Mongo average aggregation query with no group

Question

I am trying to get the average of a whole field using the aggregation framework in Mongo. However i can\'t seem to find any example that uses it without a group parameter. <

Answer 1

So if your data actually was numeric which is it not and your intention is to exclude the documents that have a "greater than zero" value then you include a $match statement in your aggregation pipeline in order to "filter" out these documents:

db.EvaluatedSentiments.aggregate([
    { "$match": {
        "bvc": { "$gt": 0 }
    }},
    { "$group": {
        "_id": null,
        "bvc": { "$avg": "$bvc" }
    }}
])