Hi, Try ?merge() or ?join from library(plyr) If `dat1` and `dat2` are the datasets: res <- merge(dat1,dat2,by="Code",all=TRUE) res[is.na(res)] <- 0 res # Code Cap04 Cap08 #1 2 120 120 #2 6 75 0 #3 7 220 112 #4 9 0 190 #5 17 4 4 A.K. Hello, I need to combine two data sets into one. For example: Dataset1: Code Cap04 2 120 6 75 7 220 17 4 Dataset2: Code Cap08 2 120 7 112 9 190 17 4 I need the dataset to look like the following where it keeps every unique 'code' from both datasets and fills the blanks in both rows with 0: FinalDataSet: Code Cap04 Cap08 2 120 120 6 75 0 7 220 112 9 0 190 17 4 4 Can anyone help me with this please? Thank you very much! Johnson