Hi see in line
> -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Kristi Glover > Sent: Friday, March 28, 2014 7:04 PM > To: R-help > Subject: [R] starta.sampling with many (1000 times) and average them > > Hi R Users, > I was trying to select a sample with columns (measured data) by > stratum. I was able to select rows by stratum. But, I wanted to repeat > this procedures 1000 and want to take an average from the 1000 times. > I think it is different than bootstraping since I wanted to select > (rondomly) row with many variable at a time and repeat 1000 times > then,average them. > #----------------------------- > I put here an example > > raw=structure(list(watershed = structure(c(1L, 1L, 1L, 1L, 1L, 1L, > 1L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("A", "B"), class = "factor"), > year = c(2001, 2001, 2002, 2002, 2002, 2002, 2002, 2001, > 2001, 2001, 2002, 2002, 2002), sp1 = c(18.38, 29.1, 90.72, > 16.12, 49.12, 20.81, 65.1, 1.87, 72.99, 93.45, 38.44, 67.13, > 45.71), sp2 = c(46.46, 94, 86.87, 46.91, 21.41, 92.82, 87.75, > 16.18, 18.16, 18.76, 19.26, 52.73, 49.09), sp3 = c(86.9, > 62.82, 74.32, 75.49, 20.17, 58.84, 16.51, 44.14, 44.39, 32.36, > 53.28, 67.42, 33.37)), .Names = c("watershed", "year", "sp1", > "sp2", "sp3"), class = "data.frame", row.names = c(NA, -13L)) > > raw$group<-paste(as.character(raw$watershed),as.character(raw$year), > sep="|") > > # strata.sampling ----- > strata.sampling <- function(data, group,size, method = NULL) { > require(sampling) > if (is.null(method)) method <- "srswor" > if (!method %in% c("srswor", "srswr")) > stop('method must be "srswor" or "srswr"') > temp <- data[order(data[[group]]), ] > ifelse(length(size) > 1, > size <- size, > ifelse(size < 1, > size <- round(table(temp[group]) * size), > size <- rep(size, times=length(table(temp[group]))))) > strat = strata(temp, stratanames = names(temp[group]), > size = size, method = method) > getdata(temp, strat) > } > #--------------- > attach(raw) > test1<-strata.sampling(raw, 'group', 1)# select 1 row by watershed and > year > test2<-strata.sampling(raw, 'group', 1)# select 1 row by watershed and > year > test3<-strata.sampling(raw, 'group', 1)# select 1 row by watershed and > year > test4<-strata.sampling(raw, 'group', 1)# select 1 row by watershed and > year > ... > ... > ... > # here I wanted to repeat this procedure 1000 times Use list object for test test <- vector("list", 1000) after that you can make a for cycle for (i in 1:1000) { test[[i]] <- strata.sampling(raw, 'group', 1) } > > test1000<-strata.sampling(raw, 'group', 2)# select 1 row by watershed > and year > > # and then average of this 1000 tables > > testA<-average(test1[,3:5],test2[,3:5],test3[,3:5],.....test1000[,3:5]) What is average? Mean? You want to average all values from those 3 columns from all tables to one number? result <- 0 for (i in 1:1000) { temp <- mean(as.matrix(test[[i]][,3:5])) result <- temp + result } testA <- result/1000 Alternatively you can make one data frame from the list test.d <- do.call(rbind, test) and use aggregate, ave or other summary functions > Inform<-subset(test1, select=c(1,2,6,9) > FinalData<-data.frame(Inform, testA) > > Would you give me some suggestion on how I can make a loop to repeat > this procedures and average them. Please be more specific in your request. Final part is ambiguous. Regards Petr > > Thanks > > [[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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