Try:

 by(x, list(x$STNID), function(.x)lm(TEMP ~ DEWP, data = .x))

On Mon, Apr 14, 2008 at 2:03 PM, Ryan Lauritsen <ryanlauritsen@gmail.com>
wrote:

> Hi all.  I'm brand new to R.
>
> My dataset (stored in MySQL) is a list of weather stations in rows by
> year with various weather variables in columns, for example:
> STNID     YEAR  TEMP  DEWP
> station1    1990   54       50
> station1    1991   23       10
> station1    1992   34       18
> station2    1990   45       41
> station2    1991   32       25
> station2    1992   21       11
>
> I'm trying to run linear regression and get the basic output (i.e.
> intercept, slope, and significance) for each station.  I'm able to run
> the regression on the entire dataset using:
> lm(TEMP~DEWP, data=select)
> But is there a way to aggregate the data ("group by" in MySQL) by
> STNID during the regression?  Ideally I would just have a list of
> stations and their approriate summary output, which I could use for
> further analysis.
>
> I've searched the manual, etc. for solutions, but have been
> unsuccessful.  Any assistance is greatly appreciated.
>
> Thank you,
> Ryan
>
> ______________________________________________
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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.
>



-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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