Thanks, Richard. But if the data cannot fill the constructed data frame, will there be NA values?
On Fri, Jan 6, 2017 at 10:07 PM, Richard M. Heiberger <r...@temple.edu> wrote: > Incrementally increasing the size of an array is not efficient in R. > The recommended technique is to allocate as much space as you will > need, and then fill it. > > > system.time({tmp <- 1:5 ; for (i in 1:1000) tmp <- rbind(tmp, 1:5)}) > user system elapsed > 0.011 0.000 0.011 > > dim(tmp) > [1] 1001 5 > > system.time({tmp <- matrix(NA, 1001, 5); for (i in 1:1001) tmp[i,] <- > 1:5}) > user system elapsed > 0.001 0.000 0.001 > > dim(tmp) > [1] 1001 5 > > On Fri, Jan 6, 2017 at 11:46 PM, lily li <chocol...@gmail.com> wrote: > > Hi Rui, > > > > Thanks for your reply. Yes, when I tried to rbind two dataframes, it > works. > > However, if there are more than 50, it got stuck for hours. When I tried > to > > terminate the process and open the csv file separately, it has only one > > data frame. What is the problem? Thanks. > > > > > > On Fri, Jan 6, 2017 at 11:12 AM, Rui Barradas <ruipbarra...@sapo.pt> > wrote: > > > >> Hello, > >> > >> Works with me: > >> > >> set.seed(6574) > >> > >> pre.mat = data.frame() > >> for(i in 1:10){ > >> mat.temp = data.frame(x = rnorm(5), A = sample(LETTERS, 5, TRUE)) > >> pre.mat = rbind(pre.mat, mat.temp) > >> } > >> > >> nrow(pre.mat) # should be 50 > >> > >> > >> Can you give us an example that doesn't work? > >> > >> Rui Barradas > >> > >> > >> Em 06-01-2017 18:00, lily li escreveu: > >> > >>> Hi R users, > >>> > >>> I have a question about filling a dataframe in R using a for loop. > >>> > >>> I created an empty dataframe first and then filled it, using the code: > >>> pre.mat = data.frame() > >>> for(i in 1:10){ > >>> mat.temp = data.frame(some values filled in) > >>> pre.mat = rbind(pre.mat, mat.temp) > >>> } > >>> However, the resulted dataframe has not all the rows that I desired > for. > >>> What is the problem and how to solve it? Thanks. > >>> > >>> [[alternative HTML version deleted]] > >>> > >>> ______________________________________________ > >>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > >>> https://stat.ethz.ch/mailman/listinfo/r-help > >>> PLEASE do read the posting guide http://www.R-project.org/posti > >>> ng-guide.html > >>> and provide commented, minimal, self-contained, reproducible code. > >>> > >>> > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > > 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 -- To UNSUBSCRIBE and more, see 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.