Generic group-with-known-covariance random effect (brms-style)

A user-friendly wrapper for any random effect whose covariance is a user-supplied matrix. Mirrors brms's (1 | gr(species, cov = M)). Inside a gllvmTMB() formula, this desugars to propto(0 + group | trait). The actual covariance matrix used by the engine is whatever is passed to the top-level phylo_vcv = argument of gllvmTMB(); the optional cov = argument inside the formula is retained for backward compatibility and as a hint to the reader, but is not used by the engine. Same convention as phylo() and phylo_rr().

Usage

gr(group, cov = NULL)

Arguments

group

An unquoted column name giving the grouping factor.

cov

Optional, ignored by the engine. The matrix actually used is whatever is passed to the phylo_vcv argument of gllvmTMB().

Value

A formula marker; never evaluated.

Examples

if (FALSE) { # \dontrun{
# Recommended:
fit <- gllvmTMB(value ~ 0 + trait + gr(species),
                data      = df,
                trait     = "trait",
                unit      = "species",
                cluster   = "species",
                phylo_vcv = Cphy)
# Also valid (cov = Cphy ignored by engine):
fit <- gllvmTMB(value ~ 0 + trait + gr(species, cov = Cphy),
                data      = df,
                trait     = "trait",
                unit      = "species",
                cluster   = "species",
                phylo_vcv = Cphy)
} # }