Please read the posting guide and include a standalone example.
Maybe you want something like the results from
lm(weight ~ Time, data = ChickWeight, subset = Diet==1)
lm(weight ~ Time, data = ChickWeight, subset = Diet==2)
## ... etc ...
Then you could do
(m <- lm(weight ~ Time*Diet, data = ChickWeight))
To get the Diet==2 coefficients from above you could use something like
sum(coef(m)[c("(Intercept)", "Diet2")]) # Intercept
sum(coef(m)[c("Time", "Time:Diet2")]) # Slope
Hope this helps a little.
Allan
On 12/08/2010 17:11, JesperHybel wrote:
I have a simple dataset of a numerical dependent Y, a numerical independent X
and a categorial variable Z with three levels. I want to do linear
regression Y~X for each level of Z. How can I do this in a single command
that is without using lm() applied three isolated times?
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
