tileplot | R Documentation |
Represents an irregular set of (x, y) points with a color covariate. Polygons are drawn enclosing the area closest to each point. This is known variously as a Voronoi mosaic, a Dirichlet tesselation, or Thiessen polygons.
tileplot(x, data = NULL, aspect = "iso", prepanel = "prepanel.default.xyplot", panel = "panel.voronoi", ...)
x, data |
formula and data as in
|
aspect |
aspect ratio: "iso" is recommended as it reproduces the distances used in the triangulation calculations. |
panel, prepanel |
see |
... |
further arguments to the panel function, which defaults to
|
See panel.voronoi
for further options and details.
Felix Andrews felix@nfrac.org
panel.voronoi
, levelplot
xyz <- data.frame(x = rnorm(100), y = rnorm(100), z = rnorm(100)) tileplot(z ~ x * y, xyz) ## Alternative backend using 'deldir' package ## Not run: tileplot(z ~ x * y, xyz, backend = "deldir") ## End(Not run) ## showing rectangular window boundary tileplot(z ~ x * y, xyz, xlim = c(-2, 4), ylim = c(-2, 4)) ## insert some missing values xyz$z[1:10] <- NA ## the default na.rm = FALSE shows missing polygons tileplot(z ~ x * y, xyz, border = "black", col.regions = grey.colors(100), pch = ifelse(is.na(xyz$z), 4, 21), panel = function(...) { panel.fill("hotpink") panel.voronoi(...) }) ## use na.rm = TRUE to ignore points with missing values update(trellis.last.object(), na.rm = TRUE) ## a quick and dirty approximation to US state boundaries tmp <- state.center tmp$Income <- state.x77[,"Income"] tileplot(Income ~ x * y, tmp, border = "black", panel = function(x, y, ...) { panel.voronoi(x, y, ..., points = FALSE) panel.text(x, y, state.abb, cex = 0.6) })
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