## Constructing panel functions on the fly
EE <- equal.count(ethanol$E, number=9, overlap=1/4)
xyplot(NOx ~ C | EE, data = ethanol,
prepanel = function(x, y) prepanel.loess(x, y, span = 1),
xlab = "Compression ratio", ylab = "NOx (micrograms/J)",
panel = function(x, y) {
panel.grid(h=-1, v= 2)
panel.xyplot(x, y)
panel.loess(x,y, span=1)
},
aspect = "xy")
# Wireframe loess surface fit. See Figure 4.61 from Cleveland.
require(stats)
with(ethanol, {
eth.lo <- loess(NOx ~ C * E, span = 1/3, parametric = "C",
drop.square = "C", family="symmetric")
eth.marginal <- list(C = seq(min(C), max(C), length.out = 25),
E = seq(min(E), max(E), length.out = 25))
eth.grid <- expand.grid(eth.marginal)
eth.fit <- predict(eth.lo, eth.grid)
wireframe(eth.fit ~ eth.grid$C * eth.grid$E,
shade=TRUE,
screen = list(z = 40, x = -60, y=0),
distance = .1,
xlab = "C", ylab = "E", zlab = "NOx")
})
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