Group or cluster covariates

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

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.

See also

f()

Author

Havard Rue hrue@r-inla.org

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))