Combining several regressions

Hadley Wickham <h.wickham at auckland.ac.nz> writes:

For example, I want to fit separate loess regressions for each value
of some conditioning value.  I can do the regressions with
by(data.frame, conditioning.variable, function(subset) { loess(y ~ x,
subset) })  but I'm at a loss as how to get the fitted values out and
match them up with the rows in the original dataset.

Any suggestions?

[Untested!]

b <- by(data.frame, conditioning.variable, 
        function(subset) { loess(y ~ x, subset) })

unsplit(lapply(b,fitted), conditioning.variable)

You might need to replace the by() by an

  lapply(split(data.frame,cond.var), FUN)

construction, but it doesn't look like it should be necessary.

O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
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