Groovy: Get index of all occurences of sublist from arraylist
I am new to groovy and trying to find the indexes of all sublists in a list.
I am trying to use something like Collections.indexOfSubList like in java but it gives exception saying it applies on Lists and not ArrayLists.
So I am trying to define my own function. I am finding all the indices of all the elements in the smaller list existing in the longer list and then subtracting the indices of the result array. If it comes to 1 then I am considering that index to a sublist.
I know that I have the logic a little twisted. Can somebody guide with a better and efficient way of doing this.
Below is my code:
List list1 = [1,2,3,4,5,6,1,2,3]
List list2 = [1,2]
index1 = list1.findIndexValues {
it == list2[0];
}
index2 = list1.findIndexValues {
it == list2[1];
}
println index1
println index2
result = []
for (int i = 0; i < index1.size(); i++) {
result.add(index2[i]-index1[i]);
}
println result
Edit: no longer uses Collections due to new issue re: Elastic Search.
The following code traverses along the source list, creating a sublist. It checks the sublist to see if it starts with the target list. See the asserts below (e.g. the indexes are 0-based):
def listStartsWithSubList = { source, target ->
def result = false
if (source.size() >= target.size()) {
result = true
target.eachWithIndex { item, index ->
result = result && (item == source[index])
}
}
result
}
def indexOfSubLists = { source, target ->
def results = []
source.eachWithIndex { item, index ->
def tmpList = source[index..source.size()-1]
if (listStartsWithSubList(tmpList, target)) {
results << index
}
}
results
}
assert [1] == indexOfSubLists([1,2,3], [2,3])
assert [2] == indexOfSubLists([1,2,3], [3])
assert [] == indexOfSubLists([1,2,3], [4])
assert [0,6] == indexOfSubLists([1,2,3,4,5,6,1,2,3], [1,2])