Context Precision
This example demonstrates how to use Mastra’s Context Precision metric to evaluate how precisely responses use provided context information.
Overview
The example shows how to:
- Configure the Context Precision metric
- Evaluate context precision
- Analyze precision scores
- Handle different precision levels
Setup
Environment Setup
Make sure to set up your environment variables:
.env
OPENAI_API_KEY=your_api_key_here
Dependencies
Import the necessary dependencies:
src/index.ts
import { openai } from '@ai-sdk/openai';
import { ContextPrecisionMetric } from '@mastra/evals/llm';
Example Usage
High Precision Example
Evaluate a response where all context is relevant:
src/index.ts
const context1 = [
'Photosynthesis converts sunlight into energy.',
'Plants use chlorophyll for photosynthesis.',
'Photosynthesis produces oxygen as a byproduct.',
'The process requires sunlight and chlorophyll.',
];
const metric1 = new ContextPrecisionMetric(openai('gpt-4o-mini'), {
context: context1,
});
const query1 = 'What is photosynthesis and how does it work?';
const response1 = 'Photosynthesis is a process where plants convert sunlight into energy using chlorophyll, producing oxygen as a byproduct.';
console.log('Example 1 - High Precision:');
console.log('Context:', context1);
console.log('Query:', query1);
console.log('Response:', response1);
const result1 = await metric1.measure(query1, response1);
console.log('Metric Result:', {
score: result1.score,
reason: result1.info.reason,
});
// Example Output:
// Metric Result: { score: 1, reason: 'The context uses all relevant information and does not include any irrelevant information.' }
Mixed Precision Example
Evaluate a response where some context is irrelevant:
src/index.ts
const context2 = [
'Volcanoes are openings in the Earth\'s crust.',
'Volcanoes can be active, dormant, or extinct.',
'Hawaii has many active volcanoes.',
'The Pacific Ring of Fire has many volcanoes.',
];
const metric2 = new ContextPrecisionMetric(openai('gpt-4o-mini'), {
context: context2,
});
const query2 = 'What are the different types of volcanoes?';
const response2 = 'Volcanoes can be classified as active, dormant, or extinct based on their activity status.';
console.log('Example 2 - Mixed Precision:');
console.log('Context:', context2);
console.log('Query:', query2);
console.log('Response:', response2);
const result2 = await metric2.measure(query2, response2);
console.log('Metric Result:', {
score: result2.score,
reason: result2.info.reason,
});
// Example Output:
// Metric Result: { score: 0.5, reason: 'The context uses some relevant information and includes some irrelevant information.' }
Low Precision Example
Evaluate a response where most context is irrelevant:
src/index.ts
const context3 = [
'The Nile River is in Africa.',
'The Nile is the longest river.',
'Ancient Egyptians used the Nile.',
'The Nile flows north.',
];
const metric3 = new ContextPrecisionMetric(openai('gpt-4o-mini'), {
context: context3,
});
const query3 = 'Which direction does the Nile River flow?';
const response3 = 'The Nile River flows northward.';
console.log('Example 3 - Low Precision:');
console.log('Context:', context3);
console.log('Query:', query3);
console.log('Response:', response3);
const result3 = await metric3.measure(query3, response3);
console.log('Metric Result:', {
score: result3.score,
reason: result3.info.reason,
});
// Example Output:
// Metric Result: { score: 0.2, reason: 'The context only has one relevant piece, which is at the end.' }
Understanding the Results
The metric provides:
-
A precision score between 0 and 1:
- 1.0: Perfect precision - all context pieces are relevant and used
- 0.7-0.9: High precision - most context pieces are relevant
- 0.4-0.6: Mixed precision - some context pieces are relevant
- 0.1-0.3: Low precision - few context pieces are relevant
- 0.0: No precision - no context pieces are relevant
-
Detailed reason for the score, including analysis of:
- Relevance of each context piece
- Usage in the response
- Contribution to answering the query
- Overall context usefulness
View Example on GitHub