classBreaks {spatialEco}

Class breaks

Description

Finds class breaks in a distribution

Usage

classBreaks(x, n, type = c("equal", "quantile", "std", "geometric"))

Arguments

x

A vector to find breaks for

n

Number of breaks

type

Statistic used to find breaks c("equal", "quantile", "std", "geometric")

Details

The robust std method uses sqrt(sum(x^2)/(n-1)) to center the data before deriving "pretty" breaks.

Value

A vector containing class break values the length is n+1 to allow for specification of ranges

Author(s)

Jeffrey S. Evans <[e-mail]>

Examples

 y <- rnbinom(100, 10, 0.5)
   classBreaks(y, 10)  
   classBreaks(y, 10, type="quantile")
 
opar <- par(no.readonly=TRUE)
   par(mfrow=c(2,2))
     d <- density(y)
     plot(d, type="n", main="Equal Area breaks")
       polygon(d, col="cyan")
       abline(v=classBreaks(y, 10)) 
     plot(d, type="n", main="Quantile breaks")
       polygon(d, col="cyan")
       abline(v=classBreaks(y, 10, type="quantile"))
     plot(d, type="n", main="Robust Standard Deviation breaks")
       polygon(d, col="cyan")
       abline(v=classBreaks(y, 10, type="std"))
     plot(d, type="n", main="Geometric interval breaks")
       polygon(d, col="cyan")
       abline(v=classBreaks(y, 10, type="geometric"))
 par(opar)
	
 ( y.breaks <- classBreaks(y, 10) )   	
 cut(y, y.breaks, include.lowest = TRUE, labels = 1:10)