[R] getting informative error messages

[Prof Brian Ripley]

It is not clear to me what you want here.

Errors are tagged by a 'call', and f(1:3) is the innermost 'call' (special 
primitives do not set a context and so do not count if you consider '[' 
to be a function).

The message could tell you what the type was, but it does not and we have 
lost the pool of active contributors we once had to submit tested patches 
for things like that.


On Mon, 7 May 2007, Tony Plate wrote:

> Certain errors seem to generate messages that are less informative than
> most -- they just tell you which function an error happened in, but
> don't indicate which line or expression the error occurred in.
>
> Here's a toy example:
>
> > f <- function(x) {a <- 1; y <- x[list(1:3)]; b <- 2; return(y)}
> > options(error=NULL)
> > f(1:3)
> Error in f(1:3) : invalid subscript type
> > traceback()
> 1: f(1:3)
> >
>
> In this function, it's clear that the error is in subscripting 'x', but
> it's not always so immediately obvious in lengthier functions.
>
> Is there anything I can do to get a more informative error message in
> this type of situation?  I couldn't find any help in the section
> "Debugging R Code" in "R-exts" (or anything at all relevant in "R-intro").
>
> (Different values for options(error=...) and different formatting of the
> function made no difference.)
>
> -- Tony Plate
>
> > sessionInfo()
> R version 2.5.0 (2007-04-23)
> i386-pc-mingw32
>
> locale:
> LC_COLLATE=English_United States.1252;LC_CTYPE=English_United
> States.1252;LC_MONETARY=English_United
> States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252
>
> attached base packages:
> [1] "stats"     "graphics"  "grDevices" "utils"     "datasets"  "methods"
> [7] "base"
>
> other attached packages:
> tap.misc
>    "1.0"
> >
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595