ERROR
s are thrown when a match is not made and where the match is
ambiguous. However, sometimes ambiguities are inevitable. Consider the case
where choices = c("ab", "abc")
, then there's no way to choose "ab"
because "ab"
is a prefix for "ab"
and "abc"
. If this is the case, you
need to provide a full match, i.e. using arg = "ab"
will get you "ab"
without an error, however arg = "a"
will throw an ambiguity error.
When choices
is NULL
, the choices
are obtained from a default setting
for the formal argument arg
of the function from which str_match_arg
was
called. This is consistent with base::match.arg()
. See the examples for
details.
When arg
and choices
are identical and several_ok = FALSE
, the first
element of choices
is returned. This is consistent with
base::match.arg()
.
This function inspired by RSAGA::match.arg.ext()
. Its behaviour is almost
identical (the difference is that RSAGA::match.arg.ext(..., ignore.case = TRUE)
always returns in all lower case; strex::match_arg(..., ignore_case = TRUE)
ignores case while matching but returns the element of choices
in
its original case). RSAGA
is a heavy package to depend upon so
strex::match_arg()
is handy for package developers.
This function is designed to be used inside of other functions. It's fine to
use it for other purposes, but the error messages might be a bit weird.