From murdoch at stats.uwo.ca  Thu Nov 19 12:32:38 2009
From: murdoch at stats.uwo.ca (Duncan Murdoch)
Date: Thu, 19 Nov 2009 06:32:38 -0500
Subject: [Rd] Issue when calling deparse(substitute(x)) from C with
 "anonymous" R vectors ?
In-Reply-To: <4B04F65C.2040002@gmail.com>
References: <4B04F65C.2040002@gmail.com>
Message-ID: <4B052CD6.2040904@stats.uwo.ca>

Can you put together a minimal, self contained example, not requiring an 
external system?  This has the symptoms of a bug in the external code 
(e.g. a missing PROTECT), but it is possible it's a bug in R.

Duncan Murdoch

On 19/11/2009 2:40 AM, Laurent Gautier wrote:
> Dear list,
> 
> 
> When calling R from C, what appears like a spurious error can be 
> triggered during the execution of chisq.test(x, y).
> 
> This is happening when the following conditions are met:
> 
> - x and y are "anonymous" C-level R vectors (they do not have a symbol),
> but they are protected from garbage collection
> 
> - x and y are "not too small" (it was experienced as soon as they are 
> longer than 17 elements).
> 
> 
> The error is
> 
> Error in names(dimnames(x)) <- DNAME :
>    'names' attribute [4] must be the same length as the vector [2]
> 
> and can be traced to the use of deparse(substitute(x)) and 
> deparse(substitute(y)) in the R code.
> 
> What seems to be happening is that the deparse(substitute(x)) call
> gives a character vector of length > 1 as soon as x is "not so small".
> 
> To demonstrate this, I am using rpy2 (as the problem was found when using it
> http://sourceforge.net/mailarchive/forum.php?thread_name=4B043CA1.9050500%40salilab.org&forum_name=rpy-list
> ), but it will likely be present in other bridges to R as well.
> 
> 
> #using R-2.10 and rpy2-2.1.dev
>  >>> import rpy2.robjects as robjects
> 
>  >>> f = robjects.r('''function(x) return(deparse(substitute(x)))''')
> 
>  >>> tuple(f(robjects.FloatVector(range(17))))
> ('c(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)',)
> # length 1
>  >>> tuple(f(robjects.FloatVector(range(18))))
> ('c(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17', ')')
> # length 2 !!
> 
> 
> Does it seem to others like an issue present in other bridges as well ?
> 
> 
> 
> L.
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel



[Rd] Issue when calling deparse(substitute(x)) from C with "anonymous" R vectors ?
Duncan Murdoch