raster (version 1.9-1)

plot: Plot a Raster* object

Description

Plot (that is, make a map of) the values of a Raster* object, or make a scatterplot of their values. Points, lines, and polygons can be drawn on top of a map using plot(..., add=TRUE), or functions like points, lines, polygons text plots a textual (rather than color) representation of values of the cells on top of the cells.

Methods

x=RasterLayer plot(x, col=rev(terrain.colors(25)), maxpixels=100000, axes = TRUE, xlab="", ylab="", alpha=1, ...) rll{ x a RasterLayer object col A color palette, i.e. a vector of n contiguous colors such as rainbow, heat.colors, and topo.colors, or one or your own making, perhaps using colorRampPalette maxpixels Maximum number of pixels used for the map alpha Number between 0 and 1 to set transparancy. 0 is entirely transparant, 1 is not transparant ... Any argument that can be passed to image.plot and to plot } If x has a 'Color table', the default all to plot is: plot(x, maxpixels=500000, ext=NULL, interpolate=FALSE, axes=FALSE, xlab="", ylab="", ...) rll{ ext An extent object to zoom in a region interpolate Logical. Should the image be interpolated? axes Logical. Should axes be drawn? addfun Function. functions adding additional items such as points or polygons to the plot (map). Typically containing statements like points(xy); plot(polygons, add=TRUE). This is particularly useful to add something to each map when plotting a multi-layer Raster* object. ... Graphical parameters } x=RasterStack or RasterBrick, y=numeric or missing plot(x, col=rev(terrain.colors(25)), subsample=TRUE, maxpixels=100000, alpha=1, axes=TRUE, xlab="", ylab="", ...) rll{ x a RasterStack or RasterBrick object y The index of a RasterLayer in a RasterStack to be plotted. Either a single number between 1 and nlayers(rstack), a vector of numbers, or missing. If y is missing, all RasterLayers in the RasterStack will be plotted (up to a maximum of 16). other arguments See above } x=Raster, y=Raster Produces a scatter plot of the values of x against those of y. plot(x, y, maxpixels=100000, cex=0.1, ...) rll{ x a RasterLayer object y a RasterLayer object maxpixels Maximum number of pixels in the map display cex point size ... Any argument that can be passed to plot } x=Extent, y="ANY" Draws the (rectangular) bounding box of a raster object. plot(ext) rll{ ext a Extent object }

Details

Most of the code for this function was taken from image.plot (fields package). Raster objects with a color-table (e.g. a graphics file) will be plotted according to the color table.

See Also

spplot, plotRGB, persp, contour, pairs, hist The rasterVis package has more advanced plotting methods for Raster* objects.

Examples

# RasterLayer
r <- raster(nrows=10, ncols=10)
r <- setValues(r, 1:ncell(r))
plot(r)
text(r)

e <- extent(r)
plot(e, add=TRUE, col='red', lwd=4)
e <- e / 2
plot(e, add=TRUE, col='red')


# Scatterplot of 2 RasterLayers
r2 <- sqrt(r)
plot(r, r2)

# Multi-layer object (RasterStack / Brick)
s <- stack(r, r2, r/r)
plot(s, 2)
plot(s)

# two objects, different range, one scale:
r[] <- runif(ncell(r))
r2 <- r/2
brks <- seq(0, 1, by=0.1) 
nb <- length(brks)-1 
par(mfrow=c(1,2))
plot(r, breaks=brks, col=rev(terrain.colors(nb)), lab.breaks=brks, zlim=c(0,1)) 
plot(r2, breaks=brks, col=rev(terrain.colors(nb)), lab.breaks=brks, zlim=c(0,1)) 


# breaks and labels
x <- raster(nc=10, nr=10)
x[] <- runif(ncell(x))
brk <- c(0, 0.25, 0.75, 1)
arg <- list(at=c(0.12,0.5,0.87), labels=c("Low","Med.","High"))
plot(x, col=terrain.colors(3), breaks=brk)
plot(x, col=terrain.colors(3), breaks=brk, axis.args=arg)
par(mfrow=c(1,1))

# color ramp
plot(x, col=colorRampPalette(c("red", "white", "blue"))(255))

# adding random points to the map
xy <- cbind(-180 + runif(10) * 360, -90 + runif(10) * 180)
points(xy, pch=3, cex=5)

# for SpatialPolygons do
# plot(pols, add=TRUE)

# adding random points to each map of each layer of a RasterStack
fun <- function() {
	points(xy, cex=2)
	points(xy, pch=3, col='red')
}
plot(s, addfun=fun)