包含列表的两个data.frame列的相交值

Question

I have a data.frame with 2 colums containing list of values:

    names.t.      l1      l2
  1       x1    1, 0 1, 2, 0
  2       x2 1, 2, 0    1, 0

I would like to add a column to this data.frame that would give me the intersect of l1 and l2 values (as per the intersect set function). No for loops would be nice :)

In the above case, the expected result would be:

  names.t.      l1      l2    inters
1       x1    1, 0 1, 2, 0    1,0
2       x2 1, 2, 0    1, 0    1,0

To reproduce, use code the code below to load the original data.frame in s:

s <- structure(list(names.t. = structure(1:2, .Label = c("x1", "x2"
), class = "factor"), l1 = structure(list(x1 = list("1", "0"), 
    x2 = c("1", "2", "0")), .Names = c("x1", "x2")), l2 = structure(list(
    x1 = list("1", "2", "0"), x2 = c("1", "0")), .Names = c("x1", 
"x2"))), .Names = c("names.t.", "l1", "l2"), row.names = c(NA, 
-2L), class = "data.frame")

Answer 1

You can use Map with interesect :

s$inters <- Map(intersect, s$l1, s$l2)

#   names.t.      l1      l2 inters
# 1       x1    1, 0 1, 2, 0   1, 0
# 2       x2 1, 2, 0    1, 0   1, 0