From thomas@biostat.washington.edu  Thu Oct 12 18:35:03 2000
From: thomas@biostat.washington.edu (Thomas Lumley)
Date: Thu, 12 Oct 2000 10:35:03 -0700 (PDT)
Subject: [Rd] works in R-1.1.1 but not in R-development; why?
In-Reply-To: <x2hf6ikljm.fsf@blueberry.kubism.ku.dk>
Message-ID: <Pine.GSO.4.21.0010121033220.7271-100000@atlas.biostat.washington.edu>

On 12 Oct 2000, Peter Dalgaard BSA wrote:

> 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:

There's a much simpler workaround

lapply(split(datai,datai$counter),function(dataos,formula) lm(formula,
  	data=datos,weights=x2), formula=formula)

because the weights will first be looked for in the data= argument

	-thomas

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[Rd] works in R-1.1.1 but not in R-development; why?
Thomas Lumley