BoostMap - wuyichen24/boost GitHub Wiki
BoostMap is based on HashMap. But it provides you the different way to manipulate the entries in a map. It also provides you the traditional ReduceByKey() function with is the second stage of MapReduce algorithm.
Methods for BoostList
Merge the values for each key iteratively using an associative and commutative reduce function. This will also perform the merging locally on each mapper before sending results to a reducer, similarly to a “combiner” in MapReduce.
Return a new BoostMap by applying a function to all elements of this BoostMap. This function is similar to the map() function for BoostList, but the difference is each element is represented as BoostPair.