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Extract basic variable names from expression

Source: R/used.R
bru_used_vars.Rd

Extracts the variable names from an R expression by pre- and post-processing around all.vars(). First replaces $ with [[ indexing, so that internal column/variable names are ignored, then calls all.vars().

Usage

bru_used_vars(x, functions = FALSE)

# S3 method for class 'character'
bru_used_vars(x, functions = FALSE)

# S3 method for class 'expression'
bru_used_vars(x, functions = FALSE)

# S3 method for class 'formula'
bru_used_vars(x, functions = FALSE)

Arguments

x

A formula, expression, or character

functions

logical; if TRUE, include function names

Value

If successful, a character vector, otherwise NULL

Methods (by class)

  • bru_used_vars(formula): Only the right-hand side is used.

See also

Other bru_used: bru_used(), bru_used_update()

Examples

bru_used_vars(~.)
#> NULL
bru_used_vars(~ a + b + c_latent + d_eval())
#> [1] "a"        "b"        "c_latent"
bru_used_vars(expression(a + b + c_latent + d_eval()))
#> [1] "a"        "b"        "c_latent"

bru_used_vars(~., functions = TRUE)
#> NULL
bru_used_vars(~ a + b + c_latent + d_eval(), functions = TRUE)
#> [1] "+"        "a"        "b"        "c_latent" "d_eval"  
bru_used_vars(expression(a + b + c_latent + d_eval()), functions = TRUE)
#> [1] "expression" "+"          "a"          "b"          "c_latent"  
#> [6] "d_eval"    

bru_used_vars(a ~ b)
#> [1] "b"
bru_used_vars(expression(a ~ b))
#> [1] "a" "b"