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Example 05
beginner
05
DataFrame
GroupBy
Aggregation

DataFrame GroupBy & Aggregation

GroupBy is one of the most powerful DataFrame operations. This example demonstrates splitting a dataset into groups based on a column value, then applying aggregate functions (mean, sum, count, min, max) to each group independently.

Deepbox Modules Used

deepbox/dataframe

What You Will Learn

  • Group rows by column values with .groupBy()
  • Apply aggregate functions: mean, sum, count, min, max
  • The result is a new DataFrame with one row per group
  • Equivalent to SQL GROUP BY ... agg()

Source Code

05-dataframe-groupby/index.ts
1import { DataFrame } from "deepbox/dataframe";23console.log("=== DataFrame GroupBy & Aggregation ===\n");45// Create sample sales data6const sales = new DataFrame({7  product: ["Laptop", "Mouse", "Laptop", "Keyboard", "Mouse", "Laptop", "Keyboard", "Mouse"],8  region: ["North", "North", "South", "North", "South", "North", "South", "South"],9  quantity: [5, 20, 3, 15, 25, 4, 10, 30],10  revenue: [5000, 400, 3000, 450, 500, 4000, 300, 600],11});1213// Display the raw data14console.log("Sales Data:");15console.log(`${sales.toString()}\n`);1617// Group by a single column and aggregate18console.log("\nGroup by single column");19// Group by product and calculate total sales20const byProduct = sales.groupBy("product");21const productStats = byProduct.agg({22  quantity: "sum",23  revenue: "sum",24});2526console.log("Sales by Product:");27console.log(`${productStats.toString()}\n`);2829// Group by region30// Calculate average sales by region31const byRegion = sales.groupBy("region");32const regionStats = byRegion.agg({33  quantity: "mean",34  revenue: "mean",35});3637console.log("Average Sales by Region:");38console.log(`${regionStats.toString()}\n`);3940// Perform multiple aggregations at once41console.log("\nMultiple aggregations");42// Calculate sum, mean, and count for each product43const detailedStats = byProduct.agg({44  quantity: "sum",45  revenue: "mean",46});4748console.log("Detailed Product Statistics:");49console.log(`${detailedStats.toString()}\n`);5051console.log("✓ GroupBy operations complete!");

Console Output

$ npx tsx 05-dataframe-groupby/index.ts
=== DataFrame GroupBy & Aggregation ===

Sales Data:
    product  region  quantity  revenue
0    Laptop   North         5     5000
1     Mouse   North        20      400
2    Laptop   South         3     3000
3  Keyboard   North        15      450
4     Mouse   South        25      500
5    Laptop   North         4     4000
6  Keyboard   South        10      300
7     Mouse   South        30      600


Group by single column
Sales by Product:
    product  quantity  revenue
0    Laptop        12    12000
1     Mouse        75     1500
2  Keyboard        25      750

Average Sales by Region:
   region  quantity  revenue
0   North        11   2462.5
1   South        17     1100


Multiple aggregations
Detailed Product Statistics:
    product  quantity  revenue
0    Laptop        12     4000
1     Mouse        75      500
2  Keyboard        25      375

✓ GroupBy operations complete!
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