You might want to look at ?table and ?xtab. See also ?tapply for use of general functions (other than just COUNT) with GROUP BY.
HTH, Vadim > -----Original Message----- > From: JFRI (Jesper Frickmann) [mailto:[EMAIL PROTECTED] > Sent: Friday, April 02, 2004 1:06 PM > To: [EMAIL PROTECTED] > Subject: [R] Doing SQL GROUP BY in R > > > I want a list of the number of times some factor levels > appear together, similar to the following SQL statement: > > SELECT A, B, COUNT(C) FROM TBL GROUP BY A, B > > How do I do that with a data.frame in R? > > Thanks, > Jesper Frickmann > Statistician, Quality Control > Novozymes North America Inc. > 77 Perry Chapel Church Road > Franklinton, NC 27525 > USA > Tel. +1 919 494 3266 > > > [[alternative HTML version deleted]] > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo> /r-help > PLEASE > do read the posting guide! > http://www.R-project.org/posting-guide.html > ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
