[R] help on retrieving output from by( ) for regression

[Marc Schwartz]

Also, looking at the last example in ?by would be helpful:

attach(warpbreaks)
tmp <- by(warpbreaks, tension, function(x) lm(breaks ~ wool, data = x))

# To get coefficients:
sapply(tmp, coef)

# To get residuals:
sapply(tmp, resid)

# To get the model matrix:
sapply(tmp, model.matrix)



To get the summary() output, I suspect that using:

  lapply(tmp, summary)

would yield more familiar output as compared to using:

  sapply(tmp, summary)

The output from the latter might require a bit more "navigation" through
the resultant matrix, depending upon how the output is to be ultimately
used.

HTH,

Marc Schwartz



On Thu, 2005-08-25 at 14:57 +0200, TEMPL Matthias wrote:
> Look more carefully at 
> ?lm 
> at the See Also section ...
> 
> X <- rnorm(30)
> Y <- rnorm(30)
> lm(Y~X)
> summary(lm(Y~X))
> 
> Best,
> Matthias
> 
> 
> > Hi all 
> > 
> > I used a function 
> > > qtrregr <- by(AB, AB$qtr, function(AB) lm(AB$X~AB$Y))
> > 
> > objective is to run a regression on quartery subsets in the 
> > data set AB, having variables X and Y, grouped by variable qtr.
> > 
> > Now i retrieved the output using qtrregr, however it only 
> > showed the coefficients (intercept and B) with out 
> > significant levels and residuals for each qtr. Can some on 
> > help me on how can retrieve the detailed regression output.
> > 
> > rgds
> > 
> > snvk
> >