Re: [R] Selecting rows/columns of a matrix
Hello, Try the following. a[as.logical(j), as.logical(j)] # or b - a[as.logical(j), ] t(b)[as.logical(j), ] Hope this helps, Rui Barradas Em 26-10-2014 18:35, Steven Yen escreveu: Dear I am interested in selecting rows and columns of a matrix with a criterion defined by a binary indicator vector. Let matrix a be a-matrix(1:16, 4,4,byrow=T) a [,1] [,2] [,3] [,4] [1,]1234 [2,]5678 [3,]9 10 11 12 [4,] 13 14 15 16 Elsewhere in Gauss, I select the first and third rows and columns of a by defining a column vector j = [1,0,1,0]. Then, select the rows of a using j, and then selecting the rows of the transpose of the resulting matrix using j again. I get the 2 x 2 matrix as desired. Is there a way to do this in R? below are my Gauss commands. Thank you. --- j 1 0 1 0 a=selif(a,j); a 1 2 3 4 9 10 11 12 a=selif(a',j); a 1 9 3 11 __ 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. __ 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.
Re: [R] Selecting rows/columns of a matrix
Sorry, that should be t(a[as.logical(j), as.logical(j)]) Rui Barradas Em 26-10-2014 18:45, Rui Barradas escreveu: Hello, Try the following. a[as.logical(j), as.logical(j)] # or b - a[as.logical(j), ] t(b)[as.logical(j), ] Hope this helps, Rui Barradas Em 26-10-2014 18:35, Steven Yen escreveu: Dear I am interested in selecting rows and columns of a matrix with a criterion defined by a binary indicator vector. Let matrix a be a-matrix(1:16, 4,4,byrow=T) a [,1] [,2] [,3] [,4] [1,]1234 [2,]5678 [3,]9 10 11 12 [4,] 13 14 15 16 Elsewhere in Gauss, I select the first and third rows and columns of a by defining a column vector j = [1,0,1,0]. Then, select the rows of a using j, and then selecting the rows of the transpose of the resulting matrix using j again. I get the 2 x 2 matrix as desired. Is there a way to do this in R? below are my Gauss commands. Thank you. --- j 1 0 1 0 a=selif(a,j); a 1 2 3 4 9 10 11 12 a=selif(a',j); a 1 9 3 11 __ 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. __ 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. __ 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.
Re: [R] Selecting rows/columns of a matrix
Rui Thanks. This works great. Below, I get the 2nd, 4th, and 6th rows/columns: (a-matrix(1:36,6,6)) [,1] [,2] [,3] [,4] [,5] [,6] [1,]17 13 19 25 31 [2,]28 14 20 26 32 [3,]39 15 21 27 33 [4,]4 10 16 22 28 34 [5,]5 11 17 23 29 35 [6,]6 12 18 24 30 36 (j-matrix(c(0,1,0,1,0,1))) [,1] [1,]0 [2,]1 [3,]0 [4,]1 [5,]0 [6,]1 ((a[as.logical(j), as.logical(j)])) [,1] [,2] [,3] [1,]8 20 32 [2,] 10 22 34 [3,] 12 24 36 Steven Yen At 02:49 PM 10/26/2014, Rui Barradas wrote: Sorry, that should be t(a[as.logical(j), as.logical(j)]) Rui Barradas Em 26-10-2014 18:45, Rui Barradas escreveu: Hello, Try the following. a[as.logical(j), as.logical(j)] # or b - a[as.logical(j), ] t(b)[as.logical(j), ] Hope this helps, Rui Barradas Em 26-10-2014 18:35, Steven Yen escreveu: Dear I am interested in selecting rows and columns of a matrix with a criterion defined by a binary indicator vector. Let matrix a be a-matrix(1:16, 4,4,byrow=T) a [,1] [,2] [,3] [,4] [1,]1234 [2,]5678 [3,]9 10 11 12 [4,] 13 14 15 16 Elsewhere in Gauss, I select the first and third rows and columns of a by defining a column vector j = [1,0,1,0]. Then, select the rows of a using j, and then selecting the rows of the transpose of the resulting matrix using j again. I get the 2 x 2 matrix as desired. Is there a way to do this in R? below are my Gauss commands. Thank you. --- j 1 0 1 0 a=selif(a,j); a 1 2 3 4 9 10 11 12 a=selif(a',j); a 1 9 3 11 __ 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. __ 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. __ 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.
