Repository: explodinggradients/ragas
Issue: Invalid n value (currently only n = 1 is supported
Root cause: Validation Gap

  File "/usr/local/lib/python3.10/dist-packages/ragas/langchain/evalchain.py", line 166, in evaluate
    dataset_with_scores = self.metric.score(dataset, callbacks=callbacks)
  File "/usr/local/lib/python3.10/dist-packages/ragas/metrics/base.py", line 76, in score
    score = self._score_batch(dataset.select(batch), callbacks=group)
  File "/usr/local/lib/python3.10/dist-packages/ragas/metrics/_answer_relevance.py", line 123, in _score_batch
    results = self.llm.generate(
  File "/usr/local/lib/python3.10/dist-packages/ragas/llms/langchain.py", line 209, in generate
    return self._generate_multiple_completions(prompts, n, callbacks)
  File "/usr/local/lib/python3.10/dist-packages/ragas/llms/langchain.py", line 120, in _generate_multiple_completions
    result = self.llm.generate(ps, callbacks=callbacks)
  File "/usr/local/lib/python3.10/dist-packages/langchain_core/language_models/chat_models.py", line 534, in generate
    raise e
  File "/usr/local/lib/python3.10/dist-packages/langchain_core/language_models/chat_models.py", line 524, in generate
    self._generate_with_cache(
  File "/usr/local/lib/python3.10/dist-packages/langchain_core/language_models/chat_models.py", line 749, in _generate_with_cache
    result = self._generate(
  File "/usr/local/lib/python3.10/dist-packages/langchain_community/chat_models/openai.py", line 442, in _generate
    response = self.completion_with_retry(
  File "/usr/local/lib/python3.10/dist-packages/langchain_community/chat_models/openai.py", line 357, in completion_with_retry
    return self.client.create(**kwargs)
  File "/usr/local/lib/python3.10/dist-packages/openai/_utils/_utils.py", line 277, in wrapper
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.10/dist-packages/openai/resources/chat/completions.py", line 643, in create
    return self._post(
  File "/usr/local/lib/python3.10/dist-packages/openai/_base_client.py", line 1250, in post
    return cast(ResponseT, self.request(cast_to, opts, stream=stream, stream_cls=stream_cls))
  File "/usr/local/lib/python3.10/dist-packages/openai/_base_client.py", line 931, in request
    return self._request(
  File "/usr/local/lib/python3.10/dist-packages/openai/_base_client.py", line 1030, in _request
    raise self._make_status_error_from_response(err.response) from None
openai.BadRequestError: Error code: 400 - {'detail': 'Invalid n value (currently only n = 1 is supported)'}



ragas=0.0.22  

<!-- Answer -->
To resolve the "Invalid n value (currently only n = 1 is supported)" error when using the `ragas` library version 0.0.22, ensure that the dataset you are passing to the `evaluate` function has the correct format and values. Specifically, the dataset should have the following columns: `question`, `contexts`, `answer`, and `ground_truth`.

Here is an example of how to structure your dataset and call the `evaluate` function:

```python
from ragas import evaluate
from datasets import Dataset

# Example dataset
data = {
    'question': ['What is the capital of France?'],
    'contexts': [['Paris is the capital of France.']],
    'answer': ['Paris'],
    'ground_truth': [['Paris']]
}

# Create a Dataset object
dataset = Dataset.from_dict(data)

# Call the evaluate function
result = evaluate(dataset)
print(result)
```

Ensure that the `contexts` and `ground_truth` columns are lists of strings, even if they contain only one string. This should resolve the error related to the "Invalid n value".

Additionally, the `ragas` library currently supports only `n = 1` for text generation. This is enforced in the library's code, where multiple completions are only supported for specific language models. If you are using a language model that does not support multiple completions, you will need to ensure that `n` is set to 1 <sup>[[1]](https://github.com/explodinggradients/ragas/blob/main/src/ragas/evaluation.py)</sup><sup>[[2]](https://github.com/explodinggradients/ragas/blob/main/src/ragas/llms/base.py)</sup>.


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