On May 29, 2014, at 11:22 AM, Marc Schwartz <marc_schwa...@me.com> wrote:
> > On May 29, 2014, at 11:02 AM, Olivier Charansonney > <olivier.charanson...@orange.fr> wrote: > >> Hello, >> >> I would like to extract the value in row 1 corresponding to the maximum in >> row 2 >> >> >> >> Array W >> >> [,1] [,2] [,3] [,4] [,5] [,6] [,7] >> [,8] [,9] [,10] >> >> [1,] 651.00000 651.00000 651.00000 651.00000 651.00000 651.00000 651.00000 >> 119.00000 78.00000 78.00000 >> >> [2,] 13.24184 13.24184 13.24184 13.24184 13.24184 13.24184 13.24184 >> 16.19418 15.47089 15.47089 >> >>> valinit<-max(W[2,]) >> >>> valinit >> >> [1] 16.19418 >> >> How to obtain ‘119’ >> >> Thanks, > > > Hi, > > Using ?dput can help make it easier for others to recreate your object to > test code: > >> dput(W) > structure(c(651, 13.24184, 651, 13.24184, 651, 13.24184, 651, > 13.24184, 651, 13.24184, 651, 13.24184, 651, 13.24184, 119, 16.19418, > 78, 15.47089, 78, 15.47089), .Dim = c(2L, 10L)) > > > W <- structure(c(651, 13.24184, 651, 13.24184, 651, 13.24184, 651, > 13.24184, 651, 13.24184, 651, 13.24184, 651, 13.24184, 119, > 16.19418, > 78, 15.47089, 78, 15.47089), .Dim = c(2L, 10L)) > > > See ?which.max, which returns the index of the *first* maximum in the vector > passed to it: > >> W[1, which.max(W[2, ])] > [1] 119 > > > You should consider what happens if there is more than one of the maximum > value in the first row and if it might correspond to non-unique values in the > second row. Correction in the above sentence, it should be: You should consider what happens if there is more than one of the maximum value in the second row and if it might correspond to non-unique values in the first row. Marc ______________________________________________ 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.
