Unique column values on a combination of columns in R Dataframe

Question

Problem: I have a dataframe (df)

    Source  Source1  Target   Target.1 Target.2 Target.3
1   SDB1    SDB2     TDB1     TDB2     TDB2     TDB2
2   STB1    STB2     TTB1     TTB2     TTB2     TTB3
3   SCOL1   SCOL2    TCOL1    TCOL2    TCOL3    TCOL4

I want a resultant dataframe which would look like (What I want is to get Unique pairs from rows 1 and 2):

X1    X2
SDB1  STB1
SDB2  STB2
TDB1  TTB1
TDB2  TTB2,TTB3

What I tried

I was able to get this till now and not sure how to proceed from here:

!(duplicated(t(df[c(1,2),])))

[1]  TRUE  TRUE  TRUE FALSE  TRUE

Answer 1

We can subset first two rows of dataframe and do aggregate

df1 <- as.data.frame(t(df[1:2, ]), row.names = FALSE)
names(df1) <- paste0('X', 1:2)
aggregate(X2~X1, df1, function(x) toString(unique(x)))

#    X1         X2
#1 SDB1       STB1
#2 SDB2       STB2
#3 TDB1       TTB1
#4 TDB2 TTB2, TTB3

---

Using dplyr , we can do :

library(dplyr)

df %>%
 slice(1:2) %>%
 t %>%
 as.data.frame() %>%
 group_by(V1) %>%
 summarise(V2 = toString(unique(V2)))