Hi: Did you try something like
summdf <- as.data.frame(with(df, table(Commodity, Attribute, Unit))) ? The rows of the table should represent the unique combinations of the three variables.... Here's a simple toy example to illustrate: > x <- sample(LETTERS[1:6], 1000, replace = TRUE) > xx <- sample(letters[1:6], 1000, replace = TRUE) > u <- as.data.frame(table(x, xx)) > dim(u) [1] 36 3 > head(u) x xx Freq 1 A a 26 2 B a 29 3 C a 25 4 D a 25 5 E a 27 6 F a 29 HTH, Dennis On Tue, Jan 4, 2011 at 2:19 AM, SNV Krishna <kris...@primps.com.sg> wrote: > Hi, > > Sorry that my example is not clear. I will give an example of what each > variable holds. I hope this clearly explains the case. > > Names of the dataframe (df) and description > > Year :- Year is calendar year, from 1980 to 2010 > > Country :- is the country name, total no. (levels) of countries is ~ 190 > > Commodity :- Crude oil, Sugar, Rubber, Coffee .... No. (levels) of > commodities is 20 > > Attribute: - Production, Consumption, Stock, Import, Export... Levels ~ 20 > > Unit :- this is actually not a factor. It describes the unit of Attribute. > Say the unit for Coffee (commodity) - Production (attribute) is 60 kgs. > While the unit for Crude oil - Production is 1000 barrels > > Value :- value > > > tail(df, n = 10) // example data// > > Year Country Commodity Attribute Unit > Value > 1991 United Kingdom Wheat, Durum Total Supply (1000 MT) 70 > 1991 United Kingdom Wheat, Durum TY Exports (1000 MT) 0 > 1991 United Kingdom Wheat, Durum TY Imp. from U (1000 MT) 0 > 1991 United Kingdom Wheat, Durum TY Imports (1000 MT) 60 > 1991 United Kingdom Wheat, Durum Yield (MT/HA) 5 > > Wish this is clear. Any suggestion > > Regards, > > SNVK > > -----Original Message----- > From: Petr PIKAL [mailto:petr.pi...@precheza.cz] > Sent: Tuesday, January 04, 2011 4:06 PM > To: SNV Krishna > Cc: r-help@r-project.org > Subject: Odp: [R] how to subset unique factor combinations from a data > frame. > > Hi > > r-help-boun...@r-project.org napsal dne 04.01.2011 05:21:25: > > > Hi All > > > > I have these questions and request members expert view on this. > > > > a) I have a dataframe (df) with five factors (identity variables) and > value > > (measured value). The id variables are Year, Country, Commodity, > Attribute, > > Unit. Value is a value for each combination of this. > > > > I would like to get just the unique combination of Commodity, > > Attribute > and > > Unit. I just need the unique factor combination into a dataframe or a > table. > > I know aggregate and subset but dont how to use them in this context. > > aggregate(Value, list(Comoditiy, Atribute, Unit), function) > > > > > b) Is it possible to inclue non- aggregate columns with aggregate > function > > > > say in the above case > aggregate(Value ~ Commodity + Attribute, data > > = > df, > > FUN = count). The use of count(Value) is just a round about to return > the > > combinations of Commodity & Attribute, and I would like to include > 'Unit' > > column in the returned data frame? > > Hm. Maybe xtabs? But without any example it is only a guess. > > > > > c) Is it possible to subset based on unique combination, some thing > > like this. > > > > > subset(df, unique(Commodity), select = c(Commodity, Attribute, Unit)). > I > > know this is not correct as it returns an error 'subset needs a > > logical evaluation'. Trying various ways to accomplish the task. > > > > Probably sqldf package has tools for doing it but I do not use it so you > have to try yourself. > > df[Comodity==something, c("Commodity", "Attribute", "Unit")] > > can be other way. > > Anyway your explanation is ambiguous. Let say you have three rows with the > same Commodity. Which row do you want to select? > > Regards > Petr > > > > will be grateful for any ideas and help > > > > Regards, > > > > SNVK > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > 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. > [[alternative HTML version deleted]] ______________________________________________ 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.
