[R] using a string as the formula in rlm

[Spencer Graves]

Have you considered the following: 

      fmla <- formula(sprintf('V1 ~ V%g + V%g + V%g',2,3,4))

hope this helps.  spencer graves

Rajarshi Guha wrote:

>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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