formula.utils: Utilities for working with formulas

In EconModels/MacroGrowth: Economics Models

Description

Some functions to make it easier to build and minipulate formulas

Usage

build_formula(lhs, rhs, env = parent.frame(), op = "+")

keep_summands(formula, n, right = TRUE, env = environment(formula),
  op = "+")

summands(formula, n, right = TRUE, op = "+")

replace_summand(formula, n, term, right = TRUE, op = "+",
  env = environment(formula))

Arguments

lhs, rhs	list or vector of character strings containing summands for left and right hand sides of a formula. NULLs are ignored.
env	an environment to attach to the formula
op	The operator to use for splitting into terms.
formula	a formula
n	a vector of integer indices. Negatives can be used to deselect.
right	a logical indicating whether to operate on the right side (else the left) of the formula.
term	a character string containing a new term

Examples

a <- build_formula(c("a", "b"), c("x", "y", "log(x*y)")); a
b <- build_formula("response", list("x", "y", NULL, "log(x)"), op="*"); b
f <- build_formula( "iGDP", list("iK", "iL", "iQp", "iYear")); f
g <- build_formula( "iGDP", c("iK", "iL", "iQp", "iYear")); g
identical(f,g)
summands(a)
summands(a, right=FALSE)
summands(b, op="*")
keep_summands(f, 3)
keep_summands(f, -3)
keep_summands(f, 2:4)
h <- replace_summand( f, 3, paste(summands(f, 3), lhs(f), sep="/")); h

EconModels/MacroGrowth documentation built on Dec. 17, 2019, 10:41 p.m.