Create a bubble plot of spatial data

Create a bubble plot of spatial data, with options for bicolour residual plots (xyplot wrapper)

bubble(obj, zcol = 1, ..., fill = TRUE, maxsize = 3, do.sqrt = TRUE, pch,
        col = c("#d01c8b", "#4dac26"), key.entries = quantile(data[,zcol]), main,
        identify = FALSE, labels = row.names(data.frame(obj)), key.space = "right",
        scales = list(draw = FALSE), xlab = NULL, ylab = NULL, panel = panel.bubble,
        sp.layout = NULL,
        xlim = bbexpand(bbox(obj)[1,], 0.04),
        ylim = bbexpand(bbox(obj)[2,], 0.04))

Arguments

obj

object of, or extending, class SpatialPointsDataFrame or SpatialGridDataFrame, see coordinates or SpatialPointsDataFrame; the object knows about its spatial coordinates
zcol

z-variable column name, or column number after removing spatial coordinates from x@data: 1 refers to the first non-coordinate column
fill

logical; if TRUE, filled circles are plotted (pch = 16), else open circles (pch = 1); the pch argument overrides this
maxsize

cex value for largest circle
do.sqrt

logical; if TRUE the plotting symbol area (sqrt(diameter)) is proportional to the value of the z-variable; if FALSE, the symbol size (diameter) is proportional to the z-variable
pch

plotting character
col

colours to be used; numeric vector of size two: first value is for negative values, second for positive values. Default colors: 5-class PiYG from colorbrewer.org.
key.entries

the values that will be plotted in the key; by default the five quantiles min, q.25, median q.75, max
main

main plotting title
identify

logical; if true, regular plot is called instead of xyplot, and followed by a call to identify().
labels

labels argument passed to plot if identify is TRUE
...

arguments, passed to xyplot, or plot if identification is required.
key.space

location of the key
scales

scales argument as passed to xyplot
xlab

x-axis label
ylab

y-axis label
panel

panel function used
sp.layout

possible layout items; see spplot
xlim

x axis limit
ylim

y axis limit

Value

returns (or plots) the bubble plot; if identify is TRUE, returns the indexes (row numbers) of identified points.

See also

xyplot, mapasp, identify

Examples

data(meuse)
coordinates(meuse) <- c("x", "y") # promote to SpatialPointsDataFrame
bubble(meuse, "cadmium", maxsize = 2.5, main = "cadmium concentrations (ppm)",
    key.entries = 2^(-1:4))
bubble(meuse, "zinc", main = "zinc concentrations (ppm)",
    key.entries =  100 * 2^(0:4))