[R] using a string as the formula in rlm

[Rajarshi Guha]

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,

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Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
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