Thank you very much! Il 05/giu/2015 15:58, "David L Carlson" <dcarl...@tamu.edu> ha scritto:
> 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. > [[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.
