flat_expr: Flatten Expressions for Non-standard Evaluation

In mmrm: Mixed Models for Repeated Measures

Flatten Expressions for Non-standard Evaluation

Description

Used primarily to support the parsing of covariance structure definitions from formulas, these functions flatten the syntax tree into a hierarchy-less grammar, allowing for parsing that doesn't abide by R's native operator precedence.

Usage

flatten_call(call)

flatten_expr(expr)

Arguments

call, expr

(language) a language object to flatten.

Details

Where 1 + 2 | 3 in R's syntax tree is (|, (+, 1, 2), 3), flattening it into its visual order produces (1, +, 2, |, 3), which makes for more fluent interpretation of non-standard grammar rules used in formulas.

Value

A list of atomic values, symbols, infix operator names and subexpressions.

Functions

• flatten_call(): Flatten a call into a list of names and argument expressions.

  The call name and all arguments are flattened into the same list, meaning a call of the form sp_exp(a, b, c | d / e) produces a list of the form (sp_exp, a, b, c, |, d, /, e).

  flatten_call(quote(sp_exp(a, b, c | d / e)))
  

• flatten_expr(): Flatten nested expressions

  flatten_expr(quote(1 + 2 + 3 | 4))
  

mmrm documentation built on Oct. 7, 2024, 1:14 a.m.