mapplot | R Documentation |
Produces Trellis displays of numeric (and eventually categorical) data on a map. This is largely meant as a demonstration, and users looking for serious map drawing capabilities should look elsewhere (see below).
mapplot(x, data, ...) ## S3 method for class 'formula' mapplot(x, data, map, outer = TRUE, prepanel = prepanel.mapplot, panel = panel.mapplot, aspect = "iso", legend = NULL, breaks, cuts = 30, colramp = colorRampPalette(hcl.colors(n = 11, palette = "Spectral")), colorkey = TRUE, ...) prepanel.mapplot(x, y, map, ...) panel.mapplot(x, y, map, breaks, colramp, exact = FALSE, lwd = 0.5, ...)
x, y |
For Suitable subsets (packets) of |
data |
A data source where names in the formula are evaluated |
map |
An object of class |
The remaining arguments are standard lattice arguments, relevant here mostly because they have different defaults than usual:
outer |
Logical flag specifying how variables separated by
|
prepanel |
The prepanel function. |
panel |
The panel function. |
aspect |
The aspect ratio. |
breaks, cuts, colramp |
controls conversion of numeric |
exact |
the default |
legend, colorkey |
controls legends; usually just a color key
giving the association between numeric values of |
lwd |
line width |
... |
Further arguments passed on to the underlying engine.
See |
An object of class "trellis"
.
This function is meant to demonstrate how maps can be incorporated in a Trellis display. Users seriously interested in geographical data should consider using software written by people who know what they are doing.
Deepayan Sarkar
https://en.wikipedia.org/wiki/Choropleth_map
Lattice
## Requires the 'maps' and 'mapproj' packages: if (require(maps) && require(mapproj)) { ## Note: Alaska, Hawaii and others are not included in county map; ## this generates warnings with both USCancerRates and ancestry. data(USCancerRates) suppressWarnings(print( mapplot(rownames(USCancerRates) ~ log(rate.male) + log(rate.female), data = USCancerRates, map = map("county", plot = FALSE, fill = TRUE, projection = "mercator")) )) suppressWarnings(print( mapplot(rownames(USCancerRates) ~ log(rate.male) + log(rate.female), data = USCancerRates, map = map("county", plot = FALSE, fill = TRUE, projection = "tetra"), scales = list(draw = FALSE)) )) data(ancestry) county.map <- map('county', plot = FALSE, fill = TRUE, projection = "azequalarea") ## set a sequential color palette as current theme, and use it opar <- trellis.par.get() trellis.par.set(custom.theme(region = rev(hcl.colors(9, "Purp")), alpha.line = 0.5)) suppressWarnings(print( mapplot(county ~ log10(population), ancestry, map = county.map, colramp = NULL, border = "transparent") )) trellis.par.set(opar) } ## Not run: ## this may take a while (should get better area records) if (require(maps) && require(mapproj)) { county.areas <- area.map(county.map, regions = county.map$names, sqmi = FALSE) ancestry$density <- with(ancestry, population / county.areas[as.character(county)]) mapplot(county ~ log(density), ancestry, map = county.map, border = NA, colramp = colorRampPalette(c("white", "black"))) } ## End(Not run)
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