- reduce()与fold()方法是对同种元素类型数据的RDD进行聚合操作,即必须同构。其返回值返回一个同样类型的新元素。
@Test
def fold(): Unit ={
val source = sc.parallelize(Seq(1,2,3,4,5,6))
val fold = source.fold(0)((x,y) => x+y)
println(fold) //21 0+1+2+3+4+5+6
val reduce = source.reduce((x,y) => x+y)
println(reduce) // 21 1+2+3+4+5+6
}