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[统计mongodb 中某个 key 对应的 value 的出现频数] 统计一个 mongodb 数据库的 collection 中，所有 documents 内，统计某个特定字段的不同值各自出现次数。 #mongodb #pymongo

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SShawn91
Last edited Jan 25, 2019
Created on Oct 18, 2018

This example shows how to count the frequency of distinct values for a specified field across all documents in a MongoDB collection. The code defines a Python function using PyMongo’s `aggregate` method with MongoDB aggregation pipelines. It handles both simple fields and fields containing arrays of subdocuments, where a subfield is specified. The function filters documents with `$match`, unwinds arrays with `$unwind`, groups by value with `$group`, and sorts results by count using `$sort`.

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