Sorry the new column in DF2 should be called FreqD instead of FreqA. How can I get DF2 with aggregate?
Gang On Jan 7, 2008, at 2:38 PM, Gang Chen wrote: > Yes, I misstated it when I said that I would keep B and C. I want to > collapse column A, but count the frequency of D as a new column in > the new dataframe DF2 while collapsing A. The rows of columns B, C, > and D of course would be reduced because of A collapsing. > > For example, if dataframe DF is > > A B C D > A1 B1 C1 D1 > A1 B2 C1 D1 > A1 B1 C1 D1 > A1 B2 C2 D2 > A2 B1 C1 D1 > A1 B2 C2 D2 > A1 B1 C2 D2 > A2 B2 C1 D1 > A1 B1 C2 D2 > A2 B2 C1 D1 > ...... > > I would like to have a new dataframe DF2 > > B C D FreqA > B1 C1 D1 6 > B1 C1 D2 31 > B1 C2 D1 8 > B1 C2 D2 14 > B2 C1 D1 12 > B2 C1 D2 43 > B2 C2 D1 23 > B2 C2 D2 43 > > Thanks, > Gang > > > > On Jan 7, 2008, at 2:06 PM, Duncan Murdoch wrote: > >> On 1/7/2008 1:28 PM, Gang Chen wrote: >>> I have a dataframe DF with 4 columns (variables) A, B, C, and D, >>> and want to create a new dataframe DF2 by keeping B and C in DF >>> but counting the frequency of D while collapsing A. I tried >>> by(DF$D, list(DF$B, DF$C), FUN=summary) >>> but this is not exactly what I want. What is a good way to do it? >> >> I think you can't do that. If you want to keep B and C, then you >> can't reduce the number of rows, but "collapsing A" sounds like you >> want fewer rows. >> >> Perhaps if you posted a simple before and after example? >> >> Duncan Murdoch > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting- > guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
