[R] lmList, tapply() and lm()

[Jonathan Baron]

Here is an example I just did.  I _LOVE_ lmList().  It is such a great
convenience compared to the following.  But right now it doesn't work
for "family=binomial", so I had to do it differently.  This is not
your example, but it should give you an idea.  The [[5]] was because I
was interested only in the 5th coefficient for each subject (the
interaction term).  Note that I used coef() because I was interested
only in the coefficients.

l1g <- by(d1,subject,function(x)
          coef(glm(achoice ~ lnlra*session+lnpodd,data=x,family=binomial))[[5]])


On 02/15/08 11:00, Marc Belisle wrote:
> Howdee,
> 
> *** I know that the lmList() function exists, yet I don't want to use it.
> ***
> 
> Would anyone be kind enough to tell how I can apply the function lm() to
> each level of a given factor so to obtain the intercept and slope for each
> factor level within a matrix?
> 
> For instance, suppose a dataframe containing 3 variables: id, x and y.
> 
> I want to compute the function lm() for each level contained in id, as
> lmList would do...
> 
> Thanks for your time,

-- 
Jonathan Baron, Professor of Psychology, University of Pennsylvania
Home page: http://www.sas.upenn.edu/~baron