Calculate pairwise Jaccard Indices between each pair of items in a list

pairwiseJaccardIndex(list)

pairwiseJaccardDistance(list)

Arguments

list: A list

Value

A symmetric matrix of dimension mxm, where m is the length of the list

pairwiseJaccardDistance is defined as 1-pairwiseJaccardIndex.

Examples


myList <- list(first=LETTERS[3:5], second=LETTERS[1:3], third=LETTERS[1:5], fourth=LETTERS[6:10])
pairwiseJaccardIndex(myList)
#>        first second third fourth
#> first    1.0    0.2   0.6      0
#> second   0.2    1.0   0.6      0
#> third    0.6    0.6   1.0      0
#> fourth   0.0    0.0   0.0      1

poormanPJI <- function(list) {
  sapply(list, function(x) sapply(list, function(y) jaccardIndex(x,y)))
}
stopifnot(identical(pairwiseJaccardIndex(myList), poormanPJI(myList)))