需要帮助在pig拉丁语中丢弃完全外部联接结果中的空值。以下是两个数据集：
答：

(BOS,2)
(BUR,81)
(LAS,8)

第二：

(BUR,56)
(EWR,2)
(LAS,88)

完全外接后：c：

(BOS,2,,)
(BUR,81,BUR,56)
(,,EWR,2)
(LAS,8,LAS,88)

我需要得到以下格式的输出：

(BOS,2)
(BUR,137)
(EWR,2)
(LAS,96)

尝试了不同的组合，分组，扁平，袋状。。。但没能找到解决办法。非常感谢你的帮助。

airline = load '/demo/data/airline/airline.csv' using PigStorage(',') as (Origin: chararray, Dest: chararray); 
traffic_in = GROUP airline by Origin; 
traffic_in_count= FOREACH traffic_in generate group as Origin , COUNT(airline) as count ; 
traffic_out = GROUP airline by Dest; 
traffic_out_count = FOREACH traffic_out generate group as Dest ,COUNT (airline) as count; 
traffic_top = JOIN traffic_in_count by Origin FULL OUTER , traffic_out_count by Dest ;