formula.tools

** Programatic Utilities for Formulas, Expressions, Calls, Assignments and Other R Objects**

These utilities facilitate the programmatic manipulations of formulas, expressions, calls, names, symbols and other R language objects. These objects all share the same structure: a left-hand side (lhs), an operator (op) and right-hand side (rhs). This packages provides methods for accessing and modifying this structures as well as extracting and replacing names and symbols from these objects.

It is easiest to understand through the [#Examples].

Installation

Stable Version

install.packages('formula.tools')

Development Verison

devtools::install_github("decisionpatterns/formula.tools")

Important Functions

• lhs: get/set the left-hand side of an object
• rhs: get/set the right-hand side of an object
• op: get/set the operator of an object
• get.vars: like base::all.vars except all symbols, etc. can be interpolated on data, so that things like y ~ . can return the correct values.
• lhs.vars: get.vars on lhs of the object
• rhs.vars: get.vars on rhs of the object
• terms: get the terms from an object enterpolating on the data

Examples

Formula terms and operators can be accessed or changed.

form <- y ~ x 
lhs(form)  # y
lhs(form)
lhs(form) <- quote(t)