label(x) retrieves the label attribute of x.
  label(x) <- "a label" stores the label attribute, and also puts
  the class labelled as the first class of x (for S-Plus
  this class is not used and methods for handling this class are
  not defined so the "label" and "units" attributes are lost
  upon subsetting).  The reason for having this class is so that the
  subscripting method for labelled, [.labelled, can preserve
  the label attribute in S.  Also, the print
  method for labelled objects prefaces the print with the object's
  label (and units if there).  If the variable is also given
  a "units" attribute using the units function, subsetting
  the variable (using [.labelled) will also retain the
  "units" attribute.
label can optionally append a "units" attribute to the
  string, and it can optionally return a string or expression (for R's
  plotmath facility) suitable for plotting.  labelPlotmath
  is a function that also has this function, when the input arguments are
  the 'label' and 'units' rather than a vector having those
  attributes.  When plotmath mode is used to construct labels, the
  'label' or 'units' may contain math expressions but they
  are typed verbatim if they contain percent signs, blanks, or
  underscores.  labelPlotmath can optionally create the
  expression as a character string, which is useful in building
  ggplot commands.
For Surv objects, label first looks to see if there is
	an overall "label" attribute for the object, then it looks for
	saved attributes that Surv put in the "inputAttributes"
	object, looking first at the event variable, then time2,
	and finally time.  You can restrict the looking by specifying
	type.
labelLatex constructs suitable LaTeX labels a variable or from the
	label and units arguments, optionally right-justifying
	units if hfill=TRUE.  This is useful when making tables
	when the variable in question is not a column heading.  If x
	is specified, label and units values are extracted from
	its attributes instead of from the other arguments.
Label (actually 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.
llist is like list except that it preserves the names or
  labels of the component variables in the variables label
  attribute.  This can be useful when looping over variables or using
  sapply or lapply. By using llist instead of
  list one can annotate the output with the current variable's name
  or label.  llist also defines a names attribute for the
  list and pulls the names from the arguments' expressions for
  non-named arguments.
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 htmlfig option provides more capabilities when
	making html reports.  prList does not work for regular html
	documents.
putHfig is similar to prList but for a single graphical
	object that is rendered with a 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 table=TRUE table
	captions will be produced instead.  Using expcoll,
	markupSpecs html function expcoll will be used to
	make tables expand upon clicking an arrow rather than always appear.
putHcap is like putHfig except that it
	assumes that users render the graphics or table outside of the
	putHcap call.  This allows things to work in ordinary html
	documents.  putHcap does not handle collapsed text.
plotmathTranslate is a simple function that translates certain
  character strings to character strings that can be used as part of R
  plotmath expressions.  If the input string has a space or percent
  inside, the string is surrounded by a call to plotmath's
  paste function.
as.data.frame.labelled is a utility function that is called by
  [.data.frame.  It is just a copy of as.data.frame.vector.
  data.frame.labelled is another utility function, that adds a
  class "labelled" to every variable in a data frame that has a
  "label" attribute but not a "labelled" class.
relevel.labelled is a method for preserving labels with the relevel function.
reLabelled is used to add a 'labelled' class back to
  variables in data frame that have a 'label' attribute but no 'labelled'
  class.  Useful for changing cleanup.import()'d S-Plus data
  frames back to general form for R and old versions of S-Plus.
label(x, default=NULL, ...)# S3 method for default
label(x, default=NULL, units=plot, plot=FALSE,
      grid=FALSE, html=FALSE, ...)
# S3 method for Surv
label(x, default=NULL, units=plot, plot=FALSE,
      grid=FALSE, html=FALSE, type=c('any', 'time', 'event'), ...)
# S3 method for data.frame
label(x, default=NULL, self=FALSE, ...)
label(x, ...) <- value
# S3 method for default
label(x, ...) <- value
# S3 method for data.frame
label(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)
# S3 method for labelled
print(x, ...)   ## or x - calls print.labelled
Label(object, ...)
