## zUnion ##### *Description* Creates an union of sorted sets given in second argument. The result of the union will be stored in the sorted set defined by the first argument. The third optionnel argument defines `<span class="calibre12">weights</span>` to apply to the sorted sets in input. In this case, the `<span class="calibre12">weights</span>` will be multiplied by the score of each element in the sorted set before applying the aggregation. The forth argument defines the `<span class="calibre12">AGGREGATE</span>`option which specify how the results of the union are aggregated. 對keys對應的numkeys個有序集合計算合集，并將結果存儲在destination中。在傳遞輸入keys之前必須提供輸入keys的個數和其它可選參數。在默認情況下，元素的結果score是包含該元素的所有有序集合中score的和。如果使用WEIGHTS選項，你可以對每一個有序集合指定一個操作因子。這意味著每一個有序集合中的每個元素的score在傳遞給聚合函數之前均會被乘以該因子。當WEIGHTS沒有指定時，操作因子默認為1。 使用AGGREGATE選項，你可以指定交集中的結果如何被聚合。該選項默認值為SUM，在這種情況下，一個元素的所有score值均會被相加。當選項被設置為MIN或MAX時，結果集合中將會包含一個元素的最大或者最小的score值。如果destination已經存在，那么它將會被重寫。 ##### *Parameters* *keyOutput* *arrayZSetKeys* *arrayWeights* *aggregateFunction* Either "SUM", "MIN", or "MAX": defines the behaviour to use on duplicate entries during the zUnion. ##### *Return value* *LONG* The number of values in the new sorted set. ##### *Example* ``` <pre class="calibre16">$redis->delete('k1'); $redis->delete('k2'); $redis->delete('k3'); $redis->delete('ko1'); $redis->delete('ko2'); $redis->delete('ko3'); $redis->zAdd('k1', 0, 'val0'); $redis->zAdd('k1', 1, 'val1'); $redis->zAdd('k2', 2, 'val2'); $redis->zAdd('k2', 3, 'val3'); $redis->zUnion('ko1', array('k1', 'k2')); /* 4, 'ko1' => array('val0', 'val1', 'val2', 'val3') */ /* Weighted zUnion */ $redis->zUnion('ko2', array('k1', 'k2'), array(1, 1)); /* 4, 'ko1' => array('val0', 'val1', 'val2', 'val3') */ $redis->zUnion('ko3', array('k1', 'k2'), array(5, 1)); /* 4, 'ko1' => array('val0', 'val2', 'val3', 'val1') */ ``` ##