docstr: Each intermediate merge task will produce outputs for a partition of P
  final reduce tasks. This helper function returns P based on the merge
  task index.
docstr_tok: ["Each","intermediate","merge","task","will","produce","outputs","for","a","partition","of","P","final","reduce","tasks",".","This","helper","function","returns","P","based","on","the","merge","task","index","."]
code: def get_num_reducers_per_merge_idx(self, merge_idx: int) -> int:
      """
      Each intermediate merge task will produce outputs for a partition of P
      final reduce tasks. This helper function returns P based on the merge
      task index.
      """
      assert merge_idx < self.num_merge_tasks_per_round
      partition_size = self.merge_partition_size
      if merge_idx < self._partitions_with_extra_task:
          partition_size += 1
      return partition_size
  
imports: import logging
  import math
  from typing import Any, Callable, Dict, List, Optional, Tuple, TypeVar, Union
  import ray
  from ray.data._internal.block_list import BlockList
  from ray.data._internal.execution.interfaces import TaskContext
  from ray.data._internal.progress_bar import ProgressBar
  from ray.data._internal.remote_fn import cached_remote_fn
  from ray.data._internal.shuffle import ShuffleOp
  from ray.data.block import Block, BlockAccessor, BlockExecStats, BlockMetadata
  from ray.data.context import DataContext
  from ray.types import ObjectRef
  from ray.util.scheduling_strategies import NodeAffinitySchedulingStrategy
label_desc: Use image node_id 2 for calling the _MergeTaskSchedule obj's underlying member method code with example usage: obj.get_num_reducers_per_merge_idx(merge_idx) and returns: partition_size