extend_unique

Adds a list or tuple with items to the end of a list, and returns the new length. Only items which do not have a duplicate in the list will be added.

An item in the list is marked as a duplicate when an item is compared as equal to another item using the == operator.

If the original list contains duplicate items, those items remain untouched. See example 2.

This function generates an event (except when called on a variable).

Function

list.extend_unique(list)

Arguments

Argument Type Description
list list/tuple The list or tuple to extend the list with.

Return value

Returns the new length of the list.

Example 1

This code extends a list with a given array:

a = [0, 1, 2];
b = range(6);
a.extend_unique(b);  // returns the new length, 6 (0, 1 and 2 are not added again)
a;

Return value in JSON format

[
    0,
    1,
    2,
    3,
    4,
    5
]

Example 2

Existing duplicates remain untouched:

list1 = ['A', 'A', 'B'];
list2 = ['B', 'B', 'C'];
list1.extend_unique(list2);

// Note that list2 is untouched and pre-existing duplicates
// in list1 are not removed
{
    list1: list1,
    list2: list2
};

Return value in JSON format

{
    "list1": [
        "A",
        "A",
        "B",
        "C"
    ],
    "list2": [
        "B",
        "B",
        "C"
    ]
}