Off topic:Retrieving values specific to a column

Question

[Sathya]

How to retrieve values specific to a column in comparison to other columns.

Say , there is a matrix of a dimension 10*3

   a1 a1.1 a1.2
1   A   A1   A2
2   B   B1   B3
3   C   C1   C4
4   D   D1   D6
5   E    E    E
6   F    F    F
7   G    G    G
8   H    H    H
9   I    I    I
10  J    J    J

And, I would like to get values specific to column. values which are common in more than one column need to be removed.Some thing like this

   a1 a1.1 a1.2
1   A   A1   A2
2   B   B1   B3
3   C   C1   C4
4   D   D1   D6

Is there any function in R to retrieve values specific to a column in comparison to other column?