检索评估¶
本笔记本使用我们的 RetrieverEvaluator 来评估 LlamaIndex 中定义的任何检索器模块的质量。
我们指定了一组不同的评估指标：包括命中率（hit-rate）、平均倒数排名（MRR）、精确率（Precision）、召回率（Recall）、平均精度（AP）和归一化折损累积增益（NDCG）。对于任何给定问题，这些指标将比较检索结果与真实上下文的质量。
为了减轻创建评估数据集的初始负担，我们可以依赖合成数据生成。
安装配置¶
在此步骤中，我们加载数据（PG论文），将其解析为节点。随后使用简易向量索引对数据进行索引处理，并获取检索器。
%pip install llama-index-llms-openai
%pip install llama-index-readers-file
import nest_asyncio
nest_asyncio.apply()
from llama_index.core import VectorStoreIndex, SimpleDirectoryReader
from llama_index.core.node_parser import SentenceSplitter
from llama_index.llms.openai import OpenAI
下载数据
!mkdir -p 'data/paul_graham/'
!wget 'https://raw.githubusercontent.com/run-llama/llama_index/main/docs/docs/examples/data/paul_graham/paul_graham_essay.txt' -O 'data/paul_graham/paul_graham_essay.txt'
documents = SimpleDirectoryReader("./data/paul_graham/").load_data()
node_parser = SentenceSplitter(chunk_size=512)
nodes = node_parser.get_nodes_from_documents(documents)
# by default, the node ids are set to random uuids. To ensure same id's per run, we manually set them.
for idx, node in enumerate(nodes):
node.id_ = f"node_{idx}"
llm = OpenAI(model="gpt-4")
vector_index = VectorStoreIndex(nodes)
retriever = vector_index.as_retriever(similarity_top_k=2)
尝试检索功能¶
我们将在一个简单的数据集上测试检索功能。
retrieved_nodes = retriever.retrieve("What did the author do growing up?")
from llama_index.core.response.notebook_utils import display_source_node
for node in retrieved_nodes:
display_source_node(node, source_length=1000)
Node ID: node_38
Similarity: 0.814377909267451
Text: I also worked on spam filters, and did some more painting. I used to have dinners for a group of friends every thursday night, which taught me how to cook for groups. And I bought another building in Cambridge, a former candy factory (and later, twas said, porn studio), to use as an office.
One night in October 2003 there was a big party at my house. It was a clever idea of my friend Maria Daniels, who was one of the thursday diners. Three separate hosts would all invite their friends to one party. So for every guest, two thirds of the other guests would be people they didn't know but would probably like. One of the guests was someone I didn't know but would turn out to like a lot: a woman called Jessica Livingston. A couple days later I asked her out.
Jessica was in charge of marketing at a Boston investment bank. This bank thought it understood startups, but over the next year, as she met friends of mine from the startup world, she was surprised how different reality was. And ho...
Node ID: node_0
Similarity: 0.8122448657654567
Text: What I Worked On
February 2021
Before college the two main things I worked on, outside of school, were writing and programming. I didn't write essays. I wrote what beginning writers were supposed to write then, and probably still are: short stories. My stories were awful. They had hardly any plot, just characters with strong feelings, which I imagined made them deep.
The first programs I tried writing were on the IBM 1401 that our school district used for what was then called "data processing." This was in 9th grade, so I was 13 or 14. The school district's 1401 happened to be in the basement of our junior high school, and my friend Rich Draves and I got permission to use it. It was like a mini Bond villain's lair down there, with all these alien-looking machines — CPU, disk drives, printer, card reader — sitting up on a raised floor under bright fluorescent lights.
The language we used was an early version of Fortran. You had to type programs on punch cards, then stack them in ...
构建（查询，上下文）对的评估数据集¶
这里我们在现有文本语料库上构建一个简单的评估数据集。
我们使用 generate_question_context_pairs 方法在给定的非结构化文本语料库上生成一组（问题，上下文）对。该方法利用大语言模型（LLM）自动从每个上下文片段生成问题。
最终返回一个 EmbeddingQAFinetuneDataset 对象。从高层次来看，该对象包含：一组映射到查询和相关文档片段的ID集合，以及语料库本身。
from llama_index.core.evaluation import (
generate_question_context_pairs,
EmbeddingQAFinetuneDataset,
)
qa_dataset = generate_question_context_pairs(
nodes, llm=llm, num_questions_per_chunk=2
)
100%|██████████| 61/61 [06:10<00:00, 6.08s/it]
queries = qa_dataset.queries.values()
print(list(queries)[2])
"Describe the transition from using the IBM 1401 to microcomputers, as mentioned in the text. What were the key differences and how did these changes impact the user's interaction with the computer?"
