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$ln
New from version 4.0.
The $ln operator in Amazon DocumentDB calculates the natural logarithm (base e) of a specified number. It returns the logarithm of the number to the base e.
Parameters
Example (MongoDB Shell)
The following example demonstrates the usage of the $log operator to calculate the natural logarithm of a number.
Create sample documents
db.numbers.insertMany([
{ _id: 1, value: 10 },
{ _id: 2, value: 100 },
{ _id: 3, value: 1000 }
]);
Query example
db.numbers.aggregate([
{ $project: {
_id: 1,
naturalLog: { $ln: "$value" }
}}
]);
Output
[
{ "_id" : 1, "naturalLog" : 2.302585092994046 },
{ "_id" : 2, "naturalLog" : 4.605170185988092 },
{ "_id" : 3, "naturalLog" : 6.907755278982137 }
]
Code examples
To view a code example for using the $ln command, choose the tab for the language that you want to use:
- Node.js
-
const { MongoClient } = require('mongodb');
async function example() {
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('numbers');
const result = await collection.aggregate([
{ $project: {
_id: 1,
naturalLog: { $ln: "$value" }
}}
]).toArray();
console.log(result);
client.close();
}
example();
- Python
-
from pymongo import MongoClient
def example():
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.numbers
result = list(collection.aggregate([
{ "$project": {
"_id": 1,
"naturalLog": { "$ln": "$value" }
}}
]))
print(result)
client.close()
example()