[R] linear regression "group by"

From: Ryan Lauritsen <ryanlauritsen_at_gmail.com>
Date: Mon, 14 Apr 2008 13:03:28 -0400


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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