$acos - Amazon DocumentDB
Example (MongoDB Shell)Code examples
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$acos

New from version 8.0.1.

The $acos operator in Amazon DocumentDB returns the arccosine (inverse cosine) of a value. The input value must be between -1 and 1.

Parameters

  • expression: An expression that resolves to a number between -1 and 1.

The result is in radians. To obtain degrees, apply $radiansToDegrees to the output.

The return type is double by default. If the input is a 128-bit decimal, the output is also a 128-bit decimal.

Example (MongoDB Shell)

The following example shows how to use the $acos operator to calculate the arccosine of numeric values.

Create sample documents

db.values.insertMany([
  { "_id": 1, "value": 1 },
  { "_id": 2, "value": 0 },
  { "_id": 3, "value": -1 }
]);

Query example

db.values.aggregate([
  { $project: {
    "angle": { $acos: "$value" }
  }}
]);

Output

[
  { "_id": 1, "angle": 0 },
  { "_id": 2, "angle": 1.5707963267948966 },
  { "_id": 3, "angle": 3.141592653589793 }
]

Code examples

To view a code example for using the $acos operator, choose the tab for the language that you want to use:

Node.js
const { MongoClient } = require('mongodb');

async function main() {
  const client = await MongoClient.connect('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false');
  const db = client.db('test');
  const collection = db.collection('values');

  const result = await collection.aggregate([
    { $project: {
      "angle": { $acos: "$value" }
    }}
  ]).toArray();

  console.log(result);
  await client.close();
}

main();
Python
from pymongo import MongoClient

def main():
    client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
    db = client['test']
    collection = db['values']

    result = list(collection.aggregate([
        { '$project': {
            'angle': { '$acos': '$value' }
        }}
    ]))

    print(result)
    client.close()

if __name__ == "__main__":
    main()