Factor type

fct(a, b, ...) accepts a factor with exactly those levels, and promotes character input whose values are all among them. fct() with no arguments accepts any factor and never coerces.

Usage

fct(...)

Arguments

...

The levels, in order.

Value

A type.

Details

Use one_of() when you want a plain string out, and fct() when you want a factor with a fixed, ordered level set.

See also

one_of(), primitives

Examples

size <- fct("low", "mid", "high")
size("mid")
#> [1] mid
#> Levels: low mid high
levels(size(c("high", "low")))
#> [1] "low"  "mid"  "high"
try(size("enormous"))
#> Error : 1 validation problem in fct("low", "mid", "high")
#>   <value>  expected fct("low", "mid", "high"), got chr[1] "enormous"  -- levels are low, mid, high

fct()(factor("anything"))
#> [1] anything
#> Levels: anything
schema(size)
#> $type
#> [1] "array"
#> 
#> $items
#> $items$type
#> [1] "string"
#> 
#> $items$enum
#> $items$enum[[1]]
#> [1] "low"
#> 
#> $items$enum[[2]]
#> [1] "mid"
#> 
#> $items$enum[[3]]
#> [1] "high"
#> 
#> 
#>