[R] linear regression "group by"

Ryan Lauritsen ryanlauritsen at gmail.com
Mon Apr 14 19:03:28 CEST 2008

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:
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,

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