Package 'rasterImage'

Defines a color palette

Description

This function defines a color palette and returns a vector of colors. The palettes itself are adapted from the ColorBrewer project.

Usage

colorPalette(n = NULL, type = "spectral", inv = F)

Arguments

n	number of colors to produce
type	sets the type of color palette. See Details
inv	revert the order of colors

Details

The parameter type controls the output palette type as follows:

"spectral"

spectral colors from blue to red

"specrtalHalf"

spectral colors from green to red

"green"

MultiHue yellow - green

"blue"

MultiHue yellow - green blue

"orange"

MultiHue yellow - orange - brown

"red"

MultiHue yellow - orange red

"red-white-bule","bwr"

red - white - blue colors

"rainbow"

reproduces the rainbow color set

"black-white","bw"

gray scale colors

"white-black","wb"

gray scale colors from white to black

"jet.colors","jc"

dark blue to dark red

"hzdr1"

HZDR cooperate design colors

"hzdr2"

HZDR cooperate design colors

If a vector of color names is supported, then a customized palette will be calculated according to these colors.

Value

returns a vector of colors to be passed to image or rasterImage

References

http://colorbrewer2.org by Cynthia A. Brewer, Geography, Pennsylvania State University

Examples

# default "spectral" palette
barplot(rep(1,10), col = colorPalette(10))

# custom color palette
barplot(rep(1,10), col = colorPalette(n = 10, type = c("red","blue","yellow")))

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Plotting a raster image with axis and color legend

Description

The function is a wrapper for the image() function, but with a comfortable control of the z-axis and its color legend. The wrapper also supports image resizing (resolution) and png output for better export.

Usage

rasterImage2(x = NULL, y = NULL, z, zlim = NULL, xlim = NULL,
  ylim = NULL, dim.max = NULL, plot.zero.line = T, regularGrid = T,
  zlab = NULL, z.cex = 0.5, z.adj = c(0.5, 0.5), z.format = "fg",
  ndz = 7, ncolors = 256, palette = "spectral", palette.inv = F,
  ...)

Arguments

x	x-axis vector corresponding to the z-matrix
y	y-axis vector corresponding to the z-matrix
z	numeric matrix to be plotted
zlim	sets the range of the color coded z-axis
xlim	the x limits (x1, x2) of the plot. Note that x1 > x2 is allowed and leads to a ‘reversed axis’. The default value, NULL, indicates that the range of the finite values to be plotted should be used.
ylim	the y limits of the plot.
dim.max	defines the dimensions of the visible area of z. It automatically invokes a rescale. In case of large data sets this parameter can improve plotting speed.
plot.zero.line	logical, if a line at x = 0 and y = 0 is to be plotted.
regularGrid	logical, if FALSE then a vector plot is generated, which is the slow and standard behaviour of image. If this parameter is TRUE then a raster image is generated, which can be processed much faster, compared to the FALSE option.
zlab	defines the z-label
z.cex	cex value for the z-label. It sets the font size in relation to the global par()$cex value
z.adj	a two component vector. It sets the left/right and top/bottom justification
z.format	controls how the numbers besides the color scale are composed. It works like the format option of formatC
ndz	sets the axis breaks right to the color scale
ncolors	number of colors to use in the plot
palette	defines the color palette to be used in the plot
palette.inv	logical, if TRUE reverts the color palette
...	further arguments to the plot function, e.g. 'xlab'

Details

The regularGrid option forces interpolation in case of irregular spacing of x or y. All data is then projected on a regular grid. This correction invokes a spline interpolation. Missing NA values are ignored.

Examples

rasterImage2( z = volcano, palette = "spectral", dim.max = c(500,100)
             ,zlab = "Height", z.adj = c(0,1) ,z.cex = 1
             ,main = "Volcano Data Set"
           )

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