Re: [R] using string as variable name in model

From: Thomas Lumley <tlumley_at_u.washington.edu>
Date: Fri, 04 Jun 2010 08:47:50 -0700 (PDT)

I think you're looking for the update() function.

    -thomas

On Thu, 3 Jun 2010, Roni Kobrosly wrote:

> Hi,
>
> I made a small table of strings that will serve as variable names for lm models I will run. The table looks like this:
>
>> varnames
> num name
> 1 1 zCANTAB_log_IED_totaltrials
> 2 2 zCANTAB_log_IED_preED
> 3 3 zCANTAB_logPALerrors
> 4 4 zCANTAB_PALstages
> 5 5 zCANTAB_logRTI
> 6 6 zCANTAB_RVP_Totalmisses
> 7 7 zCANTAB_log_RVP_falsealarm
> 8 8 zCANTAB_DMS_12000
> 9 9 zCANTAB_PRM_Percent
> 10 10 zCANTAB_SRM_Percent
> 11 11 zCANTAB_sqrt_SWM_within
> 12 12 zCANTAB_sqrt_SWM_Total
> 13 13 zSS_WJ_PC
> 14 14 zSS_WJ_CALC
> 15 15 zSS_WJ_LW
> 16 16 zSS_WJ_AP
> 17 17 zSS_WJ_MF
>
>
> What I'm trying to do is
>
>
> varnames[1,2] -> outcome
>
> lm(outcome ~ income + covariate1 + coviarate2, data=my.data) -> model
>
> I get the following error message:
> "Error in model.frame.default(formula = outcome ~ Hollings_Enroll + Child_sex + :
> variable lengths differ (found for 'Hollings_Enroll')"
>
> But when I run the model:
> lm(zCANTAB_log_IED_totaltrials ~ income + covariate1 + coviarate2, data=my.data) -> model
>
> it works fine. Eventually, once I resolve this, I'd like to make a custom R function to automatically generate 17 regression models with these 17 outcome variable strings. Do you have any ideas how to resolve this error?
>
> Thanks!
> -Roni
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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>

Thomas Lumley			Assoc. Professor, Biostatistics
tlumley_at_u.washington.edu	University of Washington, Seattle

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