colourScale {mapmisc}

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)