The third argument, rereduce, has to do with whether or not this reduce function is operating on aggregate information or the raw results from the map (the ones from the map function).

第三个参数是 rereduce，这个参数必须处理这个 reduce 函数是在汇总信息上操作还是在来自映射的原始结果（来自 map 函数的结果）上操作。

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You can find all the Mappiness data in aggregate here including a happiness index chart, and a photo-map of the happiest locations in the UK, as well as real-time happiness meters.

你可以在这里找到所有Mappiness的数据，包括检索图、英国最幸福的地点的照片地图和即时的幸福程度。

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