R: Panel Functions for levelplot and contourplot

F_1_panel.levelplot {lattice} | R Documentation

## 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$lwd,
                    border = "transparent",
                    border.lty = 1,
                    border.lwd = 0.1,
                    ...,
                    col.regions = regions$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.
`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.

### 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.

### Author(s)

Deepayan Sarkar Deepayan.Sarkar@R-project.org

### See Also

`levelplot`, `level.colors`, `contourLines`

### Examples

    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 = topo.colors, cuts = 30, interpolate = TRUE)

[Package lattice version 0.20-6 Index]