[R] summing up colum values for unique IDs when multiple ID's exist in data frame

Thomas Lumley tlumley at u.washington.edu
Tue May 29 23:54:02 CEST 2007

On Tue, 29 May 2007, Seth Falcon wrote:

> "Young Cho" <young.stat at gmail.com> writes:
>> I have data.frame's with IDs and multiple columns. B/c some of IDs
>> showed up more than once, I need sum up colum values to creat a new
>> dataframe with unique ids.
>> I hope there are some cheaper ways of doing it...  Because the
>> dataframe is huge, it takes almost an hour to do the task.  Thanks
>> so much in advance!
> Does this do what you want in a faster way?

rowsum() should probably be faster (but perhaps not much).


Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle

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