Multiprocessor System-on-Chip (MPSoC) based on Network-on-Chip (NoC) integrates a large amount of Processor Elements (PEs) to fulfill the performance requirements of several applications. These applications are composed of a set of intercommunicating tasks, which are dynamically mapped onto PEs of the target architecture. However, the efficient task-mapping requires some previous steps, among them partitioning, which organizes tasks considering their interaction before applying a mapping process. This paper introduces Partition Reduce (PR) - a task partitioning approach based on the MapReduce algorithm targeting homogeneous NoC based MPSoCs. We analyze the efficiency of PR for energy consumption (EC) minimization and load balance (LB). The results obtained from a set of experiments, with large number of tasks, demonstrate that PR is more effective on processing time and result quality when compared to the classic Simulated Annealing (SA). In addition, PR produces partitions with low energy consumption and rigorous load balance.