[R] debugging a code

[Liaw, Andy]

Well, you can insert `browser()' right above the offending line, then run
the code again.  It will stop with the `browse>' prompt right before that
line.  You can then check which value(s) give you the problem.

Have you tried Mark Bravington's `debug' package on CRAN?  There's an
article on it in the most recent issue of R News.

Andy

> From: Fred J.
> 
> Hello
> just learned HowTo but R, reminded me with the way
> Perl does it but with much less on-line commands, R
> "AFAIK" has n, c, Q and where and cann't debug outside
> the {}. 
> 
> 1) is there a more versatile/flexable debugging method
> for R?
> 
> I have saved 2 functions in an ASCII file "digfun".
> "getdata" function calls "squash" function and both
> use loops. In another file.R I have
> 
> source("digfun")
> debug(getdata)
> data <- getdata("c:/data/")
> 
> Browse[1]> c
> Error in if (d[i, "V3"] == d[i + 1, "V3"] && d[i,
> "V4"] == d[i + 1, "V4"] &&  : 
> 	missing value where TRUE/FALSE needed
> > traceback()
> 2: squash(dt1)
> 1: getdata("c:/data/")
> > 
> to dubug this I need to know the value of some
> variable at this particular loop/sub-fun loop case,
> and since the dubuger terminated by showing ">"
> prompt, how then I am going to debug this error?
> 
> thanks for helping
> 
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