expression.simplify: Recursively Simplify an Expression in a given Environment

In thomasWeise/functionComposeR: R Package for Composing and Canonicalizing Functions

Description

We try to recursivelys simplify the expression expr by trying to evaluate all of its sub-expressions. A sub-expression that has been successfully evaluated is replaced with the evaluation result.

expression.simplify is somewhat similar to eval, with the difference that it can deal with expressions which are only partially evaluatable. The body of the function function(x) { 5+4+x }, for instance, cannot be fully evaluated if the value of x is unknown. We can, however, replace the 5+4 with a 9.

Since this function is still an early draft, there may be many scenarios where it does not simplify an expression as much as it could be possible. Hopefully, we can impove this in the future and make it more powerful.

Additionally, this function makes sure that identical sub-expressions will be replaced by the exactly same object. This may have advantages, e.g., making the expression more cache friendly when the object is a vector.

Usage

expression.simplify(expr, envir)

Arguments

expr	the expression to be simplified
envir	the environment in which the expression is to be simplified

Examples

expression.simplify(5+3)
# [1] 8
k <- 8
expression.simplify( ((5+3*k)-1)/k - 2^tan(k) )
# [1] 3.491024
f <- function(x) { 5+3+x }
expression.simplify(body(f), envir=environment(f))
# 8 + x

thomasWeise/functionComposeR documentation built on May 28, 2019, 4:03 p.m.