PS ... actually, now I think about it... > as.polylist(apply(m, 1, polynom)) List of polynomials: [[1]] 1 + 5*x + 9*x^2 + 13*x^3
[[2]] 2 + 6*x + 10*x^2 + 14*x^3 [[3]] 3 + 7*x + 11*x^2 + 15*x^3 [[4]] 4 + 8*x + 12*x^2 + 16*x^3 This works with the PolynomF package because in that case the objects are functions and simplification is not possible. Another reason to leave polynomial behind and switch. Bill Venables. -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of bill.venab...@csiro.au Sent: Wednesday, 6 October 2010 2:07 PM To: macque...@llnl.gov; raznah...@mail.nih.gov; r-help@r-project.org Subject: [ExternalEmail] Re: [R] Using as.polynomial() over a matrix I was unaware of this discussion till now, so I'm not up with what's been said already. Here is how I would go about the problem I think you are trying to solve. > m <- matrix(1:16, 4, 4) > require(PolynomF) > (lop <- as.polylist(lapply(1:nrow(m), function(i) polynom(m[i,])))) List of polynomials: [[1]] 1 + 5*x + 9*x^2 + 13*x^3 [[2]] 2 + 6*x + 10*x^2 + 14*x^3 [[3]] 3 + 7*x + 11*x^2 + 15*x^3 [[4]] 4 + 8*x + 12*x^2 + 16*x^3 > plot(lop) # reasonably dull plot... > Note that the package PolynomF is intended to replace polynomial. The latter is just there for backward compatibility reasons. Bill Venables. -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of MacQueen, Don Sent: Wednesday, 6 October 2010 1:23 PM To: Raznahan, Armin (NIH/NIMH) [E]; r-help@r-project.org Subject: Re: [R] Using as.polynomial() over a matrix The key is in the help page for apply. It says (in part): In all cases the result is coerced by Œas.vector¹ to one of the basic vector types before the dimensions are set, so that (for example) factor results will be coerced to a character array. So although as.polynomial() returns an object of class polynomial, apply then runs as.vector() on it, which makes it not a polynomial class any more. You should also be running apply in the first index (1) not the second (2), as in apply( whatever, 1, function ) If you want it to apply the function to each row, which I think you do. The strange result you get is also explained by the help page: If each call to ŒFUN¹ returns a vector of length Œn¹, then Œapply¹ returns an array of dimension Œc(n, dim(X)[MARGIN])¹ if Œn > 1¹. This example will get you closer: > tmp <- matrix(1:12, ncol=3, byrow=TRUE) > foo <- apply(tmp,1, list) > lapply(foo,function(x) as.polynomial(unlist(x))) [[1]] 1 + 2*x + 3*x^2 [[2]] 4 + 5*x + 6*x^2 [[3]] 7 + 8*x + 9*x^2 [[4]] 10 + 11*x + 12*x^2 -Don On 10/4/10 6:10 PM, "Raznahan, Armin (NIH/NIMH) [E]" <raznah...@mail.nih.gov> wrote: > Hello All > > First - a warning. I'm not very R or programming savvy. > > I am trying to do something without much luck, and have scoured help-pages, > but nothing has come up. Here it is: > > I have a matrix (m) of approx 40,000 rows and 3 columns, filled with numbers. > > I would like to convert the contents of this matrix into another matrix (m_p), > where the numbers of (m) have been coerced into a polynomial - using a > function called "as.polynomial()" from the package (polynom). Each row of (m) > contains 3 terms to be made into a polynomial in the equivalent row of (m_p). > > I have tried a coupe of things: > > ------------------------------ > 1. Using apply() > > m_p<-apply(m, 2, as.polynomial) > > Here is what happens.. > >> dim(m) > [1] 40962 3 >> m_p<-apply(m, 2, as.polynomial) >> m_p[1:5,] > dM_I dM_a.c dM_a.c.sq > [1,] -0.00593058 -0.000688 3.65e-05 > [2,] -0.01913294 0.000103 1.41e-04 > [3,] -0.01317958 -0.001190 1.49e-04 > [4,] -0.02651112 -0.001550 2.37e-04 > [5,] -0.01680289 -0.003520 2.86e-04 > > So - looks like the coercion hasn't worked. BUT, if I do things piecemeal - it > looks ok.. > >> m_p1<-as.polynomial(m[1,]) >> m_p1 > -0.00593058 - 0.000688*x + 3.65e-05*x^2 > -------------------------------- > ------------------------------- > 2. This made me think I was making some wrong assumptions using apply(). So I > wrote a function "test()", to take each row of (m) , use as.polynomial() on > it, and stick the results into a new matrix, which it would then return.. > > test<-function(x){ > a<-nrow(x) > b<-ncol(x) > c<-matrix(0, a, b) > for (i in 1:a) { > c[i,]<-as.polynomial(x[i,]) } > return (c) > } > >> m_p<-test(m) >> dim(m_p) > [1] 40962 3 >> m_p[1:5,] > [,1] [,2] [,3] > [1,] -0.00593058 -0.000688 3.65e-05 > [2,] -0.01913294 0.000103 1.41e-04 > [3,] -0.01317958 -0.001190 1.49e-04 > [4,] -0.02651112 -0.001550 2.37e-04 > [5,] -0.01680289 -0.003520 2.86e-04 > > ------------------- > > I don't know why I can do what I want when taking each line at a time, but not > when trying to run through the whole matrix. > > Sorry if missing something obvious. Any help/pointers would be very > gratefully received > > Thanks v much > > Armin > > ______________________________________________ > R-help@r-project.org mailing list > https://BLOCKEDstat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://BLOCKEDwww.BLOCKEDR-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.
