Hi Dennis, It worked! this is what I am looking for. Many thanks. Rgds, SNVK _____
From: Dennis Murphy [mailto:djmu...@gmail.com] Sent: Tuesday, January 04, 2011 9:07 PM To: SNV Krishna Cc: r-help@r-project.org Subject: Re: [R] how to subset unique factor combinations from a data frame. 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.
