MongoDB $log10 Operator

The $log10 operator in MongoDB is used to calculate the logarithm base 10 of a numeric expression. It is commonly utilized within the $project stage of an aggregation pipeline to perform mathematical logarithmic operations on field values. This guide will cover the syntax, examples, output, explanations, use cases, important points, and a summary of using the $log10 operator in MongoDB aggregation.

Syntax

{ $log10: <expression> }

• <expression>: A numeric expression or field reference for which to calculate the logarithm base 10.

Example

Consider a collection named statistics with documents containing revenue and expenses fields. We want to calculate the logarithm base 10 of the profit (revenue minus expenses) during an aggregation.

db.statistics.aggregate([
  {
    $project: {
      date: 1,
      profit_log10: { $log10: { $subtract: ["$revenue", "$expenses"] } }
    }
  }
]);

Output

The output will display documents with the date and calculated profit_log10 fields.

[
  { "_id": ObjectId("..."), "date": ISODate("2023-01-01"), "profit_log10": 3.0 },
  { "_id": ObjectId("..."), "date": ISODate("2023-01-02"), "profit_log10": 2.5 },
  // ... other documents
]

Explanation

• The $log10 operator is used within the $project stage to calculate the logarithm base 10 of the profit (result of subtracting expenses from revenue) for each document.
• The result is included in the output as the profit_log10 field.

Use

The $log10 operator in MongoDB is used for:

• Calculating the logarithm base 10 of numeric values in aggregation pipelines.
• Performing mathematical operations on fields within the $project stage.
• Analyzing and transforming data that involves logarithmic scales.

Important Points

• The $log10 operator takes a single expression as its argument.
• It is commonly used in conjunction with other arithmetic or logarithmic operators within aggregation pipelines.
• Ensure that the expressions provided result in valid numeric values.

Summary

The $log10 operator in MongoDB provides a way to calculate the logarithm base 10 of numeric expressions within aggregation pipelines. It is useful for scenarios where data analysis involves logarithmic scales or when transforming data to a different scale is required. Understanding how to use the $log10 operator is valuable for MongoDB developers working with aggregation pipelines to analyze and derive insights from data.