
Name	DeepEvalEvaluator
Path	https://github.com/deepset-ai/haystack-core-integrations/tree/main/integrations/deepeval
Most common Position in a Pipeline	On its own or in an evaluation Pipeline. To be used after a separate Pipeline has generated the inputs for the Evaluator.
Mandatory Input variables	“inputs”: a keyword arguments dictionary containing the expected inputs. The expected inputs will change based on what metric you are evaluating. See below for more details.
Output variables	“results”: a nested list of metric results. There can be one or more results, depending on the metric. Each result is a dictionary containing: - `name` - The name of the metric. - `score` - The score of the metric. - `explanation` - An optional explanation of the score.

DeepEval is an evaluation framework that provides a number of LLM-based evaluation metrics. You can use the DeepEvalEvaluator component to evaluate a Haystack Pipeline, such as a retrieval-augmented generated Pipeline, against one of the metrics provided by DeepEval.

Supported Metrics

DeepEval supports a number of metrics, which we expose through the DeepEval metric enumeration. DeepEvalEvaluator in Haystack supports the metrics listed below with the expected metric_params while initializing the Evaluator. Many metrics use OpenAI models and require you to set an environment variable OPENAI_API_KEY. For a complete guide on these metrics, visit the DeepEval documentation.

Metric	Metric Parameters	Expected inputs	Metric description
`ANSWER_RELEVANCY`	`model: str`	`questions: List[str]`, `contexts: List[List[str]]`, `responses: List[str]`	Grades how relevant the answer was to the question specified.
`FAITHFULNESS`	`model: str`	`questions: List[str]`, `contexts: List[List[str]]`, `responses: List[str]`	Grades how factual the generated response was.
`CONTEXTUAL_PRECISION`	`model: str`	`questions: List[str]`, `contexts: List[List[str]]`, `responses: List[str]`, `ground_truths: List[str]`	Grades if the answer has any additional irrelevant information for the question asked.
`CONTEXTUAL_RECALL`	`model: str`	`questions: List[str]`, `contexts: List[List[str]]`, `responses: List[str]`, `ground_truths: List[str]`	Grades how complete the generated response was for the question specified.
`CONTEXTUAL_RELEVANCE`	`model: str`	`questions: List[str]`, `contexts: List[List[str]]`, `responses: List[str]`	Grades how relevant the provided context was for the question specified.

Parameters Overview

To initialize a DeepEvalEvaluator, you need to provide the following parameters :

metric: A DeepEvalMetric.
metric_params: Optionally, if the metric calls for any additional parameters, you should provide them here.

Usage

To use the DeepEvalEvaluator, you first need to install the integration:

pip install deepeval-haystack

To use the DeepEvalEvaluator you need to follow these steps:

Initialize the DeepEvalEvaluator while providing the correct metric_params for the metric you are using.
Run the DeepEvalEvaluator on its own or in a Pipeline by providing the expected input for the metric you are using.

Examples

Evaluate Faithfulness

To create a faithfulness evaluation Pipeline:

from haystack import Pipeline
from haystack_integrations.components.evaluators.deepeval import DeepEvalEvaluator, DeepEvalMetric

pipeline = Pipeline()
evaluator = DeepEvalEvaluator(
    metric=DeepEvalMetric.FAITHFULNESS,
    metric_params={"model": "gpt-4"},
)
pipeline.add_component("evaluator", evaluator)

To run the evaluation Pipeline, you should have the expected inputs for the metric ready at hand. This metric expects a list of questions and contexts. These should come from the results of the Pipeline you want to evaluate.

results = pipeline.run({"evaluator": {"questions": ["When was the Rhodes Statue built?", "Where is the Pyramid of Giza?"], 
                                      "contexts": [["Context for question 1"], ["Context for question 2"]],
                                      "responses": ["Response for queston 1", "Reponse for question 2"]}})