Newbie question about "grouping"
Some useful commands are:
by(), aggregate(), ave(), split().
eg
by(market_value, account_id, sum)
-thomas
On Wed, 28 Jan 2009, Rixon, John C. wrote:
Hi folks: I am a SQL guy who just downloaded and installed R yesterday. I am trying to evaluate some "complex" aggregations we are currently performing with Syncsort (and have tried in Oracle) with R. I have loaded data in a dataframe and have performed some of the simple aggregations on a subset of data. What I do not see how to do though, is to "group" the aggregations on a particular key value (e.g., sum market_value over account_id). If you can point me in the right direction I'd very much appreciate it. Thanks! John [[alternative HTML version deleted]]
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Thomas Lumley Assoc. Professor, Biostatistics tlumley at u.washington.edu University of Washington, Seattle