Hi, At the 1st step, you only assign a name for the 1st row. However, fred has 4 rows which mean you need to assign 4 rownames for these 4 rows.
At the 2nd step, you only "CHANGE" the 1st rowname from 1 to APPLE If I am wrong please correct me. Thanks -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of snubian Sent: Monday, March 02, 2009 4:59 PM To: r-help@r-project.org Subject: [R] Error setting rowname if rowname currently NULL Hi, My first post here and new to R so please bear with me (long time programmer though, helping a friend with some scripts). I've noticed a behaviour when using rownames() that I think is odd, wondering if I'm doing something wrong. To illustrate, say I create a very simple matrix (called fred): fred<-matrix(,4,2) It looks like this: [,1] [,2] [1,] NA NA [2,] NA NA [3,] NA NA [4,] NA NA If I now try and set a row name for one of the rows (say the first row) to "APPLE", by doing this: rownames(fred)[1] <- "APPLE" I get an error: Error in dimnames(x) <- dn : length of 'dimnames' [1] not equal to array extent However, I found that if I first set all the rownames to anything at all, by using say: rownames(fred) <- c(1:4) Which gives me: [,1] [,2] 1 NA NA 2 NA NA 3 NA NA 4 NA NA Then my desired command works, and thus: rownames(fred)[1] <- "APPLE" Gives me what I want: [,1] [,2] APPLE NA NA 2 NA NA 3 NA NA 4 NA NA So, what this says to me is that to set the row names INDIVIDUALLY, they first need to be set to something (anything!). For what I am doing, I need to set the row names one at a time, as I iterate through a loop. So I found that to do this I first had to set the rownames to some dummy values as above. Then it works fine. But this seems a little kludgy and unnecessary to me, and I am wondering what I am doing wrong. Have just started in R so fumbling my way through somewhat. Any suggestions would be appreciated, thanks! -- View this message in context: http://www.nabble.com/Error-setting-rowname-if-rowname-currently-NULL-tp2229 8797p22298797.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list 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.
