deparse
Turn a Parsed Expression into Character Form
Description
Returns a vector of character strings representing the input expression.
Usage
deparse(expr, width.cutoff = 60L,
backtick = mode(expr) %in% c("call", "expression", "(", "function"),
control = c("keepInteger", "showAttributes", "keepNA"), nlines = -1L)
deparse1(expr, collapse = " ", width.cutoff = 500L, ...)
Arguments
| expr |
any expression.
|
| width.cutoff |
the maximum number of characters on a line. Must be between 20 and 500.
the default is 60. Note that a line might be longer if deparse
fails to find a good way to split the expression.
|
| backtick |
a logical flag. If TRUE, symbol names are escaped with backticks
when needed. If FALSE, symbol names are not escaped. This
technique can be useful (and more readable) when you want the result
to be displayed as a label, but it is not possible to parse the
result.
|
| control |
a vector of character strings that indicate which kind of options you are
trying to set. A valid combination includes the following:
- "all"
- "keepInteger"
- "quoteExpressions"
- "showAttributes"
- "useSource"
- "warnIncomplete"
- "delayPromises"
- "keepNA"
- "S_compatible"
- "noSplitLines"
Note that "all" specifies all options on this list except
"delayPromises", "S_compatible", and "noSplitLines".
- If mode(expr) is "call" or "name", and the control with
"quoteExpressions" is set, the result is surrounded by
"quote()".
- If mode(expr) is "call", and control with
"S_compatible" is set, the integer changes to double.
|
| nlines |
the maximum number of lines to return.
|
| collapse |
deparse1(expr, collapse, width.cutoff, ...) calls paste(collapse=collapse, deparse(expr, width.cutoff=width.cutoff, ...)).
|
| ... |
deparse1 passes all unrecognized arguments to deparse.
|
Details
Usually, deparsing expressions to print them is not necessary.
For example, coercing an expression to mode "character" with
the as.character function usually achieves the
same effect in a simpler way. However, as the following two examples demonstrate, there are
differences between deparse and as.character.
In the first example, the value of deparse is shown when you have a character vector
with as many elements as there are lines in the output from dput(expr).
Contrast this with calling as.character, which returns a character
vector the same length as the input object. Most likely, that is not what
you want if you started with an expression object.
In the second example, you want a single character string containing
deparsed code. To get this single character string, use deparse1 (but the string might
not always parse correctly to recover expr).
Value
deparse returns a character vector containing the deparsed expression.
Each element of the character vector corresponds to a line of
output from dput(expr).
deparse1 returns a single character string containing the results of
the corresponding call to deparse pasted together with collapse
pasted between each line.
Differences between Spotfire Enterprise Runtime for R and Open-source R
- Spotfire Enterprise Runtime for R has the extra control parameter noSplitLines.
- In Spotfire Enterprise Runtime for R, deparse currently supports only the control parameters 'keepInteger', 'keepNA', 'showAttributes', 'useSource', and (the Spotfire Enterprise Runtime for R-specific) 'noSplitLines'.
See Also
Examples
ex <- parse(text="mean(1:10)")
deparse(ex)
f <- function(x, y=1) { x+y }
deparse(f)
deparse1(f)