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Alex Rivera
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If I understand correctly, by default data.table merges two tables by comparing columns which are set as keys and have same names. How should I write if I have tables with different column names? For example: set.seed(123) DT1<-data.table(col1=sample(letters,5,replace=TRUE),col2=sample(LETTERS[1:5],5,replace=TRUE),col3=sample(1:2,5,replace=TRUE)) DT2<-data.table(col4=sample(1:3,10,replace=TRUE),col5=sample(LETTERS[1:5],10,replace=TRUE),col6=sample(1:100,10,replace=TRUE)) (DT1) (DT2) > (DT1) col1 col2 col3 1: h A 2 2: u C 1 3: k E 2 4: w C 2 5: y C 1 > (DT2) col4 col5 col6 1: 3 D 48 2: 1 C 76 3: 1 C 22 4: 1 B 32 5: 3 A 24 6: 3 E 15 7: 3 E 42 8: 2 D 42 9: 3 D 37 10: 2 A 16 What should I write in DT1[ to make a merge selecting only rows with col2==col5 & col3==col4? Here is an expected output: col1 col2 col3 col4 col5 col6 h A 2 2 A 16 u C 1 1 C 76 u C 1 1 C 22 y C 1 1 C 76 y C 1 1 C 22 Thanks in advance!
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