Small helper functions — trim

Collection of small helper functions. trim_ws() is an efficient function to trim leading and trailing whitespaces from character vectors or strings. n_unique() returns the number of unique values in a vector. has_single_value() is equivalent to n_unique() == 1 but is faster (note the different default for the remove_na argument). safe_deparse() is comparable to deparse1(), i.e. it can safely deparse very long expressions into a single string. safe_deparse_symbol() only deparses a substituted expressions when possible, which can be much faster than deparse(substitute()) for those cases where substitute() returns no valid object name.

Usage

trim_ws(x, ...)

# S3 method for class 'data.frame'
trim_ws(x, character_only = TRUE, ...)

n_unique(x, ...)

# Default S3 method
n_unique(x, remove_na = TRUE, ...)

safe_deparse(x, ...)

safe_deparse_symbol(x)

has_single_value(x, remove_na = FALSE, ...)

Arguments

x: A (character) vector, or for some functions may also be a data frame.
...: Currently not used.
character_only: Logical, if TRUE and x is a data frame or list, only processes character vectors.
remove_na: Logical, if missing values should be removed from the input.

Value

n_unique(): For a vector, n_unique always returns an integer value, even if the input is NULL (the return value will be 0 then). For data frames or lists, n_unique() returns a named numeric vector, with the number of unique values for each element.
has_single_value(): TRUE if x has only one unique value, FALSE otherwise.
trim_ws(): A character vector, where trailing and leading white spaces are removed.
safe_deparse(): A character string of the unevaluated expression or symbol.
safe_deparse_symbol(): A character string of the unevaluated expression or symbol, if x was a symbol. If x is no symbol (i.e. if is.name(x) would return FALSE), NULL is returned.

Examples

trim_ws("  no space!  ")
#> [1] "no space!"
n_unique(iris$Species)
#> [1] 3
has_single_value(c(1, 1, 2))
#> [1] FALSE

# safe_deparse_symbol() compared to deparse(substitute())
safe_deparse_symbol(as.name("test"))
#> [1] "test"
deparse(substitute(as.name("test")))
#> [1] "as.name(\"test\")"