as_labeller.Rd

% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/labeller.r
\name{as_labeller}
\alias{as_labeller}
\title{Coerce to labeller function}
\usage{
as_labeller(x, default = label_value, multi_line = TRUE)
}
\arguments{
\item{x}{Object to coerce to a labeller function. If a named
character vector, it is used as a lookup table before being
passed on to \code{default}. If a non-labeller function, it is
assumed it takes and returns character vectors and is applied to
the labels. If a labeller, it is simply applied to the labels.}

\item{default}{Default labeller to process the labels produced by
lookup tables or modified by non-labeller functions.}

\item{multi_line}{Whether to display the labels of multiple factors
on separate lines. This is passed to the labeller function.}
}
\description{
This transforms objects to labeller functions. Used internally by
\code{\link[=labeller]{labeller()}}.
}
\examples{
p <- ggplot(mtcars, aes(disp, drat)) + geom_point()
p + facet_wrap(~am)

# Rename labels on the fly with a lookup character vector
to_string <- as_labeller(c(`0` = "Zero", `1` = "One"))
p + facet_wrap(~am, labeller = to_string)

# Quickly transform a function operating on character vectors to a
# labeller function:
appender <- function(string, suffix = "-foo") paste0(string, suffix)
p + facet_wrap(~am, labeller = as_labeller(appender))

# If you have more than one faceting variable, be sure to dispatch
# your labeller to the right variable with labeller()
p + facet_grid(cyl ~ am, labeller = labeller(am = to_string))
}
\seealso{
\code{\link[=labeller]{labeller()}}, \link{labellers}
}
\keyword{internal}