How to get common values between two columns in R?

Question

Dataframe as an example:

df <- data.frame(x = c("A,B,C","A,D","B,C,E","C,E,G"),
                 y = c("A","D","A",NA),
                 MyAim = c("A","D","",""))

      x    y MyAim
1 A,B,C    A     A
2   A,D    D     D
3 B,C,E    A      
4 C,E,G <NA>      

I want to get common values between x and y columns in a new one. Thanks in advance.

Answer 1

We can use mapply :

df$Z <- mapply(function(x, y) {
            temp <- intersect(x, y)
            if(length(temp)) temp else ""
        }, strsplit(df$x, ","), df$y)

df
#      x    y Z
#1 A,B,C    A A
#2   A,D    D D
#3 B,C,E    A  
#4 C,E,G <NA>  

---

If there are multiple values in y, we can split the string in y and return a comma-separated value.

df$Z <- mapply(function(x, y) {
     temp <- intersect(x, y)
     if(length(temp)) toString(temp) else ""
     }, strsplit(df$x, ","), strsplit(df$y, ","))

data

df <- data.frame(x = c("A,B,C","A,D","B,C,E","C,E,G"),
                 y = c("A","D","A",NA),
                 stringsAsFactors = FALSE)