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Small helper functions

Source: R/utilities.R
trim_ws.Rd

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. 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 data.frame
trim_ws(x, character_only = TRUE, ...)

n_unique(x, ...)

# S3 method for default
n_unique(x, na.rm = TRUE, ...)

safe_deparse(x, ...)

safe_deparse_symbol(x)

has_single_value(x, na.rm = 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.

na.rm

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\")"