| deparse {base} | R Documentation |
Turn unevaluated expressions into character strings.
deparse(expr, width.cutoff = 60L,
backtick = mode(expr) %in%
c("call", "expression", "(", "function"),
control = c("keepInteger", "showAttributes", "keepNA"),
nlines = -1L)
expr |
any R expression. |
width.cutoff |
integer in [20, 500] determining the cutoff (in bytes) at which line-breaking is tried. |
backtick |
logical indicating whether symbolic names should be enclosed in backticks if they do not follow the standard syntax. |
control |
character vector of deparsing options. See
|
nlines |
integer: the maximum number of lines to produce. Negative values indicate no limit. |
This function turns unevaluated expressions (where ‘expression’
is taken in a wider sense than the strict concept of a vector of mode
"expression" used in expression) into character
strings (a kind of inverse to parse).
A typical use of this is to create informative labels for data sets
and plots. The example shows a simple use of this facility. It uses
the functions deparse and substitute to create labels
for a plot which are character string versions of the actual arguments
to the function myplot.
The default for the backtick option is not to quote single
symbols but only composite expressions. This is a compromise to
avoid breaking existing code.
Using control = "all" comes closest to making deparse()
an inverse of parse(). However, not all objects are
deparse-able even with this option and a warning will be issued if the
function recognizes that it is being asked to do the impossible.
Numeric and complex vectors are converted using 15 significant digits:
see as.character for more details.
width.cutoff is a lower bound for the line lengths: deparsing a
line proceeds until at least width.cutoff bytes have
been output and e.g. arg = value expressions will not be split
across lines.
To avoid the risk of a source attribute out of sync with the actual function definition, the source attribute of a function will never be deparsed as an attribute.
Deparsing internal structures may not be accurate: for example the
graphics display list recorded by recordPlot is not
intended to be deparsed and .Internal calls will be shown as
primitive calls.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
substitute,
parse,
expression.
Quotes for quoting conventions, including backticks.
require(stats); require(graphics)
deparse(args(lm))
deparse(args(lm), width = 500)
myplot <-
function(x, y) {
plot(x, y, xlab = deparse(substitute(x)),
ylab = deparse(substitute(y)))
}
e <- quote(`foo bar`)
deparse(e)
deparse(e, backtick = TRUE)
e <- quote(`foo bar`+1)
deparse(e)
deparse(e, control = "all")