# [optional] save
qa_dataset.save_json("pg_eval_dataset.json")
# [optional] load
qa_dataset = EmbeddingQAFinetuneDataset.from_json("pg_eval_dataset.json")
使用 RetrieverEvaluator 进行检索评估¶
现在我们已经准备好运行检索评估了。我们将在生成的评估数据集上运行 RetrieverEvaluator。
我们定义了两个函数：get_eval_results 和 display_results，用于在数据集上运行检索器。
include_cohere_rerank = False
if include_cohere_rerank:
!pip install cohere -q
from llama_index.core.evaluation import RetrieverEvaluator
metrics = ["hit_rate", "mrr", "precision", "recall", "ap", "ndcg"]
if include_cohere_rerank:
metrics.append(
"cohere_rerank_relevancy" # requires COHERE_API_KEY environment variable to be set
)
retriever_evaluator = RetrieverEvaluator.from_metric_names(
metrics, retriever=retriever
)
# try it out on a sample query
sample_id, sample_query = list(qa_dataset.queries.items())[0]
sample_expected = qa_dataset.relevant_docs[sample_id]
eval_result = retriever_evaluator.evaluate(sample_query, sample_expected)
print(eval_result)
Query: Describe the author's initial experiences with programming on the IBM 1401. What challenges did he face and how did these experiences shape his understanding of programming?
Metrics: {'hit_rate': 1.0, 'mrr': 1.0, 'precision': 0.5, 'recall': 1.0, 'ap': 1.0, 'ndcg': 0.6131471927654584}
# try it out on an entire dataset
eval_results = await retriever_evaluator.aevaluate_dataset(qa_dataset)
Retrying llama_index.embeddings.openai.base.aget_embedding in 0.6914689476274432 seconds as it raised RateLimitError: Error code: 429 - {'statusCode': 429, 'message': 'Rate limit is exceeded. Try again in 3 seconds.'}.
Retrying llama_index.embeddings.openai.base.aget_embedding in 1.072244476250501 seconds as it raised RateLimitError: Error code: 429 - {'statusCode': 429, 'message': 'Rate limit is exceeded. Try again in 3 seconds.'}.
Retrying llama_index.embeddings.openai.base.aget_embedding in 0.8123380504307198 seconds as it raised RateLimitError: Error code: 429 - {'statusCode': 429, 'message': 'Rate limit is exceeded. Try again in 4 seconds.'}.
Retrying llama_index.embeddings.openai.base.aget_embedding in 0.9520260756712478 seconds as it raised RateLimitError: Error code: 429 - {'statusCode': 429, 'message': 'Rate limit is exceeded. Try again in 6 seconds.'}.
Retrying llama_index.embeddings.openai.base.aget_embedding in 1.3700745779005286 seconds as it raised RateLimitError: Error code: 429 - {'statusCode': 429, 'message': 'Rate limit is exceeded. Try again in 4 seconds.'}.
import pandas as pd
def display_results(name, eval_results):
"""Display results from evaluate."""
metric_dicts = []
for eval_result in eval_results:
metric_dict = eval_result.metric_vals_dict
metric_dicts.append(metric_dict)
full_df = pd.DataFrame(metric_dicts)
columns = {
"retrievers": [name],
**{k: [full_df[k].mean()] for k in metrics},
}
if include_cohere_rerank:
crr_relevancy = full_df["cohere_rerank_relevancy"].mean()
columns.update({"cohere_rerank_relevancy": [crr_relevancy]})
metric_df = pd.DataFrame(columns)
return metric_df
display_results("top-2 eval", eval_results)
| retrievers | hit_rate | mrr | precision | recall | ap | ndcg | |
|---|---|---|---|---|---|---|---|
| 0 | top-2 eval | 0.770492 | 0.655738 | 0.385246 | 0.770492 | 0.655738 | 0.420488 |