trmat.G {GRASS} | R Documentation |
A wrapper for trmat()
from the spatial
package in the VR bundle, using the metadata of the underlying GRASS LOCATION.
trmat.G(G, obj, east=NULL, north=NULL)
G |
GRASS metadata from gmeta() |
obj |
object returned by surf.ls or surf.gls |
east |
see help(east) |
north |
see help(north) |
A vector of G$Ncells
values is returned, with the results of interpolation ordered as a GRASS raster file.
The functions in this package are intended to work with the GRASS geographical information system. The examples for wrapper functions will will work whether or not R is running in GRASS, and whether or not the current location is that of the data set used for the examples. Examples of interface functions will however (from version 0.2-2) only work outside GRASS, to avoid possible overwriting of GRASS database locations and/or files.
Original trmat()
: Brian D. Ripley and Bill Venables as detailed in the spatial package documentation; adapted by Roger S. Bivand, e-mail: Roger.Bivand@nhh.no.
http://grass.itc.it/statsgrass/index.html, Bivand, R. S., (2000) Using the R statistical data analysis language on GRASS 5.0 GIS data base files. Computers and Geosciences, 26, pp. 1043-1052; Unwin, D. J., Wrigley, N. (1987) Towards a general-theory of control point distribution effects in trend surface models. Computers and Geosciences, 13, pp. 351-355.
data(utm.maas) G <- maas.metadata if(G$Ncells != length(maasmask)) stop("example not running in Maas GRASS location") require(spatial) s1 <- surf.ls(1, utm.maas$east, utm.maas$north, utm.maas$Zn) s2 <- surf.ls(2, utm.maas$east, utm.maas$north, utm.maas$Zn) s3 <- surf.ls(3, utm.maas$east, utm.maas$north, utm.maas$Zn) s4 <- surf.ls(4, utm.maas$east, utm.maas$north, utm.maas$Zn) summary(s2) summary(s3) summary(s4) anova(s2,s3,s4) plot(G, trmat.G(G, s3)*maasmask, breaks=c(-10000, seq(-100, 1500, 200), 10000), col=c("yellow", grey(8:1/8), "red")) plot(G, ifelse(is.na(maasmask), 1, NA), breaks=c(0,2), col="wheat", add=TRUE) plot(s3, add=TRUE) legend(c(269900, 270600), c(5652000, 5652900), bty="n", bg="wheat", legend=c("> 1500", rev(legtext(seq(-100,1500,200))), "< -100", "mask=NA"), fill=c("red", rev(grey(8:1/8)), "yellow", "wheat")) oldpar <- par(mfrow=c(2,2)) plot(G, trmat.G(G, s1)*maasmask, breaks=c(-10000, seq(-100, 1500, 200), 10000), col=c("yellow", grey(8:1/8), "red")) plot(G, ifelse(is.na(maasmask), 1, NA), breaks=c(0,2), col="wheat", add=TRUE) plot(s1, add=TRUE) plot(G, trmat.G(G, s2)*maasmask, breaks=c(-10000, seq(-100, 1500, 200), 10000), col=c("yellow", grey(8:1/8), "red")) plot(G, ifelse(is.na(maasmask), 1, NA), breaks=c(0,2), col="wheat", add=TRUE) plot(s2, add=TRUE) plot(G, trmat.G(G, s3)*maasmask, breaks=c(-10000, seq(-100, 1500, 200), 10000), col=c("yellow", grey(8:1/8), "red")) plot(G, ifelse(is.na(maasmask), 1, NA), breaks=c(0,2), col="wheat", add=TRUE) plot(s3, add=TRUE) plot(G, trmat.G(G, s4)*maasmask, breaks=c(-10000, seq(-100, 1500, 200), 10000), col=c("yellow", grey(8:1/8), "red")) plot(G, ifelse(is.na(maasmask), 1, NA), breaks=c(0,2), col="wheat", add=TRUE) plot(s4, add=TRUE) par(oldpar)