Or, possibly slightly simpler: ok <- (x %% 2) * (y %% 2) d[ok == 1, ]
Peter Ehlers Petr Pikal wrote: > Hi > > I coords was data frame you could use some arithmetic to get > selection criteria for both numbers odd. In case of matrix you need > to use coords[,1]*coords[,2] instead > > trunc((coords$x*coords$y)/2)!=((coords$x*coords$y)/2) > [1] TRUE FALSE TRUE FALSE FALSE FALSE TRUE FALSE TRUE > coords[trunc((coords$x*coords$y)/2)!=((coords$x*coords$y)/2),] > > HTH > Petr > > > > On 13 Apr 2006 at 16:33, zhijie zhang wrote: > > Date sent: Thu, 13 Apr 2006 16:33:52 +0800 > From: "zhijie zhang" <[EMAIL PROTECTED]> > To: [email protected] > Subject: [R] a question on subset a dataset > > >>Dear R-users, >> I generate a dataset "d", and want to get a subset from it. >>** >>*z<-rnorm(9) >>coords<-cbind(x=c(1,1,1,2,2,2,3,3,3),y=c(1,2,3,1,2,3,1,2,3)) >>d<-SpatialPointsDataFrame(coords, data.frame (z=z[1:9]))* >>The result*/dataset* is >> coordinates z >>1 (1, 1) 1.41173570 >>2 (1, 2) 0.18546503 >>3 (1, 3) -0.04369144 >>4 (2, 1) -0.21591338 >>5 (2, 2) 1.46377535 >>6 (2, 3) 0.22966664 >>7 (3, 1) 0.10762363 >>8 (3, 2) -1.37810256 >>9 (3, 3) - 0.96818288 >> Now I want oto get a subset with x(rows) and y(columns) being odd >> numbers , >>that is , i want the subset like the following: >> coordinates z >> (1, 1) 1.41173570 >> (1, 3) -0.04369144 >> (3, 1) 0.10762363 >> (3, 3) -0.96818288 >>I think that the steps maybe: >>1.decompose coords into the original x and y; >>2.select the odd numbers of x and y; >>3.combine the selected x and y into coordinates, including the >>corresponding z-values. This is the subset. >> Hope someone can solve it. I failed to get the subset. >> >> >>-- >>Kind Regards,Zhi Jie,Zhang ,PHDDepartment of EpidemiologySchool of >>Public HealthFudan UniversityTel:86-21-54237149 >> >> [[alternative HTML version deleted]] >> >>______________________________________________ >>[email protected] mailing list >>https://stat.ethz.ch/mailman/listinfo/r-help >>PLEASE do read the posting guide! >>http://www.R-project.org/posting-guide.html > > > Petr Pikal > [EMAIL PROTECTED] > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
