You can select elements of a matrix using a 2 dimensional matrix that specifies the row/column number of the cells you want to extract:
> c2 <- cbind(seq_len(nrow(c0)), c1) > c2 c1 [1,] 1 2 [2,] 2 2 [3,] 3 1 [4,] 4 2 [5,] 5 1 [6,] 6 1 > d1 <- c0[c2] > d1 [1] -1 -3 12 2 -23 17 See the help page for [ ?'[' ------------------------------------- David L Carlson Department of Anthropology Texas A&M University College Station, TX 77840-4352 -----Original Message----- From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Sergio Fonda Sent: Friday, June 5, 2015 8:47 AM To: John Kane Cc: R-help Subject: Re: [R] Matrix of indexes to extract sparse data in dataframe Thank you, of course but I can't use that form as I told. My question is about the possibility to enter in a dataframe with a matrix of indices and get the corresponding values Thanks again Il 05/giu/2015 15:39, "John Kane" <jrkrid...@inbox.com> ha scritto: > d1 <- apply(c0, 1, min) I think does it. > > John Kane > Kingston ON Canada > > > > -----Original Message----- > > From: sergio.fond...@gmail.com > > Sent: Fri, 5 Jun 2015 15:06:34 +0200 > > To: r-help@r-project.org > > Subject: [R] Matrix of indexes to extract sparse data in dataframe > > > > I would like to avoid a "for loop" to get a vector of data taken from > > rows of a data frame for specific columns. > > An example is the following (I can't apply min to every row of df, this > > is > > just an example): > > > > c0=data.frame(a=c(3,-2,12,7,-23,17) , b=c(-1,-3,14,2,6,19)) > > c1=apply(c0,1,which.min) > >> c1 > > [1] 2 2 1 2 1 1 > > > > I would like to get a result like the following call, but without > > employing a "for loop": > > > > d1=c(c0[1,c1[1]], c0[2,c1[2]], c0[3,c1[3]], c0[4,c1[4]], c0[5,c1[5]], > > c0[6,c1[6]]) > >> d1 > > [1] -1 -3 12 2 -23 17 > > > > Thanks a lot for any help! > > > > ______________________________________________ > > 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. > > ____________________________________________________________ > Can't remember your password? Do you need a strong and secure password? > Use Password manager! It stores your passwords & protects your account. > Check it out at http://mysecurelogon.com/password-manager > > > [[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. ______________________________________________ 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.