Hi r-help-boun...@r-project.org napsal dne 04.05.2010 09:50:28:
> > Dear all, > > In my dataset I have 12 columns and 5824 rows. The second column contains > information about the height of a claim: it might be zero or positive. I > would like to do an analysis on the positive part of this matrix, but I do > need the other colums with this. So if there are like 1000 rows where the > second column is positive, I would like to extract this 1000x13 matrix into > another matrix. > > The beginning of my code is: > > Cars <- read.csv(filename, header=TRUE, row.names=NULL, sep=";") > attach(Cars) Do not do that. you will have troubles with referencing objects and changing them, unless you perfectly know which object you modify/reference. > n <- as.numeric(n) > s <- as.numeric(s) you either have n and s as numeric than there is no need for as.numeric or they come aout as factors and in that case you get numerical ***representation*** of levels, which is probably not what you want. > # et cetera, the other variabeles are declared as numeric or as factors > > # I've tried to extract the data the following way: > Cars2 <- Cars[Cars$s!=0] see ?"[" and matrix/data.frame indexing Cars2 <- Cars[Cars$s!=0, ] > > #However, then I get the error message: > Error in `[.data.frame`(Cars, Cars$s != 0) : undefined columns selected > > # If I try > s[s!=0] > # I do get the positive s-values, but how can I get all colums in a matrix? Cars is ***not*** matrix but data.frame. Seems to be minor difference but it is like mountain bike and racing bike. They look similar but their use and properties are quite different. Regards Petr > > Does anyone know how this can be done? Your help would be greatly > appreciated. > > Regards, > > Frank van Berkum > > > > -- > View this message in context: http://r.789695.n4.nabble.com/Extract-rows-with- > non-zero-elements-tp2125128p2125128.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. ______________________________________________ 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.
