Spark：如何將RDD [（Long，Iterable [String]）]轉換爲RDD [（Long，String）]？

Question

如何轉換這種RDD [（長，可迭代[字符串]）]以...

(852403,Set(PT0000094043, PT0000097083, PT0000036162)) 
(357331,Set(PT0000068829, PT0000094042, PT0000066859)) 

RDD [（長，字符串）]這樣嗎？

(852403, PT0000094043) 
(852403, PT0000097083) 
(852403, PT0000036162) 
(357331, PT0000068829) 
(357331, PT0000094042) 
(357331, PT0000066859) 

Answer 1

嘗試flatMapValues：

rdd.flatMapValues(identity) 

或flatMap：

rdd.flatMap{ case (k, vs) => vs.map(v => (k, v)) }