Message-ID: <OF7B7F749C.92CC1311-ON882573B0.0074D4A6-882573B0.007540B8@fs.fed.us>
Date: 2007-12-13T21:20:42Z
From: Seth W Bigelow
Subject: Overlaying trellis xyplot on contourplot
In-Reply-To: <eb555e660712131252i17bfb18dg927f3e94888fe9ff@mail.gmail.com>
Deepayan:
Very nice, thanks for introducing me to a new resource. I will include the
entire, functioning example in the event others may find it useful.
--Seth
###### Sample code for overlaying data points on a contour graph, using
xyplot and contourplot ##################
library(lattice)
model <- function(a,b,c,X1,X2) # provide model function for
contour plot
{(exp(a + b*X1 + c*X2)) / (1 + exp(a + b*X1 + c*X2))}
g <- expand.grid(X1 = seq(0.38, 0.8,0.01), X2 = seq(0.03,0.99,0.03)) #
create gridded data for contour plot
a <- -37.61 # Assign value to 'a' parameter
b <- 34.88 # Assign value to 'b' parameter
c <- 28.44 # Assign value to 'c' parameter
g$z<- model(a, b, c, g$X1,g$X2) # Create variable z using gridded
data, model, and variables
# Data to superimpose as xyplot on the contourplot....
ph <-c(0.42,0.47,0.59,0.40) # Create a vector of values under
variable 'ph'
phh <-c(0.76,0.81,0.82,0.71) # Create vector of values for
variable 'phh'
d <- data.frame(ph,phh) # Group variables ph & phh in
data frame 'd'
contourplot(z ~ X1 * X2,
data=g,
contour=TRUE,
xlim=c(0.38,0.8), ylim=c(0.401,0.999), zlim=c(0,1), # Set Axis Ranges
xlab="p(H)", ylab="p(H|H)", # Set axis labels
region = TRUE,
cuts=10,
panel = function(x,y,subscripts,...){
panel.contourplot(x,y,subscripts,...)
panel.xyplot(d$ph,d$phh)}
)
#### End ##############################