listunion/3—determine the union of two lists
The listunion/3 operation determines the union of two lists. The syntax for this function is as follows:
$LIST=listunion($LIST1,$LIST2)
listunion/3 arguments
Argument | Mode | Type | Description |
|---|---|---|---|
$LIST1 | Input | LIST_OF ANY | Specifies the first list to be compared |
$LIST2 | Input | LIST_OF ANY | Specifies the second list to be compared with the first list |
$LIST | Output | LIST_OF ANY | Union of the two lists |
Use the listunion/3 operation to construct a new list $LIST, which is the union of lists $LIST1 and $LIST2. The union of $LIST1 and $LIST2 will include all the elements of the two lists. If there are elements duplicated between the two lists, the duplicated elements will be listed only once in $LIST. If there are elements duplicated within a single list, those elements will be duplicated in the resulting list.
Consider the following example. The union of these two list ($LIST1 and $LIST2)is shown in the figure 2.
$LIST2=[b,d,e,e]
The union of the previously two lists:
- $LIST contains two a characters because $LIST1 has two a characters.
- $LIST contains two e characters because $LIST2 has two e characters.
- $LIST contains only one b because there is one b in $LIST1 and one b in $LIST2.
listunion/3 example