\name{label}
\alias{label}
\alias{label<-}
\alias{label.default}
\alias{label.Surv}
\alias{label<-.default}
\alias{labelPlotmath}
\alias{labelLatex}
\alias{[.labelled}
\alias{print.labelled}
\alias{Label}
\alias{Label.data.frame}
\alias{llist}
\alias{prList}
\alias{putHcap}
\alias{putHfig}
\alias{plotmathTranslate}
\alias{as.data.frame.labelled}
\alias{data.frame.labelled}
\alias{reLabelled}
\alias{label.data.frame}
\alias{label<-.data.frame}
\alias{relevel.labelled}
\alias{combineLabels}
\title{
  Label Attribute of an Object
}
\description{
  \code{label(x)} retrieves the \code{label} attribute of \code{x}.
  \code{label(x) <- "a label"} stores the label attribute, and also puts
  the class \code{labelled} as the first class of \code{x} (for S-Plus
  this class is not used and methods for handling this class are
  not defined so the \code{"label"} and \code{"units"} attributes are lost
  upon subsetting).  The reason for having this class is so that the
  subscripting method for \code{labelled}, \code{[.labelled}, can preserve
  the \code{label} attribute in S.  Also, the \code{print}
  method for \code{labelled} objects prefaces the print with the object's
  \code{label} (and \code{units} if there).  If the variable is also given
  a \code{"units"} attribute using the \code{units} function, subsetting
  the variable (using \code{[.labelled}) will also retain the
  \code{"units"} attribute.

  \code{label} can optionally append a \code{"units"} attribute to the
  string, and it can optionally return a string or expression (for \R's
  \code{plotmath} facility) suitable for plotting.  \code{labelPlotmath}
  is a function that also has this function, when the input arguments are
  the \code{'label'} and \code{'units'} rather than a vector having those
  attributes.  When \code{plotmath} mode is used to construct labels, the
  \code{'label'} or \code{'units'} may contain math expressions but they
  are typed verbatim if they contain percent signs, blanks, or
  underscores.  \code{labelPlotmath} can optionally create the
  expression as a character string, which is useful in building
  \code{ggplot} commands.

	For \code{Surv} objects, \code{label} first looks to see if there is
	an overall \code{"label"} attribute for the object, then it looks for
	saved attributes that \code{Surv} put in the \code{"inputAttributes"}
	object, looking first at the \code{event} variable, then \code{time2},
	and finally \code{time}.  You can restrict the looking by specifying
	\code{type}.

	\code{labelLatex} constructs suitable LaTeX labels a variable or from the
	\code{label} and \code{units} arguments, optionally right-justifying
	\code{units} if \code{hfill=TRUE}.  This is useful when making tables
	when the variable in question is not a column heading.  If \code{x}
	is specified, \code{label} and \code{units} values are extracted from
	its attributes instead of from the other arguments.

  \code{Label} (actually \code{Label.data.frame}) is a function which generates
  S source code that makes the labels in all the variables in a data
  frame easy to edit.

  \code{llist} is like \code{list} except that it preserves the names or
  labels of the component variables in the variables \code{label}
  attribute.  This can be useful when looping over variables or using
  \code{sapply} or \code{lapply}. By using \code{llist} instead of
  \code{list} one can annotate the output with the current variable's name
  or label.  \code{llist} also defines a \code{names} attribute for the
  list and pulls the \code{names} from the arguments' expressions for
  non-named arguments.

	\code{prList} prints a list with element names (without the dollar
	sign as in default list printing) and if an element of the list is an
	unclassed list with a name, all of those elements are printed, with
	titles of the form "primary list name : inner list name".  This is
	especially useful for Rmarkdown html notebooks when a user-written
	function creates multiple html and graphical outputs to all be printed
	in a code chunk.  Optionally the names can be printed after the
	object, and the \code{htmlfig} option provides more capabilities when
	making html reports.  \code{prList} does not work for regular html
	documents. 

	\code{putHfig} is similar to \code{prList} but for a single graphical
	object that is rendered with a \code{print} method, making it easy to
	specify long captions, and short captions for the table of contents in
	HTML documents.
	Table of contents entries are generated with the short caption, which
	is taken as the long caption if there is none.  One can optionally not
	make a table of contents entry.  If argument \code{table=TRUE} table
	captions will be produced instead.  Using \code{expcoll},
	\code{markupSpecs} \code{html} function \code{expcoll} will be used to
	make tables expand upon clicking an arrow rather than always appear.

	\code{putHcap} is like \code{putHfig} except that it
	assumes that users render the graphics or table outside of the
	\code{putHcap} call.  This allows things to work in ordinary html
	documents.  \code{putHcap} does not handle collapsed text.

  \code{plotmathTranslate} is a simple function that translates certain
  character strings to character strings that can be used as part of \R
  \code{plotmath} expressions.  If the input string has a space or percent
  inside, the string is surrounded by a call to \code{plotmath}'s
  \code{paste} function.

