> On Jul 3, 2015, at 9:33 AM, Zander, Joscha <joscha.zan...@roche.com> wrote: > > Good day R-community, > > i just wondered if it is a bug or a feature... > > When i have a matrix "mat" with one column and i delete the last row with > > mat <- mat[-nrow(mat),] the result is a list. > > So my next call mat[10,] will throw an "wrong dimension" error. > The proper call must be: > > mat <- as.matrix(mat[-nrow(mat),]) > > So is this desired behavior or a bug? > > I use R-version 2.15.3, but reconstructed this behavior in 3.2.0 as well. > > greetings > > -- > *Joscha Zander*
See: http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-do-my-matrices-lose-dimensions_003f mat <- matrix(1:12, ncol = 1) > str(mat) int [1:12, 1] 1 2 3 4 5 6 7 8 9 10 ... > mat[-nrow(mat), ] [1] 1 2 3 4 5 6 7 8 9 10 11 # This is a vector, not a list > str(mat[-nrow(mat), ]) int [1:11] 1 2 3 4 5 6 7 8 9 10 … > mat[-nrow(mat), , drop = FALSE] [,1] [1,] 1 [2,] 2 [3,] 3 [4,] 4 [5,] 5 [6,] 6 [7,] 7 [8,] 8 [9,] 9 [10,] 10 [11,] 11 # This is a matrix > str(mat[-nrow(mat), , drop = FALSE]) int [1:11, 1] 1 2 3 4 5 6 7 8 9 10 … Regards, Marc Schwartz P.S. are you restricted in being able to upgrade from a version of R that is two years old? ______________________________________________ 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.
