I want to remove part of the list where it is a complete set of the other part of the list. For example, B intersect A and E intersect C, therefore B and E should be removed.
MyList <- list(A=c(1,2,3,4,5), B=c(3,4,5), C=c(6,7,8,9), E=c(7,8))
MyList
$A
[1] 1 2 3 4 5
$B
[1] 3 4 5
$C
[1] 6 7 8 9
$E
[1] 7 8
MyListUnique <- RemoveSubElements(MyList)
MyListUnique
$A
[1] 1 2 3 4 5
$C
[1] 6 7 8 9
Any ideas ? Any know function to do it ?
As long as your data is not too huge, you can use an approach like the following:
# preparation
MyList <- MyList[order(lengths(MyList))]
idx <- vector("list", length(MyList))
# loop through list and compare with other (longer) list elements
for(i in seq_along(MyList)) {
idx[[i]] <- any(sapply(MyList[-seq_len(i)], function(x) all(MyList[[i]] %in% x)))
}
# subset the list
MyList[!unlist(idx)]
#$C
#[1] 6 7 8 9
#
#$A
#[1] 1 2 3 4 5
Similar to the other answer, but hopefully clearer, using a helper function and 2 sapplys.
#helper function to determine a proper subset - shortcuts to avoid setdiff calculation if they are equal
is.proper.subset <- function(x,y) !setequal(x,y) && length(setdiff(x,y))==0
#double loop over the list to find elements which are proper subsets of other elements
idx <- sapply(MyList, function(x) any(sapply(MyList, function(y) is.proper.subset(x,y))))
#filter out those that are proper subsets
MyList[!idx]
$A
[1] 1 2 3 4 5
$C
[1] 6 7 8 9
