replacing values in a column with another column R

Question

I have two tables in different dimensions, now I want to replace value datA$swl1 with values in datB$swl2 according to userids.

datA

 id swl1
 1            


        

Answer 1

You can obtain this result with one line of code:

datA$swl1[datA$id %in% datB$id] <- datB$swl2
#> datA
#  id swl1
#1  1  0.8
#2  2  0.7
#3  3  0.6
#4  4  0.7
#5  5  0.7

With the %in% operator we select the entries of the column datA$swl1 that belong to rows with the same id as those listed in datB. These values in the column of datA$swl1 are then replaced with the entries of the swl2 column of datB.