surf.ls
.
trls.influence(object) plot.trls(x, border = 1, col = NA, pch = 4, cex = 0.6, add = F, div = 8, ...)
surf.ls
plot.trls
TRUE
trls.influence
returns a list with:
residuals.trls
Unwin, D. J., Wrigley, N. (1987) Towards a general-theory of control point distribution effects in trend surface models. Computers and Geosciences, 13, 351-355.
library(MASS) topo2 <- surf.ls(2, topo) infl.topo2 <- trls.influence(topo2) cand <- as.data.frame(infl.topo2)[abs(infl.topo2$stresid) > 1.5,] cand cand.xy <- topo[as.integer(dimnames(cand)[[1]]), c("x", "y")] trsurf <- trmat(topo2, 0, 6.5, 0, 6.5, 50) eqscplot(trsurf, type="n") #under S need to choose appropriate colour numbers contour(trsurf, add=T, col="grey") plot(topo2, add=T, div=3) points(cand.xy, pch=16, col="orange")