colourScale: Create colour scales

In mapmisc: Utilities for Producing Maps

Create colour scales

Description

Produces a scale of colours for plotting maps

Usage

	colourScale(x, breaks=5, style=c("quantile","equal","unique", "fixed"),
	 col="YlOrRd", opacity=1, dec=NULL, digits = 6, firstBreak=NULL, 
	 transform=NULL, revCol=FALSE, exclude=NULL, labels=NULL, ...)
	colorScale(...)
	breaksForRates(x, breaks = 10, transform = 0.1,
      multiples = c(2, 4, 5, 10)) 
	

Arguments

x	A vector or single-layer Raster, numeric or factor, for which a colour scale will be created
breaks	For colourScale either the number of or vector of breaks. for legendBreaks usually the output of colourScale, or a vector of breaks
style	Style for breaks, see Details
col	Colours to use, either a function or argument for brewer.pal
opacity	adds transparency to colours, either a single number, vector of length 2, or vector of same length as breaks
dec	Number of decimal places for the breaks
digits	Number of significant figures
firstBreak	If non-null, force the first break to take this value (often zero).
transform	A list of two functions to transform x and inverse transform the breaks, or a numeric value specifying a Box-Cox parameter.
revCol	Reverse the order of the colours.
exclude	A vector of values to change to NA when they appear in x
labels	Vector of names of levels, useful when style='unique'
multiples	break points must be multiples of these numbers times a power of 10
...	Additional arguments passed to classIntervals.

Details

colourScale produces intervals from x, each with a unique colour. Categories are determined with break points according to the following style options:

• quantile: quantile(x, prob=seq(0,1,len=breaks), )

equal: seq(min(x), max(x), len=breaks)

unique: sort(table(unique(x)))[1:breaks]

fixed: breaks

any other string: is passed to classIntervals

colorScale passes all it's arguments to colourScale

breaksForRates returns break points suitable for mapping incidence rates, which are positive and always include 1.0.

Value

A list with elements

plot	Vector of same length of x containing colours (RGB hex)
breaks	vector of break points
col	vector of unique colour values corresponding to breaks
colWithOpacity	as col, but with two digit transparency values appended.

See Also

legendBreaks,scaleBar, classIntervals

Examples

breaksForRates(13.6, breaks = 7) 

Npoints = 20

myPoints = vect(
	cbind(runif(Npoints), 51+runif(Npoints)), 
	atts=data.frame(
		y1=c(NA, rnorm(Npoints-1)), 
	    y2=c(sample(0:5, Npoints-1,replace=TRUE), NA)
	),
	crs=crsLL)



if(require('RColorBrewer', quietly=TRUE)) {
	theCol = 'RdYlBu'
} else {
	theCol = grDevices::heat.colors
}

myscale = colourScale(myPoints$y1, breaks=4, col=theCol,
 style="quantile", revCol=TRUE,dec=1)


data("netherlands")
nldElev = terra::unwrap(nldElev)
myscale = colourScale(nldElev, breaks=4, col=theCol, style='equal', dec=0)

oldpar = map.new(myPoints)
plot(myPoints, col=myscale$plot, pch=16,add=TRUE)
legendBreaks("topleft", myscale)


myscale2 = colourScale(myPoints$y1, breaks=8, col=rainbow, style="equal",
opacity=0.8, dec=2, revCol=TRUE)

map.new(myPoints)
plot(myPoints, col=myscale2$plot, pch=16,add=TRUE)
legendBreaks("topleft", myscale2)

if(require('RColorBrewer', quietly=TRUE)) {
	theCol = 'Set2'
} else {
	theCol = grDevices::heat.colors
}

myscale3 = colourScale(myPoints$y2,  breaks=3,col=theCol, style="unique",
	opacity=c(0.1, 0.9))

map.new(myPoints)
plot(myPoints, col=myscale3$plot, pch=16,add=TRUE)
legendBreaks("topleft", myscale3)

myPoints$y3 = exp(myPoints$y1)
myscale4 = colourScale(myPoints$y3,  breaks=4, style="equal",
	opacity=c(0.1, 0.9), transform=1.25,dec=0, firstBreak=0)

map.new(myPoints)
plot(myPoints, col=myscale4$plot, pch=16,add=TRUE)
legendBreaks("topleft", myscale4)


# raster with colour table

x = rast(extent=ext(0,15,0,10), res=1)
values(x) = sample(1:4, ncell(x), replace=TRUE)
myScale = colourScale(x, breaks=3, style='unique', col=c('red','blue','orange'))
if(utils::packageVersion("terra") >= "1.7-40" ) {
	terra::coltab(x) = myScale$colourtable
	plot(x)
} else {
	plot(x, breaks = myScale$breaks, col=myScale$col)
}
legendBreaks('topright', myScale)

par(oldpar)

mapmisc documentation built on April 15, 2024, 3 p.m.