Aggregate Function

The aggregate function in SwartzDB is used to perform calculations on a list of numeric values. It works seamlessly with the filter function when extracting numeric data.

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How aggregate Works

The aggregate function supports several operations:

Operation	Description
SUM	Adds up all values.
MIN	Finds the smallest value.
MAX	Finds the largest value.
AVG	Computes the average.
COUNT	Counts the number of elements.

Example Usage:

$result = $sdb->aggregate([10, 20, 30], 'SUM');  
// Output: 60

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Using aggregate with filter

Since filter extracts specific fields, it can return a list of numeric values. This list can then be passed directly into aggregate for calculations.

Example: Sum of All Prices

$filteredPrices = $sdb->filter($data, ["price"]);
$totalPrice = $sdb->aggregate($filteredPrices, 'SUM');

• filter extracts only the "price" column.
• aggregate calculates the total sum.

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Example: Finding the Highest Score

$scores = $sdb->filter($data, ["score"]);
$maxScore = $sdb->aggregate($scores, 'MAX');

• filter retrieves all scores.
• aggregate finds the highest score.

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Example: Calculating the Average Age

$ages = $sdb->filter($data, ["age"]);
$averageAge = $sdb->aggregate($ages, 'AVG');

• filter extracts all ages.
• aggregate computes the average.

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Why Use aggregate with filter?

✅ Dynamic calculations – Works with extracted data without needing manual processing.
✅ Efficient – Processes only relevant values instead of looping through full datasets.
✅ Readable Code – Makes operations like sum, min, and average easy to implement.

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Conclusion

The combination of filter and aggregate provides a powerful way to process numerical data in SwartzDB. First, filter extracts a specific column, then aggregate performs calculations on the result.