[R] using a string as the formula in rlm

[Liaw, Andy]

It may help you to read Bill Venables' column in R News
http://cran.r-project.org/doc/Rnews/Rnews_2002-2.pdf, pages 24-26.

Andy

> -----Original Message-----
> From: Rajarshi Guha [mailto:rxg218 at psu.edu] 
> Sent: Thursday, October 02, 2003 11:25 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] using a string as the formula in rlm
> 
> 
> Hi,
>  I am trying to build a series of rlm models. I have my data 
> frame and the models will be built using various coulmns of 
> the data frame.
> 
> Thus a series of models would be
> 
> m1 <- rlm(V1 ~ V2 + V3 + V4, data)
> m2 <- rlm(V1 ~ V2 + V5 + V7, data)
> m3 <- rlm(V1 ~ V2 + V8 + V9, data)
> 
> I would like to automate this. Is it possible to use a string 
> in place of the formula?
> 
> I tried doing:
> 
> fmla <- sprintf('V1 ~ V%g + V%g + V%g',2,3,4)
> m1 <-rlm(fmla,data)
> 
> I get:
> 
> Error in qr(x) : NA/NaN/Inf in foreign function call (arg 1)
> In addition: Warning message:
> NAs introduced by coercion
> 
> I can understand why this method results in the error but is 
> there any way to get around this?
> 
> Thanks,
> 
> -------------------------------------------------------------------
> Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
> GPG Fingerprint: 0CCA 8EE2 2EEB 25E2 AB04 06F7 1BB9 E634 9B87 56EE
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