Value Predicates for Common Object Types

is.boolean checks if an object is a single logical value (TRUE or FALSE).

is.string checks if an object is a single (non-NA) character string.

nzstring checks if an object is a single (non-NA) non-empty character string.

Usage

is.boolean(x)

is.string(x)

nzstring(x)

Arguments

x

an object to be tested.

Value

TRUE or FALSE.

Details

The string helpers differ slightly from what you may expect from base R as NA_character_ is not considered a string. For example:

nzchar(NA_character_)
#> [1] TRUE
is.string(NA_character_)
#> [1] FALSE
nzstring(NA_character_)
#> [1] FALSE

Examples

is.boolean(TRUE)
#> [1] TRUE
is.boolean(NA)
#> [1] FALSE

is.string("hello")
#> [1] TRUE
is.string(NA_character_)
#> [1] FALSE
is.string("")
#> [1] TRUE

nzstring("")
#> [1] FALSE