, with components levels, x, y. See contourLines.

See also

contour, contourLines

contourplot from package lattice.

Author

Michael Friendly

Examples


x <- 10*1:nrow(volcano)
y <- 10*1:ncol(volcano)
contourf(x,y,volcano, col="blue")

contourf(x,y,volcano, col="blue", nlevels=6)


# return value, unfilled, other graphic parameters
res <- contourf(x,y,volcano, col="blue", fill.col=NULL, lwd=2)

# levels used in the plot
sapply(res, function(x) x[[1]])
#>  [1] 100 100 100 110 110 110 110 120 130 140 150 150 160 160 170 170 170 180 180
#> [20] 190