xNam {semEff}

Get Model Term Names

Description

Extract term names from a fitted model object.

Usage

xNam(mod, intercept = TRUE, aliased = TRUE, list = FALSE, env = NULL)

Arguments

mod

A fitted model object, or a list or nested list of such objects.

intercept

Logical, whether the intercept should be included.

aliased

Logical, whether names of aliased terms should be included (see Details).

list

Logical, whether names should be returned as a list, with all multi-coefficient terms grouped under their main term names.

env

Environment in which to look for model data (used to construct the model frame). Defaults to the formula() environment.

Details

Extract term names from a fitted model. Names of terms for which coefficients cannot be estimated are also included if aliased = TRUE (default). These may be terms which are perfectly correlated with other terms in the model, so that the model design matrix is rank deficient.

Value

A character vector or list/nested list of term names.

Examples

# Term names from Shipley SEM
m <- shipley.sem
xNam(m)
xNam(m, intercept = FALSE)

# Model with different types of predictor (some multi-coefficient terms)
d <- data.frame(
  y = rnorm(100),
  x1 = rnorm(100),
  x2 = as.factor(rep(c("a", "b", "c", "d"), each = 25)),
  x3 = rep(1, 100)
)
m <- lm(y ~ poly(x1, 2) + x2 + x3, data = d)
xNam(m)
xNam(m, aliased = FALSE)  # drop term that cannot be estimated (x3)
xNam(m, aliased = FALSE, list = TRUE)  # names as list