plot.grassmeta {GRASS}R Documentation

Equal scale plots for GRASS raster and site data

Description

plot.grassmeta provides a simple interface between grass data objects and the image() function; category layers may be plotted by taking unclass() of the layer, and setting zlim to non-default values. If layer is not set, a blank base map is plotted, for instance for use with points().

Usage

## S3 method for class 'grassmeta':
plot(x, layer=NULL, xlab="", ylab="", reverse=NULL, add=FALSE,
 breaks=NULL, ...)
legtext(break.levels)
leglabs(x1, under="under", over="over", between="-")

Arguments

x GRASS metadata from gmeta()
layer GRASS-ordered raster layer passed on to image()
xlab a title for the x axis, passed to plot()
ylab a title for the y axis, passed to plot()
reverse see help(reverse)
add FALSE for new plot, TRUE to overlay layer on prior plot
... parameters passed through to image()
break.levels vector of image break levels
breaks vector of image break levels
x1 in leglabs(), a vector of breaks
under character value to denote under
over character value to denote over
between character value to denote between

Details

The function uses asp=1 from the plot.window() function to ensure that the scales chosen to be equal on both axes, that is 1cm represents the same units on each. The legtext function is a small helper to aid in converting image break levels into legend texts, taking a numeric argument as image(break=), and returning a character vector.

Value

none

Note

The functions in this package are intended to work with the GRASS geographical information system. The examples for wrapper functions will will work whether or not R is running in GRASS, and whether or not the current location is that of the data set used for the examples. Examples of interface functions will however (from version 0.2-2) only work outside GRASS, to avoid possible overwriting of GRASS database locations and/or files.

Author(s)

Roger S. Bivand, e-mail: Roger.Bivand@nhh.no.

References

http://grass.itc.it/statsgrass/index.html, Bivand, R. S., (2000) Using the R statistical data analysis language on GRASS 5.0 GIS data base files. Computers and Geosciences, 26, pp. 1043-1052.

See Also

plot.window, image

Examples

data(utm.maas)
Zn.o <- as.ordered(cut(utm.maas$Zn, labels=c("insignificant", "low",
"medium", "high", "crisis"), breaks=c(100, 200, 400, 700, 1000, 2000), 
include.lowest=TRUE))
G <- maas.metadata
plot(G)
points(utm.maas$east, utm.maas$north, pch=unclass(Zn.o))
legend(x=c(269800, 270500), y=c(5652300, 5653000), pch=c(1:5),
legend=levels(Zn.o))
title("Note equal east and north scales")
example(kde2d.G)

[Package GRASS version 0.3-7 Index]