Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com
> -----Original Message----- > From: r-help-boun...@r-project.org > [mailto:r-help-boun...@r-project.org] On Behalf Of anna > Sent: Friday, January 29, 2010 2:46 PM > To: r-help@r-project.org > Subject: Re: [R] Simple question on replace a matrix row > > > What I did now is that I checked the class of both matrix > before assigning > the first row of mat2: > class(mainMat) --> "matrix" > class(mainMat[1,]) --> "list" > class(mat2) --> "matrix" > mat2[1,]<-mainMat[1,] > class(mat2) --> "list" > I think the problem comes from mainMat[1,] that should be of > class "matrix" > but is of class "list"... You need to look further into the structure of those objects to see what is going on. A matrix can contain data of any simple enough (vector-like) class, e.g., "numeric", "integer", "list", or "logical". The class of the matrix is always "matrix", no matter what is in it. A "matrix" can be subscripted with 2 subscripts and contains one vector of data, in column major order, of length nrow(matrix)*ncol(matrix). (A "data.frame" is another 2 dimensional object with a quite different structure and significantly different behavior.) I'd recommend using str() to get a fuller picture: > matList<-matrix(lapply(1:4,seq_len), 2, 2) > matNumeric<-matrix(exp(0:3), 2, 2) > class(matList) [1] "matrix" > class(matNumeric) [1] "matrix" > str(matList) List of 4 $ : int 1 $ : int [1:2] 1 2 $ : int [1:3] 1 2 3 $ : int [1:4] 1 2 3 4 - attr(*, "dim")= int [1:2] 2 2 > str(matNumeric) num [1:2, 1:2] 1 2.72 7.39 20.09 Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > Anna Lippel > -- > View this message in context: > http://n4.nabble.com/Simple-question-on-replace-a-matrix-row-t p1427857p1437234.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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.
