[R] Lattice: Plotting two densities on the same plot(s)?

Olivia Lau olau at fas.harvard.edu
Wed Jan 8 04:46:02 CET 2003

I am trying to plot two density lines on the same graph.  Using the
functions on the base package, I would go:

plot(density(x), col = 1)
lines(density(y), col = 2)

And I get two distinct (one-bump) density lines.  When I try to do it
using lattice, I get two two-humped lines.  (In other words, I think the
smoothing function is taking the next set of data points and smoothing them
in the same function as the prior set.)




democrat <- rnorm(100, 0.3, 0.1)
republican <- rnorm(100, 0.5, 0.1)
state <- c("Delaware")
temp1 <- as.data.frame(cbind(state, democrat, republican))

democrat <- rnorm(100, 0.5, 0.1)
republican <- rnorm(100, 0.7, 0.1)
state <- c("Pennsylvania")
temp2 <- as.data.frame(cbind(state, democrat, republican))

data1 <- rbind(temp1, temp2)

What I'm doing right now is:

densityplot(~ democrat | state, data = data1,
  xlim = c(0, 1), ylim = c(0, 10),
  panel = function(x) {
  panel.densityplot(republican,  col = "red")
  panel.densityplot(democrat, col = "black")

What should I do to draw two separate density plots on the same lattice


Olivia Lau

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