Prepanel for ciplot

Usage

prepanel.ci(x, y, lower, upper, subscripts, groups = NULL, ...)

Arguments

x, y: x and y values, numeric or factor
lower: lower confidence limits
upper: upper confidence limits
groups, subscripts: See xyplot. Whenever appropriate, calculations are done separately for each group and then combined.
...: other arguments, usually ignored

Examples

mod <- lm(Petal.Width ~ Petal.Length * Species, data = iris)
newdat <- expand.grid(
  Petal.Length = seq(1, 7, by = 0.1),
  Species = c("setosa", "versicolor", "virginica")
)
pred <- predict(mod, newdat, interval = "confidence")
dd <- cbind(newdat, pred)

xyplot(
  fit ~ Petal.Length,
  groups = Species, data = dd,
  prepanel = prepanel.ci,
  ylab = "Petal Width",
  xlab = "Petal Length",
  lower = dd$lwr, upper = dd$upr, alpha = 0.3,
  panel = function(...) {
    panel.ci(..., grid = TRUE)
    panel.xyplot(type = "l", ...)
  }
)