It isn't completely clear to me what the criterion is for selecting elements, but if you want to change 8 to 40, but aren't sure where 8 is (or 8s are), then the following will work:
x[x==8] <- 40
The trick here is to index the matrix as a vector (since matrices in R are vectors with a dim attribute).
More generally, there's a great deal of free information available about how to use R that can help you to answer questions like this, including manuals supplied with the R distribution and other material available from the R web site.
John
At 12:04 AM 2/9/2003 +0900, Mitsuo Igarashi wrote:
Hi All. I am quite a newbie to R. This is a next basic question.I have a matrix; > x <- matrix(1:10.,5) > x [,1] [,2] [1,] 1 6 [2,] 2 7 [3,] 3 8 [4,] 4 9 [5,] 5 10 I like to get a modified matrix as follows; [,1] [,2] [1,] 1 6 [2,] 2 7 [3,] 3 8 * 5 -> 40 [4,] 4 9 [5,] 5 10 The following expression does not work. if (x[x[,1]==3]) x[x[,1]==3],2]*5 How can I obtain a right expresion to get a modified matrix?
----------------------------------------------------- John Fox Department of Sociology McMaster University Hamilton, Ontario, Canada L8S 4M4 email: [EMAIL PROTECTED] phone: 905-525-9140x23604 web: www.socsci.mcmaster.ca/jfox ----------------------------------------------------- ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help
