[R] Max characters from deparse(substitute(.))?

[Spencer Graves]

On 5/5/2014 3:42 PM, William Dunlap wrote:
> Have you looked at the width.cutoff and nlines arguments to deparse?
> width.cutoff controls how long a line can be and it quits producing
> output (saving time and space) after nlines of output are produced.
> You want essentially the following
>     f0 <- function(x, maxChar=20) deparse(x, width.cutoff=maxChar, nlines=1)
> or, to add the '...' to the end if something was cut off
>    f1 <- function(x, maxChar=20) {
>        # deparse warns and uses 65 if maxChar<20, so avoid that.
>        retval <- deparse(x, width.cutoff=max(20, maxChar+1), nlines=1)
>        if (nchar(retval) > maxChar) {
>            retval <- paste0(substring(retval, 1, maxChar), "...")
>        }
>        retval
>    }

Hi, Bill:  Thanks very much.  I could have solved it myself if I had 
known which FMTR.  Thanks again.  Spencer

> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
>
> On Mon, May 5, 2014 at 2:44 PM, Spencer Graves
> <spencer.graves at structuremonitoring.com> wrote:
>>         Is there a standard or or a standard utility to limit the size of
>> deparse(substitute(.))?
>>
>>
>>         Below please find an example of the problem plus one solution.
>> If another solution already exists, I might prefer to use it.
>>
>>
>>         Thanks,
>>         Spencer
>>
>>
>> ##
>> ## Problem
>> ##
>> deparse.x0 <- function(x)deparse(substitute(x))
>> deparse.a <- do.call(deparse.x0, list(letters))
>> nchar(deparse.a) # unacceptable
>>
>> [1] 62 65  4
>>
>>
>> ##
>> ## Better
>> ##
>> deparse.x <- function(x, maxChar=20){
>>     name.x <- deparse(substitute(x))
>>     nch.x <- nchar(name.x)
>>     name2 <- name.x[nch.x>0]
>>     nch2 <- nch.x[nch.x>0]
>>     if((length(name2)>1)){
>>       name2 <- name2[1]
>>     }
>>     if(nch2[1]>maxChar){
>>       name2 <- paste0(substring(name2, 1, maxChar), '...')
>>     }
>>     name2
>> }
>>
>> do.call(deparse.x, list(letters)) # better
>>
>> [1] "c(\"a\", \"b\", \"c\", \"d\"..."
>>
>>
>>
>>
>>          [[alternative HTML version deleted]]
>>
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