Returns all lowest to highest order interaction terms from a model.

Usage

find_interactions(
x,
component = c("all", "conditional", "zi", "zero_inflated", "dispersion", "instruments"),
flatten = FALSE
)

Arguments

x

A fitted model.

component

Should all predictor variables, predictor variables for the conditional model, the zero-inflated part of the model, the dispersion term or the instrumental variables be returned? Applies to models with zero-inflated and/or dispersion formula, or to models with instrumental variable (so called fixed-effects regressions). May be abbreviated. Note that the conditional component is also called count or mean component, depending on the model.

flatten

Logical, if TRUE, the values are returned as character vector, not as list. Duplicated values are removed.

Value

A list of character vectors that represent the interaction terms. Depending on component, the returned list has following elements (or NULL, if model has no interaction term):

• conditional, interaction terms that belong to the "fixed effects" terms from the model

• zero_inflated, interaction terms that belong to the "fixed effects" terms from the zero-inflation component of the model

• instruments, for fixed-effects regressions like ivreg, felm or plm, interaction terms that belong to the instrumental variables

Examples

data(mtcars)

m <- lm(mpg ~ wt + cyl + vs, data = mtcars)
find_interactions(m)
#> NULL

m <- lm(mpg ~ wt * cyl + vs * hp * gear + carb, data = mtcars)
find_interactions(m)
#> \$conditional
#> [1] "wt:cyl"     "vs:hp"      "vs:gear"    "hp:gear"    "vs:hp:gear"
#>