[R] Problem with the step() function
ripley@stats.ox.ac.uk
ripley at stats.ox.ac.uk
Mon Mar 24 18:46:37 CET 2003
Use R-devel, where this has been changed and your example works.
On Mon, 24 Mar 2003, Luis Torgo wrote:
> Dear all,
> I'm having some problems with using the step() function inside another
> function. I think it is an environment problem but I do not know how to
> overcome it. Any suggestions are appreciated.
>
> I've prepared a simple example to illustrate my problem:
>
> > library(MASS)
> > data(Boston)
> > my.fun <- function(dataset) {
> + l <- lm(medv ~ .,data=dataset)
> + final.l <- step(l)
> + }
> > model <- my.fun(Boston)
> Start: AIC= 1589.64
> medv ~ crim + zn + indus + chas + nox + rm + age + dis + rad +
> tax + ptratio + black + lstat
>
> Df Sum of Sq RSS AIC
> - age 1 0.1 11078.8 1587.6
> - indus 1 2.5 11081.3 1587.8
> <none> 11078.8 1589.6
> - chas 1 219.0 11297.8 1597.5
> - tax 1 242.3 11321.0 1598.6
> - crim 1 243.2 11322.0 1598.6
> - zn 1 257.5 11336.3 1599.3
> - black 1 270.6 11349.4 1599.9
> - rad 1 479.2 11557.9 1609.1
> - nox 1 487.2 11565.9 1609.4
> - ptratio 1 1194.2 12273.0 1639.4
> - dis 1 1232.4 12311.2 1641.0
> - rm 1 1871.3 12950.1 1666.6
> - lstat 1 2410.8 13489.6 1687.3
> Error in model.frame.default(formula = medv ~ crim + zn + indus + chas + :
> Object "dataset" not found
>
> Apparently the step() function is not able to find the "dataset" object which
> is created inside the my.fun() function.
>
> My system information:
> > R.version
> _
> platform i686-pc-linux-gnu
> arch i686
> os linux-gnu
> system i686, linux-gnu
> status
> major 1
> minor 6.1
> year 2002
> month 11
> day 01
> language R
>
> Thank you for any hints.
>
>
--
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
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