From: Gabor Grothendieck <ggrothendieck_at_gmail.com>

Date: Fri 28 Jul 2006 - 00:38:22 EST

R-help@stat.math.ethz.ch 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. Received on Fri Jul 28 01:09:04 2006

Date: Fri 28 Jul 2006 - 00:38:22 EST

Use the notation x[ , 1, drop = FALSE]

See ?"["

On 7/27/06, Neuro LeSuperHéros <neuro3000@hotmail.com> wrote:

> Transpose vector extracted from a matrix

*>
**> Hello,
**>
**> I am doing a recursive analysis that uses every line (vector) of a matrix in
**> a loop. In the model, I need to transpose those vectors that are extracted
**> from a matrix.
**>
**> Using simple vectors (no matrix involved) the transpose function works fine:
**>
**> simplevector <-matrix(1:3,3,1)
**> tsimplevector <-t(simplevector) #transposed
**> dim(simplevector) #3x1 matrix (vector)
**> dim(tsimplevector)#1x3
**>
**> PROBLEM: However, when the vector is extracted from a matrix, its dimension
**> is NULL. In this case the transposed dimension is correct, but you'll see
**> the next example, that if a row was extracted, the dimension would be wrong:
**>
**> initialmatrix <- matrix(1:9,3,3)
**> extractedvector <-initialmatrix[,1] # extract first columm as vector
**> textractedvector <-t(extractedvector)#transposed
**> dim(extractedvector) #NULL!!!! <- not working
**> dim(textractedvector)#1x3 as expected
**>
**> I have tried to transform the extracted vector as.vector and as.matrix.
**> as.vector does not give the what I want (still NULL) and as.matrix can't
**> specify the number of row and columns so both vectors are vertical.
**>
**> In this example, I extract a column and a row. Notice that both
**> as.matrix(vector) have the same dimension. Notice that both transposed
**> vectors have 1x3 dimensions.
**>
**> initialmatrix <- matrix(1:9,3,3)
**> extractedvector3x1 <-initialmatrix[,1] # extract first columm as vector
**> extractedvector1x3 <-initialmatrix[1,] # extract first row as vector
**>
**> #Both are NULL
**> dim(extractedvector3x1) #NULL!!!!
**> dim(extractedvector1x3) #NULL!!!!
**>
**> #transposed dimensions both 1x3
**> dim(t(extractedvector3x1)) #1x3
**> dim(t(extractedvector1x3)) #1x3 <- not 3x1
**>
**> #as.vector: still NULL
**> dim(as.vector(extractedvector3x1)) #NULL!!!!
**> dim(as.vector(extractedvector1x3)) #NULL!!!!
**>
**> #as.matrix: Both dim at 3x1
**> dim(as.matrix(extractedvector3x1)) #3x1
**> dim(as.matrix(extractedvector1x3)) #3x1 <- Problem: not 1x3
**>
**> #as.matrix transposed: Both dim at 1x3
**> dim(as.matrix(t(extractedvector3x1))) #1x3
**> dim(as.matrix(t(extractedvector1x3))) #1x3 <- Problem: not 3x1
**>
**> How can I get correct dimensions? Is there a way to specify dimensions in
**> as.matrix?
**>
**> Neuro
**>
**> ______________________________________________
**> R-help@stat.math.ethz.ch 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@stat.math.ethz.ch 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. Received on Fri Jul 28 01:09:04 2006

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