F_1_panel.levelplot: Panel Functions for levelplot and contourplot

Description

These are the default panel functions for levelplot and contourplot. Also documented is an alternative raster-based panel function for use with levelplot.

Usage

panel.levelplot(x, y, z, 
                subscripts,
                at = pretty(z),
                shrink,
                labels,
                label.style = c("mixed", "flat", "align"),
                contour = FALSE,
                region = TRUE,
                col = add.line$col,
                lty = add.line$lty,
                lwd = add.line$lwd,
                border = "transparent",
                border.lty = 1,
                border.lwd = 0.1,
                ...,
                region.type = c("grid", "contour"),
                col.regions = regions$col,
                alpha.regions = regions$alpha,
                identifier = "levelplot")
panel.contourplot(...)
panel.levelplot.raster(x, y, z, 
                       subscripts,
                       at = pretty(z),
                       ...,
                       col.regions = regions$col,
                       alpha.regions = regions$alpha,
                       interpolate = FALSE,
                       identifier = "levelplot")

Arguments

x, y, z

Variables defining the plot.

subscripts

Integer vector indicating what subset of x, y and z to draw.

at

Numeric vector giving breakpoints along the range of z. See levelplot for details.

shrink

Either a numeric vector of length 2 (meant to work as both x and y components), or a list with components x and y which are numeric vectors of length 2. This allows the rectangles to be scaled proportional to the z-value. The specification can be made separately for widths (x) and heights (y). The elements of the length 2 numeric vector gives the minimum and maximum proportion of shrinkage (corresponding to min and max of z).

labels

Either a logical scalar indicating whether the labels are to be drawn, or a character or expression vector giving the labels associated with the at values. Alternatively, labels can be a list with the following components:

labels:: a character or expression vector giving the labels. This can be omitted, in which case the defaults will be used.

col, cex, alpha:

graphical parameters for label texts

fontfamily, fontface, font:

font used for the labels

label.style

Controls how label positions and rotation are determined. A value of "flat" causes the label to be positioned where the contour is flattest, and the label is not rotated. A value of "align" causes the label to be drawn as far from the boundaries as possible, and the label is rotated to align with the contour at that point. The default is to mix these approaches, preferring the flattest location unless it is too close to the boundaries.

contour

A logical flag, specifying whether contour lines should be drawn.

region

A logical flag, specifying whether inter-contour regions should be filled with appropriately colored rectangles.

col, lty, lwd

Graphical parameters for contour lines.

border

Border color for rectangles used when region=TRUE.

border.lty, border.lwd

Graphical parameters for the border

...

Extra parameters.

region.type

A character string, one of "grid" and "contour". The former (the default) uses a grid of rectangles to display the colors for the level plot; the latter uses a grid of polygons, mimicking the behavior of filled.contour, which gives a smoother appearance at the cost of increased processing time.

The "contour" option requires x and y to be complete, in the sense that it must include all possible combinations in the underlying grid. However, z values are allowed to be missing.

col.regions

A vector of colors, or a function to produce a vecor of colors, to be used if region=TRUE. Each interval defined by at is assigned a color, so the number of colors actually used is one less than the length of at. See level.colors for details on how the color assignment is done.

alpha.regions

numeric scalar controlling transparency of facets

interpolate

logical, passed to grid.raster.

identifier

A character string that is prepended to the names of grobs that are created by this panel function.

Author

Deepayan Sarkar Deepayan.Sarkar@R-project.org.

The functionality of region.type = "contour" is based on code borrowed from the gridGraphics package, written by Zhijian (Jason) Wen and Paul Murrell and ported to lattice by Johan Larsson.

Details

The same panel function is used for both levelplot and contourplot (which differ only in default values of some arguments). panel.contourplot is a simple wrapper to panel.levelplot.

When contour=TRUE, the contourLines function is used to calculate the contour lines.

panel.levelplot.raster is an alternative panel function that uses the raster drawing abilities in R 2.11.0 and higher (through grid.raster). It has fewer options (e.g., can only render data on an equispaced grid), but can be more efficient. When using panel.levelplot.raster, it may be desirable to render the color key in the same way. This is possible, but must be done separately; see levelplot for details.

Examples

Run this code


require(grid)

levelplot(rnorm(10) ~ 1:10 + sort(runif(10)), panel = panel.levelplot)

suppressWarnings(plot(levelplot(rnorm(10) ~ 1:10 + sort(runif(10)),
                                panel = panel.levelplot.raster,
                                interpolate = TRUE)))

levelplot(volcano, panel = panel.levelplot.raster)

levelplot(volcano, panel = panel.levelplot.raster,
          col.regions = hcl.colors, cuts = 30, interpolate = TRUE)