inla.group {INLA} | R Documentation

## Group or cluster covariates

### Description

`inla.group` group or cluster covariates so to reduce the number of unique values

### Usage

    inla.group(x, n = 25, method = c("cut", "quantile"), idx.only = FALSE)

### Arguments

`x` | The vector of covariates to group.
`n` | Number of classes or bins to group into.
`method` | Group either using bins with equal length intervals (`method = "cut"`), or equal distance in the ‘probability’ scale using the quantiles (`method = "quantile"`).
`idx.only` | Option to return the index only and not the `method`.

### Value

`inla.group` return the new grouped covariates where the classes are set to the median of all the covariates belonging to that group.

### Author(s)

Havard Rue hrue@r-inla.org

### See Also

`f`

### Examples

    ## this gives groups 3 and 8
    x = 1:10
    x.group = inla.group(x, n = 2)

    ## this is the intended use, to reduce the number of unique values in
    ## the of first argument of f()
    n = 100
    x = rnorm(n)
    y = x + rnorm(n)
    result = inla(y ~ f(inla.group(x, n = 20), model = "iid"), data=data.frame(y=y,x=x))

[Package INLA version 18.07.12 Index]