# S3 method for data.frame
Label(object, file='', append=FALSE, ...)
llist(..., labels=TRUE)
prList(x, lcap=NULL, htmlfig=0, after=FALSE)
putHfig(x, ..., scap=NULL, extra=NULL, subsub=TRUE, hr=TRUE,
        table=FALSE, file='', append=FALSE, expcoll=NULL)
putHcap(..., scap=NULL, extra=NULL, subsub=TRUE, hr=TRUE,
        table=FALSE, file='', append=FALSE)
plotmathTranslate(x)
data.frame.labelled(object)
# S3 method for labelled
relevel(x, ...)
reLabelled(object)
combineLabels(...)
label returns the label attribute of x, if any; otherwise, "".
label is used
  most often for the individual variables in data frames.  The function
sas.get copies labels over from SAS if they exist.
any object (for plotmathTranslate is a character string). For
		relevel is a factor variable.  For prList is a
		named list.  For putHfig is a graphical object for which a
		print method will render the graphic (e.g., a ggplot2
		or plotly object).
lgoical, where to interact with the object or its components
set to TRUE to append the 'units' attribute (if present)
    to the returned label.  The 'units' are surrounded
    by brackets.  For labelPlotmath and labelLatex is a
		character string containing the units of measurement.  When
		plot is TRUE, units defaults to TRUE.
set to TRUE to return a label suitable for R's plotmath
    facility (returns an expression instead of a character string) if R is
    in effect.  If units is also TRUE, and if both
    'label' and 'units' attributes are present, the
    'units' will appear after the label but in smaller type and
    will not be surrounded by brackets.
if x does not have a 'label' attribute and
    default (a character string) is specified, the label will be
    taken as default.  For labelLatex the default
		is the name of the first argument if it is a variable and not a label.
Currently R's lattice and grid functions do not support
    plotmath expressions for xlab and ylab
    arguments.  When using lattice functions in R, set the
    argument grid to TRUE so that labelPlotmath can
    return an ordinary character string instead of an expression.
set to TRUE to use HTML formatting instead of
		plotmath expressions for constructing labels with units
for Surv objects specifies the type of element for
		which to restrict the search for a label
a character string containing a variable's label
set to TRUE to have labelMathplot return an expression
    for plotting using R's plotmath facility.  If R is not in
    effect, an ordinary character string is returned.
set to TRUE to have labelPlotmath return a
		character string of the form "expression(...)"
LaTeX size for units.  Default is two sizes smaller
		than label, which assumes that the LaTeX relsize
		package is in use.
set to TRUE to right-justify units in the
		field.  This is useful when multiple labels are being put into rows
		in a LaTeX tabular environment, and will cause a problem if
		the label is used in an environment where hfill is not
		appropriate.
set to TRUE to have labelLatex put the
		label in bold face.
set to 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 as.formula
the label of the object, or "".
a data frame
a list of variables or expressions to be formed into a list.
    Ignored for print.labelled.  For relevel is the
		level (a single character string) to become the new reference
		(first) category.  For putHfig and putHcap represents
		one or more character strings that are pasted together, separated by
		a blank.
the name of a file to which to write S source code.  Default is
    "", meaning standard output.  For putHcap, set
		file to FALSE to return a character vector instead of
		writing to file.
set to TRUE to append code generated by Label to file
		file.  Also used for putHfig, putHcap.
set to FALSE to make llist ignore the variables'
		label attribute and  use the variables' names.
an optional vector of character strings corresponding to
		elements in x for 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.
for prList set to 1 to use HTML markup by
		running the object names through markupSpecs$html$cap for
			figure captions.  Set htmlfig=2 to also preface the figure
			caption with "### " so that it will appear in the table of
			contents.
set to TRUE to have prList put names after
		the printed object instead of before
a character string specifying the short (or possibly only) caption.
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 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.
set to FALSE to suppress "### " from being
		placed in front of the short caption.  Set it to different character
		string to use that instead.  Set it to "" to ignore short
		captions entirely.  For example to use second-level headings for the
	table of contents specify subsub="## ".
applies if a caption is present.  Specify FALSE to
		not put a horizontal line before the caption and figure.
set to TRUE to produce table captions instead of
		figure captions
character string to be visible, with a clickable arrow
		following to allow initial hiding of a table and its captions.
		Cannot be used with table=FALSE.
sas.get, describe,
	extractlabs, hlab
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))}
Run the code above in your browser using DataLab