On Apr 24, 2010, at 8:59 AM, Shubha Vishwanath Karanth wrote: > Hi, > > > > Let s be a dataframe. > > > >> s > > A B C > > 0 0 1 > > 1 0 1 > > 1 0 1 > > 0 0 1 > > 1 0 1 > > 0 1 1 > > 0 1 1 > > 0 1 1 > > 0 0 1 > > > >> tab1=table(s[,c(1,2)]) > >> tab1 > > B > > A 0 1 > > 0 3 3 > > 1 3 0 > > > >> tab2=table(s[,c(1,3)]) > >> tab2 > > C > > A 1 > > 0 6 > > 1 3 > > > > > > The problem is I need to access frequency corresponding to (0,0). > tab1[1] will give me the correct value while tab2[1] will not give the > frequency which I expected. So, is there a possibility in the table > command to have the order of tab1 and tab2 being equal? (here 2*2). May > be by filling in the appropriate value as 0 or NA? > > > > Thanks, > > Shubha
In this case, 'C' has no 0's, so that value is not considered in the tabulation in the second table. If you coerce each column to a factor with common levels, then you can obtain consistent formats for the output of table. Even though there are no 0's in 'C', that 'C' as a factor now has levels of 0 and 1, they will both be included in the table() output. s.new <- data.frame(lapply(s, factor, levels = 0:1)) > str(s.new) 'data.frame': 9 obs. of 3 variables: $ A: Factor w/ 2 levels "0","1": 1 2 2 1 2 1 1 1 1 $ B: Factor w/ 2 levels "0","1": 1 1 1 1 1 2 2 2 1 $ C: Factor w/ 2 levels "0","1": 2 2 2 2 2 2 2 2 2 > s.new A B C 1 0 0 1 2 1 0 1 3 1 0 1 4 0 0 1 5 1 0 1 6 0 1 1 7 0 1 1 8 0 1 1 9 0 0 1 > table(s.new[, c(1, 2)]) B A 0 1 0 3 3 1 3 0 > table(s.new[, c(1, 3)]) C A 0 1 0 0 6 1 0 3 See ?factor, ?lapply and ?data.frame HTH, Marc Schwartz ______________________________________________ [email protected] 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.
