From p.dalgaard@biostat.ku.dk  Thu Oct 12 18:37:49 2000
From: p.dalgaard@biostat.ku.dk (Peter Dalgaard BSA)
Date: 12 Oct 2000 19:37:49 +0200
Subject: [Rd] works in R-1.1.1 but not in R-development; why?
In-Reply-To: Ramon Diaz-Uriarte's message of "Thu, 12 Oct 2000 16:16:52 +0200"
References: <00101216345102.00374@ligarto>
Message-ID: <x2hf6ikljm.fsf@blueberry.kubism.ku.dk>

Ramon Diaz-Uriarte <ramon-diaz@teleline.es> writes:

> Dear All,
> 
> A library (PHYLOGR) that passed the usual tests in R-1.1.1 gives errors with
> R-devel; my (mis?)understanding of scoping rules is
> that it should have worked in both. The problems seem related to using the
> name of the data frame for extracting weights or subsets within a function
> call. The problems can be reproduced as follows:
> 
> **********************
> 
> datai <- data.frame( y = rnorm(10), x1 = rnorm(10), x2 = abs(rnorm(10)),
>                     x3 = rep(seq(1,5),2), counter = rep(c(1,2),c(5,5)))
> 
> formula <- as.formula(y ~ x1)
> 
> 
> # the following fails in R-1.2.0 but not in R-1.1.1
> # > Error in eval(expr, envir, enclos) : Object "datos" not found
> lapply(split(datai,datai$counter),
>        function(datos,formula) {lm(formula = formula, data = datos,
>                                    weights = datos$x2)},
>        formula = formula) 

Ow!... This happens because of a change that makes formulas capture
their environment of definition.

A workaround is to explicitly set the environment of the formula to
the current environment, like this:

lapply(split(datai,datai$counter),
       function(datos,formula) {
	  environment(formula)<-environment()
	  lm(formula = formula, data = datos,
                                   weights = datos$x2)
       },
       formula = formula) 

but I bet Luke wants to comment on this...

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907
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[Rd] works in R-1.1.1 but not in R-development; why?
Peter Dalgaard BSA