Formula Interface - Common Arguments

Common formula-based interface shared by multiple functions.

Arguments

formula: a formula of the form lhs ~ rhs, where lhs gives the response values and rhs the corresponding groups or explanatory variables.
data: an optional matrix or data frame (or similar; see model.frame()) containing the variables in the formula. By default the variables are taken from environment(formula).
subset: an optional vector specifying a subset of observations to be used in the analysis.
na.action: a function which indicates what should happen when the data contain NAs. Defaults to getOption("na.action").

Details

Formula interfaces are evaluated using model.frame(), following standard R conventions. The left-hand side of the formula must contain the response variable. The right-hand side typically specifies a grouping or explanatory variable. Only formulas with a single response and at least one explanatory variable are supported.