It is possible to do without loops if you start by calculating the totals. Then is just aggregating and merging data.
Best regards, Thierry set.seed(21) n.country <- 5 average.price <- runif(n.country, max = 200) price <- expand.grid( Product = 1:10, Country = factor(LETTERS[seq_len(n.country)]), Year = 2000:2010 ) price$Price <- rnorm(nrow(price), mean = average.price[price$Country], sd = 30) #number and sum of all prices of the product over all countries and years total.product <- aggregate( cbind(Price, N = 1) ~ Product, data = price, FUN = sum ) #number and sum of all prices of the product per country over all years total.product.country <- aggregate( cbind(Pricec = Price, Nc = 1) ~ Product + Country, data = price, FUN = sum ) #merge both tables combined.price <- merge(total.product, total.product.country) with(combined.price, Price / N) #average price with(combined.price, Pricec / Nc) #average price per country with(combined.price, (Price - Pricec)/ (N - Nc)) #average price in the other countries ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance Kliniekstraat 25 1070 Anderlecht Belgium + 32 2 525 02 51 + 32 54 43 61 85 thierry.onkel...@inbo.be www.inbo.be To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey -----Oorspronkelijk bericht----- Van: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] Namens PIKAL Petr Verzonden: vrijdag 1 augustus 2014 15:18 Aan: Lingyi Ma CC: r-help@r-project.org Onderwerp: Re: [R] How to avoid the three loops in R? Hi I do not see any solution without loops but maybe others find it. I think that you can do it in one loop. Best structure for loop will be list. In each cycle you will compute matrix with diagonal NA mat<-matrix(1,nrow=number of items, ncol=number of items) diag(mat) <- NA apply(price chunk * mat, 2, mean, na.rm=T) So when I named your example as temp I get fac <- interaction(factor(temp$Product), factor(temp$Year_Month), drop=T) lll <- split(temp, fac) for( i in 1:length(lll)) { mat <- matrix(1, nrow=nrow(lll[[i]]), ncol= nrow(lll[[i]])) diag(mat) <- NA lll[[i]]$others <- apply(mat*lll[[i]][,3], 2, mean, na.rm=T) } > lll $`1.201204` Country Product Price Year_Month others 1 AE 1 20 201204 24 2 DE 1 20 201204 24 3 CN 1 28 201204 20 $`2.201204` Country Product Price Year_Month others 4 AE 2 28 201204 25 5 DE 2 28 201204 25 6 CN 2 22 201204 28 $`3.201204` Country Product Price Year_Month others 7 AE 3 28 201204 28 8 CN 3 28 201204 28 $`1.201205` Country Product Price Year_Month others 9 AE 1 20 201205 24 10 DE 1 20 201205 24 11 CN 1 28 201205 20 $`2.201205` Country Product Price Year_Month others 12 AE 2 28 201205 28 13 DE 2 28 201205 28 I did not check speed but it shall be OK. Regards Petr > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Lingyi Ma > Sent: Friday, August 01, 2014 1:42 PM > To: r-help@r-project.org > Subject: [R] How to avoid the three loops in R? > > I have the following data set: > > Country Product Price Year_Month > AE 1 20 201204 > DE 1 20 201204 > CN 1 28 201204 > AE 2 28 201204 > DE 2 28 201204 > CN 2 22 201204 > AE 3 28 201204 > CN 3 28 201204 > AE 1 20 201205 > DE 1 20 201205 > CN 1 28 201205 > AE 2 28 201205 > DE 2 28 201205 > > I want to create the one more column which is "The average price of > the product in other areas". > in other word, for each month, for each product, I calculate the > average of such product in the other area. > > I want sth like: > > Country Product Price Year_Month Price_average_In_Other_area > AE 1 20 201204 14 > AE 2 28 201204 25 > > Please avoid the three for loop, I have tried and it never end. I have > 1070427 rows. Is there better way to speed up my program? > > [[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. ________________________________ Tento e-mail a jakékoliv k němu připojené dokumenty jsou důvěrné a jsou určeny pouze jeho adresátům. Jestliže jste obdržel(a) tento e-mail omylem, informujte laskavě neprodleně jeho odesílatele. Obsah tohoto emailu i s přílohami a jeho kopie vymažte ze svého systému. Nejste-li zamýšleným adresátem tohoto emailu, nejste oprávněni tento email jakkoliv užívat, rozšiřovat, kopírovat či zveřejňovat. Odesílatel e-mailu neodpovídá za eventuální škodu způsobenou modifikacemi či zpožděním přenosu e-mailu. 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