On Tue, 12 Aug 2003, Bing Zhang wrote: > Hi All, > > I have a 8000*8000 matrix and I want to print out a file with the row name, > column name and the value for those point with values satisfying a condition. > I tried using a for loop, however, it took me forever to get the result. Is > there a fast way to do this? Thanks! >
> aa <- matrix(rnorm(1000000), 1000, 1000) > found <- which(aa > 4, arr.ind=TRUE) > cbind(found, aa[found]) (for your condition) should do it. My matrix is a bit smaller though, but it goes quite fast. If you need the row/col names, you'll want to make some other structure than the cbind (as a data frame with character columns). > Bing > > --------------------------------- > 1060 Commerce Park > Oak Ridge National Laboratory > P.O. Box 2008, MS 6480 > Oak Ridge, TN 37831-6480 > Phone: 865-241-0761 > Email: [EMAIL PROTECTED] > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > -- Roger Bivand Economic Geography Section, Department of Economics, Norwegian School of Economics and Business Administration, Breiviksveien 40, N-5045 Bergen, Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93 e-mail: [EMAIL PROTECTED] ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