  \code{as.data.frame.labelled} is a utility function that is called by
  \code{[.data.frame}.  It is just a copy of \code{as.data.frame.vector}.
  \code{data.frame.labelled} is another utility function, that adds a
  class \code{"labelled"} to every variable in a data frame that has a
  \code{"label"} attribute but not a \code{"labelled"} class.

  \code{relevel.labelled} is a method for preserving \code{label}s with the \code{relevel} function.

  \code{reLabelled} is used to add a \code{'labelled'} class back to
  variables in data frame that have a 'label' attribute but no 'labelled'
  class.  Useful for changing \code{cleanup.import()}'d S-Plus data
  frames back to general form for \R and old versions of S-Plus.
}
\usage{
label(x, default=NULL, ...)

\method{label}{default}(x, default=NULL, units=plot, plot=FALSE,
      grid=FALSE, html=FALSE, \dots)

\method{label}{Surv}(x, default=NULL, units=plot, plot=FALSE,
      grid=FALSE, html=FALSE, type=c('any', 'time', 'event'), \dots)

\method{label}{data.frame}(x, default=NULL, self=FALSE, \dots)

label(x, ...) <- value

\method{label}{default}(x, ...) <- value

\method{label}{data.frame}(x, self=TRUE, ...) <- value

labelPlotmath(label, units=NULL, plotmath=TRUE, html=FALSE, grid=FALSE,
              chexpr=FALSE)

labelLatex(x=NULL, label='', units='', size='smaller[2]',
           hfill=FALSE, bold=FALSE, default='', double=FALSE)

\method{print}{labelled}(x, \dots)   ## or x - calls print.labelled

Label(object, \dots)

\method{Label}{data.frame}(object, file='', append=FALSE, \dots)

llist(\dots, labels=TRUE)

prList(x, lcap=NULL, htmlfig=0, after=FALSE)

putHfig(x, \dots, scap=NULL, extra=NULL, subsub=TRUE, hr=TRUE,
        table=FALSE, file='', append=FALSE, expcoll=NULL)

putHcap(\dots, scap=NULL, extra=NULL, subsub=TRUE, hr=TRUE,
        table=FALSE, file='', append=FALSE)

plotmathTranslate(x)

data.frame.labelled(object)

\method{relevel}{labelled}(x, \dots)

reLabelled(object)

