Coerce to factor

Checks whether a vector can be coerced to a factor without losing information, returning it silently if so. Otherwise an informative error message is signaled. to_factor is a synonym of to_fct().

Usage

to_fct(
  x,
  ...,
  levels = NULL,
  to_na = character(),
  x_arg = caller_arg(x),
  call = caller_env(),
  x_class = object_type(x)
)

to_factor(
  x,
  ...,
  levels = NULL,
  to_na = character(),
  x_arg = caller_arg(x),
  call = caller_env(),
  x_class = object_type(x)
)

# S3 method for class '`NULL`'
to_fct(x, ..., allow_null = TRUE, x_arg = caller_arg(x), call = caller_env())

Arguments

x

The object to stabilize.

...

Arguments passed to methods.

levels

(character) Expected levels. If NULL (default), the levels will be computed by base::factor().

to_na

(character) Values to convert to NA.

x_arg

(character(1)) The name of the object being stabilized to use in error messages. The automatic value will work in most cases, or pass it through from higher-level functions to make error messages clearer in unexported functions.

call

(environment) The execution environment to mention as the source of error messages.

x_class

(character(1)) The class name of the object being stabilized to use in error messages. Use this if you remove a special class from the object before checking its coercion, but want the error message to match the original class.

allow_null

(logical(1)) Is NULL an acceptable value?

Value

The input as a factor.

Details

This function has important differences from base::as.factor() and base::factor():

• Values are never silently coerced to NA unless they are explicitly supplied in the to_na argument.

• NULL values can be rejected as part of the call to this function (with allow_null = FALSE).

See also

Other factor functions: are_fct_ish(), specify_fct(), stabilize_fct(), stabilize_fct_scalar(), to(), to_fct_scalar()

Other stabilization functions: assert_present(), stabilize_any_of(), stabilize_arg(), stabilize_chr(), stabilize_chr_scalar(), stabilize_date(), stabilize_date_scalar(), stabilize_dbl(), stabilize_dbl_scalar(), stabilize_df(), stabilize_dttm(), stabilize_dttm_scalar(), stabilize_dur(), stabilize_dur_scalar(), stabilize_fct(), stabilize_fct_scalar(), stabilize_int(), stabilize_int_scalar(), stabilize_lgl(), stabilize_lgl_scalar(), stabilize_lst(), stabilize_time(), stabilize_time_scalar(), to_chr(), to_chr_scalar(), to_date(), to_date_scalar(), to_dbl(), to_dbl_scalar(), to_dttm(), to_dttm_scalar(), to_dur(), to_dur_scalar(), to_fct_scalar(), to_int(), to_int_scalar(), to_lgl(), to_lgl_scalar(), to_time(), to_time_scalar()

Examples

to_fct("a")
#> [1] a
#> Levels: a
to_fct(1:10)
#>  [1] 1  2  3  4  5  6  7  8  9  10
#> Levels: 1 2 3 4 5 6 7 8 9 10
to_fct(NULL)
#> NULL
try(to_fct(letters[1:5], levels = c("a", "c"), to_na = "b"))
#> Error in eval(expr, envir) : 
#>   Each value of `letters[1:5]` must be in the expected levels.
#> ℹ Allowed levels: "a" and "c".
#> ℹ Values that are converted to `NA`: "b".
#> ✖ Unexpected values: "d" and "e".