See the help page for the "[" operator ... ?"[" ... and use the drop parameter as in: A[1,,drop=FALSE]
[,1] [,2] [,3] [,4] a1 1 4 7 10 B. On Mar 21, 2015, at 8:10 AM, J Robertson-Burns <robertsonbu...@btinternet.com> wrote: > This is Circle 8.1.44 of 'The R Inferno'. > > http://www.burns-stat.com/documents/books/the-r-inferno/ > > Pat > > On 21/03/2015 11:04, jean.cour...@math.u-psud.fr wrote: >> My question must be a trivial one. >> >> There is automatic coercicion to vector when extracting only one line of a >> matrix. >> # example >> A = matrix(1:12,3,4) >> rownames(A) = c('a1','a2','a3') >> >> i = 1:2 >> A[i,] >> # [,1] [,2] [,3] [,4] >> # a1 1 4 7 10 matrix >> # a2 2 5 8 11 >> >> i = 1 >> A[i,] >> # [1] 1 4 7 10 vector !!! >> >> # to get the rowname, it is necessary to do >> rownames(A)[i] >> # [1] "a1" >> >> Is it possible to get a (1,4)-matrix (without testing length(i) ) ? I see >> nothing in options()... >> >> Jean Coursol >> >> ______________________________________________ >> 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. ______________________________________________ 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.
