On Mon, 26 Jan 2004 [EMAIL PROTECTED] wrote: > > Hi all > > I want to conditionally operate on certain elements of a matrix, let me > explain it with a simple vector example > > > > z<- c(1, 2, 3) > > zz <- c(0,0,0) > > null <- (z > 2) & ( zz <- z) > > zz > [1] 1 2 3 > > why zz is not (0, 0, 3) ????? >
Break it down into bits: > z<- c(1, 2, 3) > (z > 2) [1] FALSE FALSE TRUE > ( zz <- z) [1] 1 2 3 > (z > 2) & ( zz <- z) [1] FALSE FALSE TRUE > TRUE & ( zz <- z) [1] TRUE TRUE TRUE > rep(TRUE,4) & ( zz <- z) [1] TRUE TRUE TRUE TRUE Warning message: longer object length is not a multiple of shorter object length in: rep(TRUE, 4) & (zz <- z) The first part is a logical vector, the second is the result of assigning z to zz, & of them isn't terribly meaningful? Try: > zz <- ifelse(z > 2, z, 0) > zz [1] 0 0 3 if that's what you want. > > the null <- assignment is to keep the console silent > > in the other hand, it curious that null has reasonable values > > > null > [1] FALSE FALSE TRUE > > Thanks in advance > > Ulisses > > Debian GNU/Linux: a dream come true > ----------------------------------------------------------------------------- > "Computers are useless. They can only give answers." Pablo Picasso > > Humans are slow, innaccurate, and brilliant. > Computers are fast, acurrate, and dumb. > Together they are unbeatable > > ---> Visita http://www.valux.org/ para saber acerca de la <--- > ---> Asociación Valenciana de Usuarios de Linux <--- > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > -- Roger Bivand Econonic Geography Section, Department of Economics, Norwegian School of Economics and Business Administration, Breiviksveien 40, N-5045 Bergen, Norway, voice: +47-55959355, fax: +47-55959393; [EMAIL PROTECTED] ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html