BERTopic/bertopic/representation/_llamacpp.py

import pandas as pd
from tqdm import tqdm
from scipy.sparse import csr_matrix
from llama_cpp import Llama
from typing import Mapping, List, Tuple, Any, Union, Callable
from bertopic.representation._base import BaseRepresentation
from bertopic.representation._utils import truncate_document


DEFAULT_PROMPT = """
Q: I have a topic that contains the following documents:
[DOCUMENTS]

The topic is described by the following keywords: '[KEYWORDS]'.

Based on the above information, can you give a short label of the topic?
A: """


class LlamaCPP(BaseRepresentation):
    """ A llama.cpp implementation to use as a representation model.

    Arguments:
        model: Either a string pointing towards a local LLM or a 
                `llama_cpp.Llama` object.       
        prompt: The prompt to be used in the model. If no prompt is given,
                `self.default_prompt_` is used instead.
                NOTE: Use `"[KEYWORDS]"` and `"[DOCUMENTS]"` in the prompt
                to decide where the keywords and documents need to be
                inserted.
        pipeline_kwargs: Kwargs that you can pass to the `llama_cpp.Llama`
                         when it is called such as `max_tokens` to be generated.
        nr_docs: The number of documents to pass to OpenAI if a prompt
                 with the `["DOCUMENTS"]` tag is used.
        diversity: The diversity of documents to pass to OpenAI.
                   Accepts values between 0 and 1. A higher
                   values results in passing more diverse documents
                   whereas lower values passes more similar documents.
        doc_length: The maximum length of each document. If a document is longer,
                    it will be truncated. If None, the entire document is passed.
        tokenizer: The tokenizer used to calculate to split the document into segments
                   used to count the length of a document.
                       * If tokenizer is 'char', then the document is split up
                         into characters which are counted to adhere to `doc_length`
                       * If tokenizer is 'whitespace', the the document is split up
                         into words separated by whitespaces. These words are counted
                         and truncated depending on `doc_length`
                       * If tokenizer is 'vectorizer', then the internal CountVectorizer
                         is used to tokenize the document. These tokens are counted
                         and trunctated depending on `doc_length`
                       * If tokenizer is a callable, then that callable is used to tokenize
                         the document. These tokens are counted and truncated depending
                         on `doc_length`

    Usage:

    To use a llama.cpp, first download the LLM:

    ```bash
    wget https://huggingface.co/TheBloke/zephyr-7B-alpha-GGUF/resolve/main/zephyr-7b-alpha.Q4_K_M.gguf
    ```

    Then, we can now use the model the model with BERTopic in just a couple of lines:

    ```python
    from bertopic import BERTopic
    from bertopic.representation import LlamaCPP

    # Use llama.cpp to load in a 4-bit quantized version of Zephyr 7B Alpha
    representation_model = LlamaCPP("zephyr-7b-alpha.Q4_K_M.gguf")

    # Create our BERTopic model
    topic_model = BERTopic(representation_model=representation_model, verbose=True)
    ```

    If you want to have more control over the LLMs parameters, you can run it like so:

    ```python
    from bertopic import BERTopic
    from bertopic.representation import LlamaCPP
    from llama_cpp import Llama

    # Use llama.cpp to load in a 4-bit quantized version of Zephyr 7B Alpha
    llm = Llama(model_path="zephyr-7b-alpha.Q4_K_M.gguf", n_gpu_layers=-1, n_ctx=4096, stop="Q:")
    representation_model = LlamaCPP(llm)

    # Create our BERTopic model
    topic_model = BERTopic(representation_model=representation_model, verbose=True)
    ```
    """
    def __init__(self,
                 model: Union[str, Llama],
                 prompt: str = None,
                 pipeline_kwargs: Mapping[str, Any] = {},
                 nr_docs: int = 4,
                 diversity: float = None,
                 doc_length: int = None,
                 tokenizer: Union[str, Callable] = None
                 ):
        if isinstance(model, str):
            self.model = Llama(model_path=model, n_gpu_layers=-1, stop="Q:")
        elif isinstance(model, Llama):
            self.model = model
        else:
            raise ValueError("Make sure that the model that you"
                             "pass is either a string referring to a"
                             "local LLM or a ` llama_cpp.Llama` object.")
        self.prompt = prompt if prompt is not None else DEFAULT_PROMPT
        self.default_prompt_ = DEFAULT_PROMPT
        self.pipeline_kwargs = pipeline_kwargs
        self.nr_docs = nr_docs
        self.diversity = diversity
        self.doc_length = doc_length
        self.tokenizer = tokenizer

        self.prompts_ = []

    def extract_topics(self,
                       topic_model,
                       documents: pd.DataFrame,
                       c_tf_idf: csr_matrix,
                       topics: Mapping[str, List[Tuple[str, float]]]
                       ) -> Mapping[str, List[Tuple[str, float]]]:
        """ Extract topic representations and return a single label

        Arguments:
            topic_model: A BERTopic model
            documents: Not used
            c_tf_idf: Not used
            topics: The candidate topics as calculated with c-TF-IDF

        Returns:
            updated_topics: Updated topic representations
        """
        # Extract the top 4 representative documents per topic
        repr_docs_mappings, _, _, _ = topic_model._extract_representative_docs(
            c_tf_idf,
            documents,
            topics,
            500,
            self.nr_docs,
            self.diversity
        )

        updated_topics = {}
        for topic, docs in tqdm(repr_docs_mappings.items(), disable=not topic_model.verbose):

            # Prepare prompt
            truncated_docs = [truncate_document(topic_model, self.doc_length, self.tokenizer, doc) for doc in docs]
            prompt = self._create_prompt(truncated_docs, topic, topics)
            self.prompts_.append(prompt)

            # Extract result from generator and use that as label
            topic_description = self.model(prompt, **self.pipeline_kwargs)['choices']
            topic_description = [(description["text"].replace(prompt, ""), 1) for description in topic_description]

            if len(topic_description) < 10:
                topic_description += [("", 0) for _ in range(10-len(topic_description))]

            updated_topics[topic] = topic_description

        return updated_topics

    def _create_prompt(self, docs, topic, topics):
        keywords = ", ".join(list(zip(*topics[topic]))[0])

        # Use the default prompt and replace keywords
        if self.prompt == DEFAULT_PROMPT:
            prompt = self.prompt.replace("[KEYWORDS]", keywords)

        # Use a prompt that leverages either keywords or documents in
        # a custom location
        else:
            prompt = self.prompt
            if "[KEYWORDS]" in prompt:
                prompt = prompt.replace("[KEYWORDS]", keywords)
            if "[DOCUMENTS]" in prompt:
                to_replace = ""
                for doc in docs:
                    to_replace += f"- {doc}\n"
                prompt = prompt.replace("[DOCUMENTS]", to_replace)

        return prompt