How do I combine two data-frames based on two columns

Question

I know I can use the plyr and its friends to combine dataframes  and merge as well  but so far I don t know how to merge two dataframes with multiple columns based on 2 columns

User · Answer

Hope this helps   df1   data frame CustomerId c 1 10                Hobby   c rep  sing   4   rep  pingpong   3   rep  hiking   3                 Product c rep  Toaster  3  rep  Phone   2   rep  Radio  3   rep  Stereo   2     df2   data frame CustomerId c 2 4 6  8  10  State c rep  Alabama  2  rep  Ohio  1     rep  Cal   2                 like c  sing    hiking    pingpong    hiking    sing     df3   merge df1  df2  by x c  CustomerId    Hobby    by y c  CustomerId    like      Assuming df1 Hobby and df2 like mean the same thing

User · Answer

See the documentation on  merge  which states   By default the data frames are merged on the columns with names they both have    but separate specifications of the columns can be given by by x and by y    This clearly implies that merge will merge data frames based on more than one column  From the final example given in the documentation   x  lt - data frame k1 c NA NA 3 4 5   k2 c 1 NA NA 4 5   data 1 5  y  lt - data frame k1 c NA 2 NA 4 5   k2 c NA NA 3 4 5   data 1 5  merge x  y  by c  k1   k2      NA s match   This example was meant to demonstrate the use of incomparables  but it illustrates merging using multiple columns as well  You can also specify separate columns in each of x and y using by x and by y

User · Answer

You can also use the join command  dplyr    For example    new dataset  lt - dataset1   gt   right join dataset2  by c  column1   column2

[r] How do I combine two data-frames based on two columns?

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