Perhaps use tapply() to split by the survey unit and write a little identity function that returns only those rows you want, then patch them all back together with something like simplify2array().
Michael On Tue, Nov 1, 2011 at 1:16 PM, Aurelie Cosandey Godin <god...@dal.ca> wrote: > Dear list, > > After reading different mails, blogs, and tried a few different codes without > any success, I am asking your help! > I have the following data frame where each row represent a survey unit with > the following variables: > >> names(RV09) > [1] "record.t" "trip" "set" "month" "stratum" "NAFO" > [7] "unit.area" "time" "dur.set" "distance" "operation" "mean.d" > [13] "min.d" "max.d" "temp.d" "slat" "slong" "spp" > [19] "number" "weight" "elat" "elong" > > Each survey unit generates one set record, denoted by a 5 in column > "record.t". Each species identified in this particular survey unit generates > an additional set record, denoted by a 6. > >> unique(RV09$record.t) > [1] 5 6 > > Each survey unit are identified by a specific "trip" and "set" number, so if > there is a 5 record type with no associated 6 records, it means that no > species were observed in that survey unit. I would like to be able to select > all and only these survey units, which represent my zeros. > > So as an exemple, in this trip number 913, set 1, 3, and 4 would be part of > my "zeros" data.frame as they appear with no record.t 6, such that no species > were observed in this survey unit. > >> head(RV09) > record.t trip set month stratum NAFO unit.area time dur.set distance > 585 5 913 1 10 351 3O R31 1044 17 9 > 586 5 913 2 10 351 3O R31 1440 17 9 > 587 6 913 2 10 351 3O R31 1440 17 9 > 588 5 913 3 10 340 3O Q31 1800 18 9 > 589 5 913 4 10 340 3O Q32 2142 17 9 > > Any tips on how extract this "zero" data.frame in R? > Thank you very much in advance! > > Best, > ~Aurelie > > > Aurelie Cosandey-Godin > Ph.D. student, Department of Biology > Industrial Graduate Fellow, WWF-Canada > Dalhousie University | Email: god...@dal.ca > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.
