levelplot {lattice}  R Documentation 
Draw Level Plots and Contour plots.
levelplot(formula, data, at, contour = FALSE, cuts = 15, pretty = FALSE, region = TRUE, ..., col.regions = trellis.par.get("regions")$col, colorkey = region) contourplot(formula, data, at, contour = TRUE, labels = format(at), cuts = 7, pretty = TRUE, ...)
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, ...
are optional conditional variables, and must be either factors or
shingles if present.
Calculations are based on the assumption that all x and y values are evaluated on a grid (defined by their unique values). The function will not return an error if this is not true, but the display might not be meaningful. However, the x and y values need not be equally spaced. As an extension to partially support the form used in filled.contour and image , formula can be a
matrix.

data 
optional data frame in which variables are to be evaluated 
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. The general idea is that this should be a color vector of moderately large length (longer than the number of regions. By default this is 100). It is expected that this vector would be gradually varying in color (so that nearby colors would be similar). When the colors are actually chosen, they are chosen to be equally spaced along this vector. When there are more regions than col.regions, the colors are recycled. 
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:

contour 
logical, whether to draw contour lines. 
cuts 
number of levels the range of z would be divided into

labels 
logical specifying whether contour lines should be labelled, or
character vector of labels for contour lines. The type of labelling
can be controlled by the label.style argument, which is
passed on to panel.levelplot

pretty 
logical, whether to use pretty cut locations and labels 
region 
logical, whether regions between contour lines should be filled 
... 
other arguments 
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.
Other useful arguments are mentioned in the help page for the default
panel function panel.levelplot
(these are formally
arguments to the panel function, but can be specified in the high
level calls directly).
An object of class ``trellis''. The `update' method can be used to update components of the object and the `print' method (usually called by default) will plot it on an appropriate plotting device.
Deepayan Sarkar Deepayan.Sarkar@Rproject.org
xyplot
, Lattice
,
panel.levelplot
x < seq(pi/4, 5 * pi, length = 100) y < seq(pi/4, 5 * pi, length = 100) r < as.vector(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, scales=list(log="e"), xlab="", ylab="", main="Weird Function", sub="with log scales", colorkey = FALSE, region = TRUE) #SPLUS example require(stats) 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)") detach()