levelplot {lattice}R Documentation

Level Plots

Description

Draw Level Plots and Contour plots.

Usage

levelplot(formula,
          at,
          col.regions = trellis.par.get("regions")$col,
          colorkey = region,
          contour = FALSE,
          cuts = 15,
          labels = format(at),
          pretty = FALSE,
          region = TRUE,
          ...)
contourplot(formula, at,
            contour = TRUE,
            cuts = 7,
            pretty = TRUE,
            ...)

Arguments

formula a formula of the form z ~ x * y | g1 * g2 * ..., where z is a numeric response, and x, y are numeric values evaluated on a rectangular grid.
g1,g2,..., if present, must be either factors or shingles.
Calculations are based on the assumption that all x and y values are evaluated on a grid (defined by (unique(x)) and (unique(y)). The function will not return an error if this is not true, but the display might be nonsense.
However, the x and y values need not be equally spaced. See example below with log scales.
As an extension to partially support the form used in filled.contour and image, formula can be a matrix.
at numeric vector giving breaks along the range of z. Contours (if any) will be drawn at these heights, and the regions in between would be colored using col.regions.
col.regions color vector to be used if regions is TRUE
colorkey logical specifying whether a color key is to be drawn alongside the plot, or a list describing the color key. The list may contain the following components:
space location of the colorkey, can be one of ``left'', ``right'', ``top'' and ``bottom''. Defaults to ``right''.
x,y location, unused
col vector of colors
at numeric vector specifying where the colors change. must be of length 1 more than the col vector.
labels a character vector for labelling the at values, or more commonly, a list of components labels, at, cex, col, font describing label positions.
tick.number approximate number of ticks.
corner interacts with x, y; unimplemented
width width of the key in terms of character widths
height length of key w.r.t side of plot.
contour logical, whether to draw contour lines.
cuts number of levels the range of z would be divided into
labels character vector of labels for contour lines, not implemented yet.
pretty logical, whether to use pretty labels
region logical, whether regions between contour lines should be filled
... other arguments

Details

These and all other high level Trellis functions have several arguments in common. These are extensively documented only in the help page for xyplot, which should be consulted to learn more detailed usage.

Author(s)

Deepayan Sarkar deepayan@stat.wisc.edu

See Also

xyplot, Lattice, panel.levelplot

Examples

x <- seq(pi/4, 5*pi, length = 100)
y <- seq(pi/4, 5*pi, length = 100)
r <- sqrt(outer(x^2, y^2, "+"))
grid <- expand.grid(x=x, y=y)
grid$z <- cos(r^2) * exp(-r/(pi^3))
levelplot(z~x*y, grid, cuts = 50, xlab="", ylab="",
          main="Weird Function", colorkey = FALSE)
levelplot(z~x*y, grid, cuts = 50, scales=list(log="e"), xlab="",
          ylab="", main="Weird Function", sub="with log scales",
          colorkey = FALSE, region = TRUE)
#S+ example
data(environmental)
attach(environmental)
ozo.m <- loess((ozone^(1/3)) ~ wind * temperature * radiation,
       parametric = c("radiation", "wind"), span = 1, degree = 2)
w.marginal <- seq(min(wind), max(wind), length = 50)
t.marginal <- seq(min(temperature), max(temperature), length = 50)
r.marginal <- seq(min(radiation), max(radiation), length = 4)
wtr.marginal <- list(wind = w.marginal, temperature = t.marginal,
        radiation = r.marginal)
grid <- expand.grid(wtr.marginal)
grid[, "fit"] <- c(predict(ozo.m, grid))
contourplot(fit ~ wind * temperature | radiation, data = grid,
          cuts = 10, region = TRUE,
          xlab = "Wind Speed (mph)",
          ylab = "Temperature (F)",
          main = "Cube Root Ozone (cube root ppb)",
          col.regions = trellis.par.get("regions")$col)
detach()

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