drawPalette {oce} | R Documentation

## Draw a palette, leaving margins suitable for accompanying plot

### Description

Draw a palette, leaving margins suitable for accompanying plot.

### Usage

    drawPalette(zlim, zlab = "", breaks, col, colormap, mai,
      cex.axis = par("cex.axis"), pos = 4, labels = NULL, at = NULL, levels,
      drawContours = FALSE, plot = TRUE, fullpage = FALSE,
      drawTriangles = FALSE, axisPalette, tformat,
      debug = getOption("oceDebug"), ...)

### Arguments

`zlim` | two-element vector containing the lower and upper limits of z. This may also be a vector of any length exceeding 1, in which case its range is used.
`zlab` | label for the palette scale.
`breaks` | the z values for breaks in the colour scheme.
`col` | either a vector of colours corresponding to the breaks, of length 1 less than the number of breaks, or a function specifying colours, e.g. `oce.colorsJet` for a rainbow.
`colormap` | a colour map as created by `colormap`. If provided, this takes precedence over `breaks` and `col`.
`mai` | margins for palette, as defined in the usual way; see `par`. If not given, reasonable values are inferred from the existence of a non-blank `zlab`.
`cex.axis` | character-expansion value for text labels
`pos` | an integer indicating the location of the palette within the plotting area, 1 for near the bottom, 2 for near the left-hand side, 3 for near the top side, and 4 (the default) for near the right-hand side.
`labels` | optional vector of labels for ticks on palette axis (must correspond with `at`)
`at` | optional vector of positions for the `label`s
`levels` | optional contour levels, in preference to `breaks` values, to be added to the image if `drawContours` is `TRUE`.
`drawContours` | logical value indicating whether to draw contours on the palette, at the colour breaks.
`plot` | logical value indicating whether to plot the palette, the default, or whether to just alter the margins to make space for where the palette would have gone. The latter case may be useful in lining up plots, as in example 1 of “Examples”.
`fullpage` | logical value indicating whether to draw the palette filling the whole plot width (apart from `mai`, of course). This can be helpful if the palette panel is to be created with `layout`, as illustrated in the “Examples”.
`drawTriangles` | logical value indicating whether to draw triangles on the top and bottom of the palette. If a single value is provide, it applies to both ends of the palette. If a pair is provided, the first refers to the lower range of the palette, and the second to the upper range.
`axisPalette` | optional replacement function for `axis()`, e.g. for exponential notation on large or small values.
`tformat` | optional format for axis labels, if the variable is a time type (ignored otherwise).
`debug` | a flag that turns on debugging. Set to 1 to get a moderate amount of debugging information, or to 2 to get more.
`...` | optional arguments passed to plotting functions.

### Details

In the normal use, `drawPalette` draws an image palette near the right-hand side of the plotting device, and then adjusts the global margin settings in such a way as to cause the next plot to appear (with much larger width) to the left of the palette. The function can also be used, if `zlim` is not provided, to adjust the margin without drawing anything; this is useful in lining up the x axes of a stack of plots, some some of which will have palettes and others not.

The plot positioning is done entirely with margins, not with `par(mfrow)` or other R schemes for multi-panel plots. This means that the user is free to use those schemes without worrying about nesting or conflicts.

### Value

None.

### Use with multi-panel plots

An important consequence of the margin adjustment is that multi-panel plots require that the initial margin be stored prior to the first call to `drawPalette`, and reset after each palette-plot pair. This method is illustrated in “Examples”.

### Author(s)

Dan Kelley, with help from Clark Richards

### See Also

This is used by `imagep`.

### Examples

    library(oce)
    par(mgp=getOption("oceMgp"))

    ## 1. A three-panel plot
    par(mfrow=c(3, 1), mar=c(3, 3, 1, 1))
    omar <- par('mar')                 # save initial margin

    ## 1a. top panel: simple case
    drawPalette(zlim=c(0, 1), col=oce.colorsJet(10))
    plot(1:10, 1:10, col=oce.colorsJet(10)[1:10],pch=20,cex=3,xlab='x', ylab='y')
    par(mar=omar)                      # reset margin

    ## 1b. middle panel: colormap
    cm <- colormap(name="gmt_globe")
    drawPalette(colormap=cm)
    icol <- seq_along(cm$col)
    plot(icol, cm$breaks[icol], pch=20, cex=2, col=cm$col,
         xlab="Palette index", ylab="Palette breaks")
    par(mar=omar)                      # reset margin

    ## 1c. bottom panel: space for palette (to line up graphs)
    drawPalette(plot=FALSE)
    plot(1:10, 1:10, col=oce.colorsJet(10)[1:10],pch=20,cex=3,xlab='x', ylab='y')
    par(mar=omar)                      # reset margin

    # 2. Use layout to mimic the action of imagep(), with the width
    # of the palette region being 14 percent of figure width.
    d <- 0.14
    layout(matrix(1:2,nrow=1), widths=c(1-d,d))
    image(volcano, col=oce.colorsJet(100), zlim=c(90, 200))
    contour(volcano, add=TRUE)
    drawPalette(c(90, 200), fullpage=TRUE, col=oce.colorsJet)

[Package oce version 0.9-22 Index]