The issue here is that the equivalent command array(1:5, c(6,6)) (to matrix(1:5,6,6)) gives no warning, and sweep uses array().
I am not sure either should: fractional recycling was normally allowed in S3 (S4 tightened up a bit). Perhaps someone who thinks sweep() should warn could contribute a tested patch? On Mon, 20 Jun 2005, Heather Turner wrote: > > > Dr H Turner > Research Assistant > Dept. of Statistics > The University of Warwick > Coventry > CV4 7AL > > Tel: 024 76575870 > >>>> Robin Hankin <[EMAIL PROTECTED]> 06/20/05 10:32am >>> > Hi > > > I had a hard-to-find bug in some of my code the other day, which I > eventually > traced to my misusing of sweep(). > > I would expect sweep() to give > me a warning if the elements don't recycle nicely, but > > X <- matrix(1:36,6,6) > sweep(X,1,1:5,"+") > [,1] [,2] [,3] [,4] [,5] [,6] > [1,] 2 9 16 23 30 32 > [2,] 4 11 18 25 27 34 > [3,] 6 13 20 22 29 36 > [4,] 8 15 17 24 31 38 > [5,] 10 12 19 26 33 40 > [6,] 7 14 21 28 35 37 > > gives no warning, even though (5,36)=1. > > Also, > > > sweep(X,1,c(1,1000),"+") > > and > > sweep(X,2,c(1,1000),"+") > > > behave as expected, But > > > sweep(X,1,1:5,"+") > > and > > sweep(X,2,1:5,"+") > > > > are identical! > > ...which is also expected since the matrix is square. Perhaps the > following will help you see why: >> matrix(1:5,6,6) > [,1] [,2] [,3] [,4] [,5] [,6] > [1,] 1 2 3 4 5 1 > [2,] 2 3 4 5 1 2 > [3,] 3 4 5 1 2 3 > [4,] 4 5 1 2 3 4 > [5,] 5 1 2 3 4 5 > [6,] 1 2 3 4 5 1 > Warning message: > data length [5] is not a sub-multiple or multiple of the number of rows > [6] in matrix >> matrix(1:5,6,6, byrow = TRUE) > [,1] [,2] [,3] [,4] [,5] [,6] > [1,] 1 2 3 4 5 1 > [2,] 2 3 4 5 1 2 > [3,] 3 4 5 1 2 3 > [4,] 4 5 1 2 3 4 > [5,] 5 1 2 3 4 5 > [6,] 1 2 3 4 5 1 > Warning message: > data length [5] is not a sub-multiple or multiple of the number of rows > [6] in matrix > i.e. recycling a vector of length 5 down the columns gives the same > result as recycling the same vector along the rows. > > I agree with your main point however, it would be useful if 'sweep' > would give a warning when the length of the vector of statistics to be > swept out was not a sub-multiple or multiple of the corresponding array > dimension. > > Heather > > ______________________________________________ > 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 > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ 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
