ncut: Function to group a variable in intervals. In Epi: A Package for Statistical Analysis in Epidemiology

Description

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

Usage

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

Arguments

 `x` A numerical vector. `breaks` Vector of breakpoints. `NA` will results for values below `min(breaks)` if `type="left"`, for values above `max(breaks)` if `type="right"` and for values outside `range(breaks)` 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, [email protected], http://BendixCarstensen.com, with essential input from Martyn Plummer, IARC.

`cut`, `findInterval`
 ``` 1 2 3 4 5 6 7 8 9 10 11``` ```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" ) ```