Hello: As someone making the move from STATA to R, I'm finding it difficult at times to perform basic tasks in R, so forgive me if I've missed an obvious and easily obtained solution to my problem. I've searched the help guides and the archives and have not been able to find a solution that works.
I have a data frame with thousands of observations that looks something like this: YEAR MONTH DAY COUNTRY REGION PROVINCE CITY 1994 1 22 Sri Lanka South Asia Northern (Province) Pungudutivu 1994 1 25 Sri Lanka South Asia Central (Province) Kandy 1994 2 26 Sri Lanka South Asia Central (Province) Kandy 1994 2 28 Sri Lanka South Asia Eastern (Province) Wakianeri 1994 6 28 Sri Lanka South Asia Eastern (Province) Valachenai 1994 6 31 Sri Lanka South Asia Central (Province) Kandy 1995 3 1 Sri Lanka South Asia North (Province) Kilinochchi 1995 3 6 Sri Lanka South Asia Western (Province) Colombo 1995 7 15 Sri Lanka South Asia Northern (Province) Mankulam 1995 7 23 Sri Lanka South Asia Northern (Province) Point Pedro 1995 9 25 Sri Lanka South Asia Northern (Province) Kilali ... What I would like to do is to calculate the total number of observations by unique combinations of the values of (some of the) variables above. For example, I would like to know how many observations (i.e. rows) have the values YEAR==1994 and MONTH==1. In the end, I'd like a table that looks like this: YEAR MONTH #OBS 1994 1 2 1994 2 2 1994 3 0 1994 4 0 1994 5 0 1994 6 2 1994 7 0 1994 8 0 1994 9 0 1994 10 0 1994 11 0 1994 12 0 1995 1 0 1995 2 0 1995 3 2 1995 4 0 ... I do need to fill out the table with all the possible combinations, even where there are no observations with that combination in the data set. At first, it seemed like this would not be think that aggregate is probably the way to go, but there doesn't seem to be an appropriate summary function (FUN) available. Thanks in advance for any help in this matter, Josip ______________________________________________ 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.
