rasterImage2 {rasterImage}

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"
           )