Contouring

# interpolate and contour Oregon station data
library(akima)
attach(ortann)
tann.interp <- interp(longitude, latitude, tann,
xo= seq(-124.5000, -116.8333, .1667), yo= seq(42.0000, 46.1667, .0833))
image(tann.interp)
contour(tann.interp, xlab="", ylab="", add=T)
points(longitude, latitude)

# Delaunay triangulation (deldir requires library deldir)
library(deldir)
deldir(longitude, latitude, plot=T, add=T)

# interpolation grid
interpgrid.margin <- list(longitude=seq(-124.5000, -116.8333, .1667), latitude=seq(42.0000, 46.1667, .0833))
interpgrid <- expand.grid(interpgrid.margin)
points(interpgrid$longitude, interpgrid$latitude, pch=3, cex=.5)

 

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