Hi Doug, This is all pretty basic indexing stuff, maybe http://cran.r-project.org/doc/contrib/Short-refcard.pdf will get you started. Although... See below.
http://www.mail-archive.com/r-help@r-project.org/msg70906.html On Thu, Oct 15, 2009 at 1:17 PM, Douglas M. Hultstrand <dmhul...@metstat.com> wrote: > Hello, > > I have a couple questions about removing rows from a data frame and creating > a new data frame with the removed values. I provided an example data frame > (d) below. > > Questions: > 1) How can I search for "-999.000" and remove the entire row from data frame > "d"? (all -999 values will be in sd_diff) Usually I do something like d <- d[-which(d$sd_dif == -999.000),] but the discussion prompted by http://www.mail-archive.com/r-help@r-project.org/msg70906.html has made me a little nervous about this. Seems to work most of the time though, and I can't figure out how to do it with all.equal. > 2) Can I create a new data frame "d.new" that only contains the removed > rows? d.new <- d[which(d$sd_dif == -999.000),] will do the trick, with the same possible issues linked to above. Also make sure you do this before the previous step, otherwise d$sd_dif will not have any values equal to -999.000! > 3) How can I remove the last two rows from a data frame. (I used append > command to add two values to the end of the data) d <- d[ 1:(dim(d)[1]-2) , ] -Ista > >> d > lat.add lon.add PPT.add Z.add sd_dif > 1 37.67 -95.48 1.000 368 1.017 > 2 38.82 -92.22 13.208 383 5.737 > 3 37.30 -95.50 6.096 130 4.377 > 4 37.08 -95.57 0.508 106 -999.000 > 5 38.73 -93.55 6.350 370 6.233 > 6 38.83 -94.88 0.254 5 8.607 > 7 38.33 -96.18 0.508 43 8.665 > 8 38.85 -94.73 1.000 5 -999.000 > 9 38.71 -93.16 1.016 320 3.717 > 10 38.95 -95.67 1.000 5 8.553 > >> d.new > lat.add lon.add PPT.add Z.add sd_dif > 1 37.08 -95.57 0.508 106 -999.000 > 2 38.85 -94.73 1.000 5 -999.000 > > > Thanks for all the help, > Doug > > -- > --------------------------------- > Douglas M. Hultstrand, MS > Senior Hydrometeorologist > Metstat, Inc. Windsor, Colorado > voice: 970.686.1253 > email: dmhul...@metstat.com > web: http://www.metstat.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. > -- Ista Zahn Graduate student University of Rochester Department of Clinical and Social Psychology http://yourpsyche.org ______________________________________________ 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.
