调用reduceByKey时,它会使用相同的键对所有值求和.有没有办法计算每个键的平均值？
// I calculate the sum like this and don't know how to calculate the avg
reduceByKey((x,y)=>(x+y)).collect
Array(((Type1,1),4.0), ((Type1,1),9.2), ((Type1,2),8), ((Type1,2),4.5), ((Type1,3),3.5),
((Type1,3),5.0), ((Type2,1),4.6), ((Type2,1),4), ((Type2,1),10), ((Type2,1),4.3))