Re: [R] Selecting rows/columns of a matrix
Use logical vectors and the [ operator: x[condition] can be read as 'x such that condition [is true]'. E.g., a-matrix(1:16, 4,4,byrow=T) j - c(TRUE, FALSE, TRUE, FALSE) a[j,,drop=FALSE] [,1] [,2] [,3] [,4] [1,]1234 [2,]9 10 11 12 a[,j,drop=FALSE] [,1] [,2] [1,]13 [2,]57 [3,]9 11 [4,] 13 15 a[j,j,drop=FALSE] # apply t() to the result if you want the transpose [,1] [,2] [1,]13 [2,]9 11 The drop=FALSE is not needed in these examples, but prevents single-row or -column results from be converted to vectors. See An Introduction to R (under HelpManuals in the Windows GUI, or look on the R website) for details on these and many other issues. Bill Dunlap TIBCO Software wdunlap tibco.com On Sun, Oct 26, 2014 at 11:35 AM, Steven Yen sye...@gmail.com wrote: Dear I am interested in selecting rows and columns of a matrix with a criterion defined by a binary indicator vector. Let matrix a be a-matrix(1:16, 4,4,byrow=T) a [,1] [,2] [,3] [,4] [1,]1234 [2,]5678 [3,]9 10 11 12 [4,] 13 14 15 16 Elsewhere in Gauss, I select the first and third rows and columns of a by defining a column vector j = [1,0,1,0]. Then, select the rows of a using j, and then selecting the rows of the transpose of the resulting matrix using j again. I get the 2 x 2 matrix as desired. Is there a way to do this in R? below are my Gauss commands. Thank you. --- j 1 0 1 0 a=selif(a,j); a 1 2 3 4 9 10 11 12 a=selif(a',j); a 1 9 3 11 __ 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. __ 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.
Re: [R] Selecting rows/columns of a matrix
Note that you do not have to create the vector of 1's (TRUE) and 0's (FALSE) if you know the index values: j - c(2, 4, 6) a[j, j] [,1] [,2] [,3] [1,]8 20 32 [2,] 10 22 34 [3,] 12 24 36 == David L. Carlson Department of Anthropology Texas AM University -Original Message- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Steven Yen Sent: Sunday, October 26, 2014 1:57 PM To: Rui Barradas; r-help Subject: Re: [R] Selecting rows/columns of a matrix Rui Thanks. This works great. Below, I get the 2nd, 4th, and 6th rows/columns: (a-matrix(1:36,6,6)) [,1] [,2] [,3] [,4] [,5] [,6] [1,]17 13 19 25 31 [2,]28 14 20 26 32 [3,]39 15 21 27 33 [4,]4 10 16 22 28 34 [5,]5 11 17 23 29 35 [6,]6 12 18 24 30 36 (j-matrix(c(0,1,0,1,0,1))) [,1] [1,]0 [2,]1 [3,]0 [4,]1 [5,]0 [6,]1 ((a[as.logical(j), as.logical(j)])) [,1] [,2] [,3] [1,]8 20 32 [2,] 10 22 34 [3,] 12 24 36 Steven Yen At 02:49 PM 10/26/2014, Rui Barradas wrote: Sorry, that should be t(a[as.logical(j), as.logical(j)]) Rui Barradas Em 26-10-2014 18:45, Rui Barradas escreveu: Hello, Try the following. a[as.logical(j), as.logical(j)] # or b - a[as.logical(j), ] t(b)[as.logical(j), ] Hope this helps, Rui Barradas Em 26-10-2014 18:35, Steven Yen escreveu: Dear I am interested in selecting rows and columns of a matrix with a criterion defined by a binary indicator vector. Let matrix a be a-matrix(1:16, 4,4,byrow=T) a [,1] [,2] [,3] [,4] [1,]1234 [2,]5678 [3,]9 10 11 12 [4,] 13 14 15 16 Elsewhere in Gauss, I select the first and third rows and columns of a by defining a column vector j = [1,0,1,0]. Then, select the rows of a using j, and then selecting the rows of the transpose of the resulting matrix using j again. I get the 2 x 2 matrix as desired. Is there a way to do this in R? below are my Gauss commands. Thank you. --- j 1 0 1 0 a=selif(a,j); a 1 2 3 4 9 10 11 12 a=selif(a',j); a 1 9 3 11 __ 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. __ 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. __ 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. __ 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.
