xyplot(lat ~ long | cut(depth, 2), data = quakes)

xyplot(lat ~ long | cut(depth, 3), data = quakes, 
       aspect = "iso", pch = ".", cex = 2, type = c("p", "g"),
       xlab = "Longitude", ylab = "Latitude", 
       strip = strip.custom(strip.names = TRUE, var.name = "Depth"))

xyplot(lat ~ long, data = quakes, aspect = "iso",
       groups = cut(depth, breaks = quantile(depth, ppoints(4, 1))), 
       auto.key = list(columns = 3, title = "Depth"), 
       xlab = "Longitude", ylab = "Latitude")

depth.col <- gray.colors(100)[cut(quakes$depth, 100, label = FALSE)]
depth.ord <- rev(order(quakes$depth))

xyplot(lat ~ long, data = quakes[depth.ord, ], 
       aspect = "iso", type = c("p", "g"), col = "black",
       pch = 21, fill = depth.col[depth.ord], cex = 2,
       xlab = "Longitude", ylab = "Latitude")

quakes$Magnitude <- equal.count(quakes$mag, 4)
summary(quakes$Magnitude)
quakes$color <- depth.col
quakes.ordered <- quakes[depth.ord, ]

xyplot(lat ~ long | Magnitude, data = quakes.ordered, col = "black",
       aspect = "iso", fill.color = quakes.ordered$color, cex = 2,
       panel = function(x, y, fill.color, ..., subscripts) {
           fill <- fill.color[subscripts]
           panel.grid(h = -1, v = -1)
           panel.xyplot(x, y, pch = 21, fill = fill, ...)
       },
       xlab = "Longitude", ylab = "Latitude")

depth.breaks <- do.breaks(range(quakes.ordered$depth), 50)
quakes.ordered$color <- 
    level.colors(quakes.ordered$depth, at = depth.breaks, 
                 col.regions = gray.colors)

xyplot(lat ~ long | Magnitude, data = quakes.ordered, 
       aspect = "iso", groups = color, cex = 2, col = "black",
       panel = function(x, y, groups, ..., subscripts) {
           fill <- groups[subscripts]
           panel.grid(h = -1, v = -1)
           panel.xyplot(x, y, pch = 21, fill = fill, ...)
       },
       legend = 
       list(right = 
            list(fun = draw.colorkey,
                 args = list(key = list(col = gray.colors,
                                        at = depth.breaks), 
                             draw = FALSE))),
       xlab = "Longitude", ylab = "Latitude")

types.plain <- c("p", "l", "o", "r", "g", "s", "S", "h", "a", "smooth")
types.horiz <- c("s", "S", "h", "a", "smooth")
horiz <- rep(c(FALSE, TRUE), c(length(types.plain), length(types.horiz)))
types <- c(types.plain, types.horiz)
set.seed(2007041)
x <- sample(seq(-10, 10, length = 15), 30, TRUE)
y <- x + 0.25 * (x + 1)^2 + rnorm(length(x), sd = 5)

xyplot(y ~ x | gl(1, length(types)),
       xlab = "type", 
       ylab = list(c("horizontal=TRUE", "horizontal=FALSE"), y = c(1/6, 4/6)),
       as.table = TRUE, layout = c(5, 3),
       between = list(y = c(0, 1)),
       strip = function(...) {
           panel.fill(trellis.par.get("strip.background")$col[1])
           type <- types[panel.number()]
           grid.text(lab = sprintf('"%s"', type), 
                     x = 0.5, y = 0.5)
           grid.rect()
       },
       scales = list(alternating = c(0, 2), tck = c(0, 0.7), draw = FALSE),
       par.settings = 
       list(layout.widths = list(strip.left = c(1, 0, 0, 0, 0))),
       panel = function(...) {
           type <- types[panel.number()]
           horizontal <- horiz[panel.number()]
           panel.xyplot(..., 
                        type = type,
                        horizontal = horizontal)
       })[rep(1, length(types))]