split_terms: Split object into terms

In formula.tools: Programmatic Utilities for Manipulating Formulas, Expressions, Calls, Assignments and Other R Objects

Description

Split formulas, call and expressions into terms.

Usage

split_terms(x, recursive = FALSE)

Arguments

x	object to split terms from
recursive	logical; whether to split terms recursively in parenthetical enclosed terms (depth-first). (Default: FALSE)

Details

Unlike the [terms()] function, 'split_terms' does not use [stats::terms()] and instead just splits 'x' into an **expression vector** of terms. (Terms are the mathematical notion of terms). The signs of the terms are preserved.

If 'recursive' is 'TRUE', splitting occurs recursively, i.e. parsing of the input descends into parenthetical expressions '(...)'.

See **examples**.

Value

experession vector of terms

References

* [SO: How to split a formula](https://stackoverflow.com/questions/39155701/how-to-split-a-formula-in-r)

See Also

* [terms()]

Examples

  
  split_terms(1)                   # 1
  split_terms( quote(a) )          # a     
  split_terms( quote(-a) )         # -a   
  split_terms( quote(a+1) )        # a, 1
  split_terms( quote(1+a) )        # 1, a
  split_terms( quote(-1+a) )       # -1, a
  split_terms( quote(-1-a) )
  
  split_terms( quote(a+b+c) )      # a,b,c
  split_terms( quote((a+b)+1) )    # (a+b),1
  split_terms( quote((a+b)+1), recursive=TRUE )    # a,b,1
  split_terms( quote((a-b)+1), recursive=TRUE )    # a,-b,1
  split_terms( quote(-a) )         # -a
  
  split_terms( quote(a-1) )        # a, -1
  split_terms( quote(-a-1))        # -a, -1
  split_terms( quote( -(a+1) ) )   # -(a+1)
  split_terms( quote( -(a+1) ), recursive=TRUE )  # -a,-1
  
  split_terms( quote( ---a ))
  split_terms( quote( -(a+(b-(c+d)))), recursive=TRUE )
  

formula.tools documentation built on May 2, 2019, 1:45 p.m.