[R] First Variable in lm

[Liaw, Andy]

You might be trying too hard:

> dat <- data.frame(y=rnorm(10), x1=rnorm(10), x2=rnorm(10))
> fit <- lm(dat)
> summary(fit)

Call:
lm(formula = dat)

Residuals:
     Min       1Q   Median       3Q      Max 
-1.11643 -0.42746 -0.01442  0.55902  1.04890 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)  
(Intercept)   0.7804     0.2700   2.891   0.0233 *
x1            0.7469     0.2925   2.553   0.0379 *
x2           -0.1099     0.2155  -0.510   0.6257  
---
Signif. codes:  0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1 

Residual standard error: 0.8234 on 7 degrees of freedom
Multiple R-Squared: 0.5016,     Adjusted R-squared: 0.3592 
F-statistic: 3.522 on 2 and 7 DF,  p-value: 0.08742 

HTH,
Andy

> From: Christian Hoffmann
> 
> Hi all,
> 
> I just cannot think of how to do it:
> I want to take the first variable (column) of a data frame 
> and regress 
> it against all other variables.
> 
> bla <- function (dat) {
>    reg <- lm(whateverthefirstofthevariablenamesis ~., data=dat)
>    return(reg)
> }
> 
> What kind of function do I have to take instead of the 
> whateverthefirstofthevariablenamesis,
> 
> eval(), substitute(), get(),  ...
> 
> to correctly compute this regression?
> 
> With   lm(get(names(dat)[1] ~., data=dat) there are no 
> errors, but the 
> first variable also shows up among the regressors.
> 
> Thanks for help.
> Christian Hoffmann
> 
> -- 
> Dr.sc.math.Christian W. Hoffmann, 
> http://www.wsl.ch/staff/christian.hoffmann
> Mathematics + Statistical Computing   e-mail: 
> christian.hoffmann at wsl.ch
> Swiss Federal Research Institute WSL  Tel: ++41-44-73922-   
> -77  (office)
> CH-8903 Birmensdorf, Switzerland             -11(exchange), -15  (fax)
> 
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