promptfoo--promptfoo/examples/eval-named-metrics

eval-named-metrics (Named Metrics Example)

This example demonstrates custom metric naming and derivation in promptfoo.

Setup

npx promptfoo@latest init --example eval-named-metrics
cd eval-named-metrics

Run

promptfoo eval

Features Demonstrated

1. Dynamic Metric Names: Using template variables like {{speechStyle}}Style in defaultTest.assert to apply different metric names per test case. This enables:

   • A single assertion definition that applies to all tests
   • Filtered results by the metric name that was dynamically generated

2. Static Metric Names: Hardcoded metric names like Tone, Consistency, and Length

3. Derived Metrics: Creating custom metrics based on formulas (e.g., DoubleConsistency = Consistency * 2)

Dynamic Metric Example

defaultTest:
  assert:
    - type: llm-rubric
      value: The response uses {{speechStyle}} speech patterns
      metric: '{{speechStyle}}Style'

tests:
  - vars:
      body: Ahoy there!
      speechStyle: pirate # Results in metric name "pirateStyle"

  - vars:
      body: Set sail!
      speechStyle: nautical # Results in metric name "nauticalStyle"

This allows you to maintain hundreds of test cases with a compact defaultTest configuration while still having unique, filterable metric names per test.