parse_formula: Parse casting formulae.

In reshape2: Flexibly Reshape Data: A Reboot of the Reshape Package

Description

There are a two ways to specify a casting formula: either as a string, or a list of quoted variables. This function converts the former to the latter.

Usage

parse_formula(formula = "...  ~ variable", varnames, value.var = "value")

Arguments

formula	formula to parse
varnames	names of all variables in data
value.var	name of variable containing values

Details

Casting formulas separate dimensions with ~ and variables within a dimension with + or *. . can be used as a placeholder, and ... represents all other variables not otherwise used.

Examples

reshape2:::parse_formula("a + ...", letters[1:6])
reshape2:::parse_formula("a ~ b + d")
reshape2:::parse_formula("a + b ~ c ~ .")

Example output

[[1]]
List of 6
 $ a: symbol a
 $ b: symbol b
 $ c: symbol c
 $ d: symbol d
 $ e: symbol e
 $ f: symbol f
 - attr(*, "env")=<environment: 0x27e4ce0> 
 - attr(*, "class")= chr "quoted"

[[1]]
List of 1
 $ a: symbol a
 - attr(*, "env")=<environment: 0x18a9608> 
 - attr(*, "class")= chr "quoted"

[[2]]
List of 2
 $ b: symbol b
 $ d: symbol d
 - attr(*, "env")=<environment: 0x18a9608> 
 - attr(*, "class")= chr "quoted"

[[1]]
List of 2
 $ a: symbol a
 $ b: symbol b
 - attr(*, "env")=<environment: 0x31efe88> 
 - attr(*, "class")= chr "quoted"

[[2]]
List of 1
 $ c: symbol c
 - attr(*, "env")=<environment: 0x31efe88> 
 - attr(*, "class")= chr "quoted"

[[3]]
 list()
 - attr(*, "env")=<environment: 0x31efe88> 
 - attr(*, "class")= chr "quoted"

reshape2 documentation built on April 14, 2020, 5:26 p.m.