How to get a “-Infinity” result for $avg in an aggregate query?

For this, you can use aggregate(). Let us first create a collection with documents with a vlaue as -infinity −

> db.demo5.insertOne({ "_id" : 100, "seq" : 10, "Value" : -Infinity });
{ "acknowledged" : true, "insertedId" : 100 }
> db.demo5.insertOne({ "_id" : 101, "seq" : 10, "Value" : 50 });
{ "acknowledged" : true, "insertedId" : 101 }
> db.demo5.insertOne({ "_id" : 102, "seq" : 20, "Value" : 60 });
{ "acknowledged" : true, "insertedId" : 102 }
> db.demo5.insertOne({ "_id" : 103, "seq" : 20, "Value" : 50 });
{ "acknowledged" : true, "insertedId" : 103 }

Following is the query to display all documents from a collection with the help of find() method −

> db.demo5.find();

This will produce the following output &miuns;

{ "_id" : 100, "seq" : 10, "Value" : -Infinity }
{ "_id" : 101, "seq" : 10, "Value" : 50 }
{ "_id" : 102, "seq" : 20, "Value" : 60 }
{ "_id" : 103, "seq" : 20, "Value" : 50 }

Here is the query to get a “-Infinity” result for $avg in an aggregate query. On the basis of seq, we have found the average. This results in -Infinity −

> db.demo5.aggregate([{$group:{"_id":"$seq", "average" : {$avg : "$Value"}}}]);

This will produce the following output −

{ "_id" : 20, "average" : 55 }
{ "_id" : 10, "average" : -Infinity }