ncut {Epi}R Documentation

Function to group a variable in intervals.

Description

Cuts a continuous variable in intervals. As opposed to cut which returns a factor, ncut returns a numeric variable.

Usage

ncut(x, breaks, type="left" )

Arguments

x A numerical vector.
breaks Vector of breakpoints. NA will results for values below min(x) if type="left", for values above max(x) if type="right" and for values outside range(x) if type="mid"
type Character: one of c("left","right","mid"), indicating whether the left, right or midpoint of the intervals defined in breaks is returned.

Details

The function uses the base function findInterval.

Value

A numerical vector of the same length as x.

Author(s)

Bendix Carstensen, Steno Diabetes Center, bxc@steno.dk, http://www.biostat.ku.dk/~bxc/, with essential input from Martyn Plummer, IARC.

See Also

cut, findInterval

Examples

br <- c(-2,0,1,2.5)
x <- c( rnorm( 10 ), br, -3, 3 )
cbind( x, l=ncut( x, breaks=br, type="l" ),
          m=ncut( x, breaks=br, type="m" ),
          r=ncut( x, breaks=br, type="r" ) )[order(x),]
x <- rnorm( 200 )
plot( x, ncut( x, breaks=br, type="l" ), pch=16, col="blue", ylim=range(x) )
abline( 0, 1 )
abline( v=br )
points( x, ncut( x, breaks=br, type="r" ), pch=16, col="red" )
points( x, ncut( x, breaks=br, type="m" ), pch=16, col="green" )

[Package Epi version 1.0.12 Index]