Apache spark 连接rdd列表中的元素

我的RDD如下所示

>>> rdd.collect()
[([u'steve'], [u'new', u'york'], [u'baseball']), ([u'smith'], [u'virginia'], [u'football'])]

如何获得新的RDD as

[([u'steve'], [u'newyork'], [u'baseball']), ([u'smith'], [u'virginia'], [u'football'])]

我尝试用JOIN将其映射到新的rdd，但它不起作用

我能够解决这个问题

>>> rdd2=rdd.map(lambda l: [''.join(x) for x in l])
>>> rdd2.map(tuple).collect()
[([u'steve'], [u'newyork'], [u'baseball']), ([u'smith'], [u'virginia'], [u'football'])]