Returns the top k (largest) elements for each key from this RDD as defined by the specified implicit Ordering[T].
Returns the top k (largest) elements for each key from this RDD as defined by the specified implicit Ordering[T]. If the number of elements for a certain key is less than k, all of them will be returned.
k, the number of top elements to return
the implicit ordering for T
an RDD that contains the top k values for each key
:: DeveloperApi :: Machine learning specific Pair RDD functions.