MongoDB 按小时分组 [英] MongoDB group by hour

问题描述

我将推文保存到 mongo DB:

I save tweets to mongo DB:

 twit.stream('statuses/filter', {'track': ['animal']}, function(stream) {
    stream.on('data', function(data) {
        console.log(util.inspect(data));

        data.created_at = new Date(data.created_at);
        collectionAnimal.insert(data, function(err, docs) {});
    });
});

没关系.

MongoDB 中的推文时间格式为:2014-04-25 11:45:14 GMT (column created_at)现在我需要在几小时内创建组列 created_at.我想要结果:

The tweet time in MongoDB is in format: 2014-04-25 11:45:14 GMT (column created_at) Now I need group column created_at in hours. I would like to have the result:

小时 |每小时计算推文

hour | count tweets in hour

1 |28

2 |26

3 |32

4 |42

5 |36

...

我的失败尝试:

    $keys = array('created_at' => true);
    $initial = array('count' => 0);
    $reduce = "function(doc, prev) { prev.count += 1 }";

    $tweetsGroup = $this->collectionAnimal->group( $keys, $initial, $reduce );

但我无法按小时分组.

怎么做?

推荐答案

我可以告诉你如何直接在 mongo 控制台上使用聚合框架进行分组

I could tell you how you can group using aggregation framework directly on mongo console

db.tweets.aggregate(
 { "$project": {
      "y":{"$year":"$created_at"},
      "m":{"$month":"$created_at"},
      "d":{"$dayOfMonth":"$created_at"},
      "h":{"$hour":"$created_at"},
      "tweet":1 }
 },
 { "$group":{ 
       "_id": { "year":"$y","month":"$m","day":"$d","hour":"$h"},
       "total":{ "$sum": "$tweet"}
   }
 })

更多选项你可以看这里:http://docs.mongodb.org/manual/reference/operator/aggregation-date/

For more options you can look here: http://docs.mongodb.org/manual/reference/operator/aggregation-date/

您还需要从所使用的任何一种编程语言中找到合适的方式来使用聚合框架.

You will also need to find appropriate way of of using aggregation framework from whichever programming language you are using.

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