R: merge two data frame with replacing the common rows and col : I have two data. frame (suppose a,b having a size of 3172*1323, 3067*21), I want to merge both of them however, 21 columns are common in both and 3067 rows also common in both.
I want to merge both data frame such that the common rows and common cols replaced and the final size will be 3172*1323 only
I tried merge ( a,b, by =0) but it's not going to help me to get the data which I am looking for that.
Please help me