Check Named Argument

Checks whether an argument has valid (non-NULL, non-empty, and non-NA) names.

Usage

arg_named(x, .arg = rlang::caller_arg(x), .msg = NULL, .call)

arg_colnamed(x, .arg = rlang::caller_arg(x), .msg = NULL, .call)

Arguments

x

the argument to be checked

.arg

the name of the argument supplied to x to appear in error messages. The default is to extract the argument's name using rlang::caller_arg(). Ignored if .msg is supplied.

.msg

an optional alternative message to display if an error is thrown instead of the default message.

.call

the execution environment of a currently running function, e.g. .call = rlang::current_env(). The corresponding function call is retrieved and mentioned in error messages as the source of the error. Passed to err(). Set to NULL to omit call information. The default is to search along the call stack for the first user-facing function in another package, if any.

Value

Returns NULL invisibly if an error is not thrown.

Details

arg_named() works for vectors, lists, and data frames. To check whether a matrix has column names, use arg_colnamed() (which also works for data frames, but not vectors or lists).

See also

rlang::is_named(), names(), colnames(), arg_data()

Examples

obj <- c(1,
         B = 2,
         C = 3)

try(arg_named(obj)) # Error: one name is blank
#> Error : `obj` must have non-empty and non-NA names.

names(obj)[1L] <- "A"
try(arg_named(obj)) # No error

obj2 <- unname(obj)
try(arg_named(obj2)) # Error: no names
#> Error : `obj2` must have non-empty and non-NA names.

# Matrix and data frame
mat <- matrix(1:6, ncol = 2L)
colnames(mat) <- c("A", "B")

try(arg_named(mat))    # Error: matrices are not named
#> Error : `mat` must have non-empty and non-NA names.
try(arg_colnamed(mat)) # No error

dat <- as.data.frame(mat)
try(arg_named(dat))    # No error: data frames are named
try(arg_colnamed(dat)) # No error

colnames(mat) <- NULL
try(arg_colnamed(mat)) # Error: no colnames
#> Error : `mat` must have non-empty and non-NA names.