Hello, I am having some problems to use the 'merge' function. I'm not sure if I got its working right.
What I want to do is: 1) Suppose I have a dataframe like: height width 1 1.1 2.3 2 2.1 2.5 3 1.8 1.9 4 1.6 2.1 5 1.8 2.4 2) And I generate a second dataframe sampled from this one, like: height width 1 1.1 2.3 3 1.8 1.9 5 1.8 2.4 3) Next, I add a new variable from this dataframe: height width color 1 1.1 2.3 red 3 1.8 1.9 red 5 1.8 2.4 blue 4) So, I want to merge those dataframes, so that the new variable, color, is binded to the first dataframe. Of course some cases won't have value for it, since I generated this variable in a smaller dataframe. In those cases I want the value to be NA. The result dataframe should be: height width color 1 1.1 2.3 red 2 2.1 2.5 NA 3 1.8 1.9 red 4 1.6 2.1 NA 5 1.8 2.4 blue I have written some codes, but they're not working properly. The new variable has its values mixed up, and they do not correspond to its row.names. # Generate the first dataframe data1 <- data.frame(height=rnorm(20,3,0.2),width=rnorm(20,2,0.5)) # Sample a smaller dataframe from data1 data2 <- data1[sample(1:20,15,replace=F),] # Generate the new variable color <- sample(c("red","blue"),15,replace=T) # Bind the new variable to data2 data2 <- cbind(data2, color) # Merge the data1 and data2$color by row.names, and force it to has the same values that data1. Next it generates a new dataframe where column 1 is the row.name, and then sort it by the row.name from data1. data.frame(merge(data1,data2$color, by=0, all.x=T),row.names=1)[row.names(data1),] I'm not sure what am I doing wrong. Can anyone see where the mistake is? Thank you! Cheers, Joao D. -- View this message in context: http://r.789695.n4.nabble.com/Merge-dataframes-tp3882222p3882222.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.