combineLabels(\dots)
}
\arguments{
  \item{x}{
    any object (for \code{plotmathTranslate} is a character string). For
		\code{relevel} is a \code{factor} variable.  For \code{prList} is a
		named list.  For \code{putHfig} is a graphical object for which a
		\code{print} method will render the graphic (e.g., a \code{ggplot2}
		or \code{plotly} object).
  }
  \item{self}{lgoical, where to interact with the object or its components}
  \item{units}{
    set to \code{TRUE} to append the \code{'units'} attribute (if present)
    to the returned label.  The \code{'units'} are surrounded
    by brackets.  For \code{labelPlotmath} and \code{labelLatex} is a
		character string containing the units of measurement.  When
		\code{plot} is \code{TRUE}, \code{units} defaults to \code{TRUE}.
  }
  \item{plot}{
    set to \code{TRUE} to return a label suitable for \R's \code{plotmath}
    facility (returns an expression instead of a character string) if R is
    in effect.  If \code{units} is also \code{TRUE}, and if both
    \code{'label'} and \code{'units'} attributes are present, the
    \code{'units'} will appear after the label but in smaller type and
    will not be surrounded by brackets.
  }
  \item{default}{
    if \code{x} does not have a \code{'label'} attribute and
    \code{default} (a character string) is specified, the label will be
    taken as \code{default}.  For \code{labelLatex} the \code{default}
		is the name of the first argument if it is a variable and not a label.
  }
  \item{grid}{
    Currently \R's \code{lattice} and \code{grid} functions do not support
    \code{plotmath} expressions for \code{xlab} and \code{ylab}
    arguments.  When using \code{lattice} functions in \R, set the
    argument \code{grid} to \code{TRUE} so that \code{labelPlotmath} can
    return an ordinary character string instead of an expression.
  }
	\item{html}{set to \code{TRUE} to use HTML formatting instead of
		plotmath expressions for constructing labels with units}
	\item{type}{for \code{Surv} objects specifies the type of element for
		which to restrict the search for a label}
  \item{label}{a character string containing a variable's label}
  \item{plotmath}{
    set to \code{TRUE} to have \code{labelMathplot} return an expression
    for plotting using \R's \code{plotmath} facility.  If \R is not in
    effect, an ordinary character string is returned.
  }
	\item{chexpr}{set to \code{TRUE} to have \code{labelPlotmath} return a
		character string of the form \code{"expression(...)"}}
	\item{size}{LaTeX size for \code{units}.  Default is two sizes smaller
		than \code{label}, which assumes that the LaTeX \code{relsize}
		package is in use.}
	\item{hfill}{set to \code{TRUE} to right-justify \code{units} in the
		field.  This is useful when multiple labels are being put into rows
		in a LaTeX \code{tabular} environment, and will cause a problem if
		the label is used in an environment where \code{hfill} is not
		appropriate.}
	\item{bold}{set to \code{TRUE} to have \code{labelLatex} put the
		\code{label} in bold face.}
	\item{double}{set to \code{TRUE} to represent backslash in LaTeX as
		four backslashes in place of two.  This is needed if, for example,
		you need to convert the result using \code{as.formula}}
  \item{value}{
    the label of the object, or "".
  }
  \item{object}{
    a data frame
  }
  \item{\dots}{
    a list of variables or expressions to be formed into a \code{list}.
    Ignored for \code{print.labelled}.  For \code{relevel} is the
		\code{level} (a single character string) to become the new reference
		(first) category.  For \code{putHfig} and \code{putHcap} represents
		one or more character strings that are pasted together, separated by
		a blank. 
  }
  \item{file}{
    the name of a file to which to write S source code.  Default is
    \code{""}, meaning standard output.  For \code{putHcap}, set
		\code{file} to \code{FALSE} to return a character vector instead of
		writing to \code{file}.}
  \item{append}{
    set to \code{TRUE} to append code generated by \code{Label} to file
		\code{file}.  Also used for \code{putHfig, putHcap}.
  }
  \item{labels}{
    set to \code{FALSE} to make \code{llist} ignore the variables'
		\code{label} attribute and  use the variables' names.
  }
	\item{lcap}{an optional vector of character strings corresponding to
		elements in \code{x} for \code{prList}.  These contain long captions
		that do not appear in the table of contents but which are printed
		right after the short caption in the body, in the same font.}
	\item{htmlfig}{for \code{prList} set to \code{1} to use HTML markup by
		running the object names through \code{markupSpecs$html$cap} for
			figure captions.  Set \code{htmlfig=2} to also preface the figure
			caption with \code{"### "} so that it will appear in the table of
			contents.}
	\item{after}{set to \code{TRUE} to have \code{prList} put names after
		the printed object instead of before}
	\item{scap}{a character string specifying the short (or possibly only)
		caption.}
	\item{extra}{an optional vector of character strings.  When present
		the long caption will be put in the first column of an HTML table
		and the elements of \code{extra} in subsequent columns.  This allows
		extra information to appear in the long caption in a way that is
		right-justified to the right of the flowing caption text.}
	\item{subsub}{set to \code{FALSE} to suppress \code{"### "} from being
		placed in front of the short caption.  Set it to different character
		string to use that instead.  Set it to \code{""} to ignore short
		captions entirely.  For example to use second-level headings for the
	table of contents specify \code{subsub="## "}.}
	\item{hr}{applies if a caption is present.  Specify \code{FALSE} to
		not put a horizontal line before the caption and figure.}
	\item{table}{set to \code{TRUE} to produce table captions instead of
		figure captions}
	\item{expcoll}{character string to be visible, with a clickable arrow
		following to allow initial hiding of a table and its captions.
		Cannot be used with \code{table=FALSE}.}
}
\value{
  \code{label} returns the label attribute of x, if any; otherwise, "".
  \code{label} is used
  most often for the individual variables in data frames.  The function
  \code{sas.get} copies labels over from SAS if they exist.
}
\seealso{
  \code{\link{sas.get}}, \code{\link{describe}},
	\code{\link{extractlabs}}, \code{\link{hlab}} 
}
\examples{
age <- c(21,65,43)
y   <- 1:3
label(age) <- "Age in Years"
plot(age, y, xlab=label(age))

data <- data.frame(age=age, y=y)
label(data)

label(data, self=TRUE) <- "A data frame"
label(data, self=TRUE)

x1 <- 1:10
x2 <- 10:1
label(x2) <- 'Label for x2'
units(x2) <- 'mmHg'
x2
x2[1:5]
dframe <- data.frame(x1, x2)
Label(dframe)

labelLatex(x2, hfill=TRUE, bold=TRUE)
labelLatex(label='Velocity', units='m/s')

##In these examples of llist, note that labels are printed after
##variable names, because of print.labelled
a <- 1:3
b <- 4:6
label(b) <- 'B Label'
llist(a,b)
llist(a,b,d=0)
llist(a,b,0)


w <- llist(a, b>5, d=101:103)
sapply(w, function(x){
  hist(as.numeric(x), xlab=label(x))
  # locator(1)   ## wait for mouse click
})

# Or: for(u in w) {hist(u); title(label(u))}
}
\keyword{attribute}
\keyword{misc}
\keyword{utilities}
% Converted by Sd2Rd version 1.21.