在Scala中为列表中的每一行获取元组的第一项

Question

我希望在Scala中做到这一点，但没有任何效果。

from operator import itemgetter
rdd = sc.parallelize([(0, [(0,'a'), (1,'b'), (2,'c')]), (1, [(3,'x'), (5,'y'), (6,'z')])])
mapped = rdd.mapValues(lambda v: map(itemgetter(0), v))

输出

mapped.collect()
[(0, [0, 1, 2]), (1, [3, 5, 6])]

Answer 1

val rdd = sparkContext.parallelize(List(
(0, Array((0, "a"), (1, "b"), (2, "c"))),
(1, Array((3, "x"), (5, "y"), (6, "z")))
))
rdd
.mapValues(v => v.map(_._1))
.foreach(v=>println(v._1+"; "+v._2.toSeq.mkString(",") ))

输出:

0; 0,1,2
1; 3,5,6