On Sat, Apr 17, 2010 at 7:25 PM, <mau...@alice.it> wrote: > After some headache with debugging my script, I finally isolated the problem > taht I am going to illustrate in the following example. > I expected matrix nrow to decrease consistently till 1. Instead, when the > matrix is left with one row only, its nrow jumps to 2 because the matrix > gets transposed. How come ?
Because the one-row matrix gets reduced to a vector: > B <- matrix(1:4, nrow = 2, byrow = TRUE) > class(B) [1] "matrix" > B1 <- B[-1,] > class(B1) [1] "integer" and as.matrix applied to a vector produces a one-column matrix (see ?as.matrix). > Thank you, > Maura > >> B <- c(1,2) >> B <- rbind(B,c(3,4)) >> B <- rbind(B,c(5,6)) >> B > [,1] [,2] > B 1 2 > 3 4 > 5 6 >> dim(B) > [1] 3 2 >> nrow(B) > [1] 3 >> >> #REMOVE ROW-1 OUT OF 3 >> B <- as.matrix(B[-1,]) >> B > [,1] [,2] > 3 4 > 5 6 >> dim(B) > [1] 2 2 >> nrow(B) > [1] 2 >> >> #REMOVE ROW-2 OUT OF 3 >> B <- as.matrix(B[-1,]) >> B > [,1] > [1,] 5 > [2,] 6 >> dim(B) > [1] 2 1 >> nrow(B) > [1] 2 > > > > tutti i telefonini TIM! > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. > -- Ista Zahn Graduate student University of Rochester Department of Clinical and Social Psychology http://yourpsyche.org ______________________________________________ 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.