Hi Ryan, You're getting this result because five of the rows in a.one.qtr are duplicates, as a results of sampling with replacement:
length(which(duplicated(a.one.qtr))) [1] 5 The relevant section of the documentation (see ?merge) reads "The rows in the two data frames that match on the specified columns are extracted, and joined together. *If there is more than one match, all possible matches contribute one row each*" (emphasis mine). Best, Ista On Mon, Feb 6, 2012 at 3:29 PM, RKinzer <ry...@nezperce.org> wrote: > Hello all, > > First I have done extensive searches on this forum and others and nothing > seems to work. So I decided to post thinking someone could point me to the > write post or give me some help. > > I have drawn a 100 samples from a fictitious population (N=1000), and then > randomly selected 25% of the 100 samples. I would like to now merge the > data.frame from the 100 samples with the data.frame for the 25 individuals > from the sample. When I do this with the following code I get duplicate > rows, when I should have at most is 100. > > x<-mapply(rnorm,1000,c(54,78,89),c(3.5,5.5,5.9)) #sets up 1000 random > numbers for age 3,4,5 > x.3<-sample(x[,1],60) #randomly selects 60 lengths from age 3 > x.4<-sample(x[,2],740) > x.5<-sample(x[,3],200) > length<-c(x.3,x.4,x.5) > length<-round(length,digits=0) #rounds lengths to whole number > age3<-rep(3,60) > age4<-rep(4,740) > age5<-rep(5,200) > age<-c(age3,age4,age5) #combines ages into one vector > unique<-1:1000 #gives each fish a unique id > pop<-data.frame(unique,length,age) > pop<-pop[sample(1:1000,size=1000,replace=FALSE),] #randomized the order of > pop > c.one<-pop[sample(1:1000,size=100,replace=TRUE),] > a.one.qtr<-c.one[sample(1:100,size=25,replace=TRUE),] > merge<-merge(c.one,a.one.qtr,by="unique",all=TRUE) > > What I would ultimately like to have is one row for all 100 in the sample > and three columns (unique, length, age). And then some way to identify the > 25 individual selected rows. > > Thank you upfront for any help. I have been stuck for days. > > Ryan > > > > -- > View this message in context: > http://r.789695.n4.nabble.com/Duplicate-rows-when-I-combine-two-data-frames-with-merge-tp4362685p4362685.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.
