as_label() transforms R objects into a short, human-readable description. You can use labels to:

  • Display an object in a concise way, for example to labellise axes in a graphical plot.

  • Give default names to columns in a data frame. In this case, labelling is the first step before name repair.

See also as_name() for transforming symbols back to a string. Unlike as_label(), as_string() is a well defined operation that guarantees the roundtrip symbol -> string -> symbol.

In general, if you don't know for sure what kind of object you're dealing with (a call, a symbol, an unquoted constant), use as_label() and make no assumption about the resulting string. If you know you have a symbol and need the name of the object it refers to, use as_string(). For instance, use as_label() with objects captured with enquo() and as_string() with symbols captured with ensym().

as_label(x)

Arguments

x

An object.

Transformation to string

  • Quosures are squashed before being labelled.

  • Symbols are transformed to string with as_string().

  • Calls are abbreviated.

  • Numbers are represented as such.

  • Other constants are represented by their type, such as <dbl> or <data.frame>.

Note that simple symbols should generally be transformed to strings with as_name(). Labelling is not a well defined operation and no assumption should be made about how the label is created. On the other hand, as_name() only works with symbols and is a well defined, deterministic operation.

See also

as_name() for transforming symbols back to a string deterministically.

Examples

# as_label() is useful with quoted expressions: as_label(expr(foo(bar)))
#> [1] "foo(bar)"
as_label(expr(foobar))
#> [1] "foobar"
# It works with any R object. This is also useful for quoted # arguments because the user might unquote constant objects: as_label(1:3)
#> [1] "<int>"
as_label(base::list)
#> [1] "<fn>"