deparse {base}R Documentation

Expression Deparsing


Turn unevaluated expressions into character strings.


deparse(expr, width.cutoff = 60L,
        backtick = mode(expr) %in% c("call", "expression", "(", "function"),
        control = c("keepNA", "keepInteger", "niceNames", "showAttributes"),
        nlines = -1L)

deparse1(expr, collapse = " ", width.cutoff = 500L, ...)



any R expression.


integer in [20, 500] determining the cutoff (in bytes) at which line-breaking is tried.


logical indicating whether symbolic names should be enclosed in backticks if they do not follow the standard syntax.


character vector (or NULL) of deparsing options. See .deparseOpts.


integer: the maximum number of lines to produce. Negative values indicate no limit.


a string, passed to paste().


further arguments passed to deparse().


These functions turn unevaluated expressions (where ‘expression’ is taken in a wider sense than the strict concept of a vector of mode and type (typeof) "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 = c("all", "hexDigits") comes closest to making deparse() an inverse of parse() (but we have not yet seen an example where "all", now including "digits17", would not have been as good). However, not all objects are deparse-able even with these options and a warning will be issued if the function recognizes that it is being asked to do the impossible.

Unless control contains "digits17" or "hexDigits", (or "all" or "exact" which include one of these), 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.

deparse1() is a simple utility added in R 4.0.0 to ensure a string result (character vector of length one), typically used in name construction, as deparse1(substitute(.)).


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.

Attributes named dim, dimnames, levels, names and tsp are deparsed to .Dim, .Dimnames, .Label, .Names and .Tsp as part of calls to structure, apparently for historical compatibility with S. This is likely to change in future.


Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

.deparseOpts for available control settings; dput() and dump() for related functions using identical internal deparsing functionality.

substitute, parse, expression.

Quotes for quoting conventions, including backticks.


require(stats); require(graphics)

deparse(args(lm), width.cutoff = 500)

myplot <- function(x, y) {
    plot(x, y, xlab = deparse1(substitute(x)),
               ylab = deparse1(substitute(y)))

e <- quote(`foo bar`)
deparse(e, backtick = TRUE)
e <- quote(`foo bar`+1)
deparse(e, control = "all") # wraps it w/ quote( . )

[Package base version 4.1.2 Index]