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# AggregationOperation

The type of aggregation operation used to compute a summary statistic.

```
enum AggregationOperation
```

## Overview

Each case pairs a statistical function with the [`Metric`](/documentation/Evaluations/Metric) it operates on,
except [`AggregationOperation.custom(label:)`](/documentation/Evaluations/AggregationOperation/custom(label:)) which represents a custom computation.

## Topics

### Enumeration Cases

[`case custom(label: String)`](/documentation/Evaluations/AggregationOperation/custom(label:))

A custom aggregation identified by its label.

[`case maximum(of: Metric)`](/documentation/Evaluations/AggregationOperation/maximum(of:))

The maximum of the metric’s values.

[`case mean(of: Metric)`](/documentation/Evaluations/AggregationOperation/mean(of:))

The arithmetic mean of the metric’s values.

[`case median(of: Metric)`](/documentation/Evaluations/AggregationOperation/median(of:))

The median of the metric’s values.

[`case minimum(of: Metric)`](/documentation/Evaluations/AggregationOperation/minimum(of:))

The minimum of the metric’s values.

[`case mode(of: Metric)`](/documentation/Evaluations/AggregationOperation/mode(of:))

The mode of the metric’s values.

[`case standardDeviation(of: Metric)`](/documentation/Evaluations/AggregationOperation/standardDeviation(of:))

The standard deviation of the metric’s values.

[`case variance(of: Metric)`](/documentation/Evaluations/AggregationOperation/variance(of:))

The variance of the metric’s values.

### Instance Properties

[`var label: String`](/documentation/Evaluations/AggregationOperation/label)

The display label this operation produces.

### Default Implementations

[Decodable Implementations](/documentation/Evaluations/AggregationOperation/Decodable-Implementations)

[Encodable Implementations](/documentation/Evaluations/AggregationOperation/Encodable-Implementations)

## Relationships

### Conforms To

[`Decodable`](/documentation/Swift/Decodable)

[`Encodable`](/documentation/Swift/Encodable)

[`Equatable`](/documentation/Swift/Equatable)

[`Sendable`](/documentation/Swift/Sendable)

[`SendableMetatype`](/documentation/Swift/SendableMetatype)

[`Escapable`](/documentation/Swift/Escapable)

[`Copyable`](/documentation/Swift/Copyable)

---

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