语言模型有 token 限制。您不应超过 token 限制。因此，当您将文本分割成块时，计算 token 数量是个好主意。有许多分词器。当您计算文本中的 token 时，应使用与语言模型中相同的分词器。

​
tiktoken

tiktoken 是由 OpenAI 创建的快速 BPE 分词器。
我们可以使用 tiktoken 来估算使用的 token。对于 OpenAI 模型，它可能会更准确。
  1. 文本如何分割：通过传入的字符。
  2. 块大小如何测量：通过 tiktoken 分词器。
@[CharacterTextSplitter]、@[RecursiveCharacterTextSplitter] 和 @[TokenTextSplitter] 可以直接与 tiktoken 一起使用。 
pip install --upgrade --quiet langchain-text-splitters tiktoken

from langchain_text_splitters import CharacterTextSplitter

# 这是一个可以分割的长文档。
with open("state_of_the_union.txt") as f:
    state_of_the_union = f.read()
要使用 @[CharacterTextSplitter] 分割，然后使用 tiktoken 合并块，请使用其 .from_tiktoken_encoder() 方法。请注意，此方法的分割可能大于 tiktoken 分词器测量的块大小。 .from_tiktoken_encoder() 方法接受 encoding_name 作为参数（例如 cl100k_base），或 model_name（例如 gpt-4）。所有其他参数（如 chunk_size、chunk_overlap 和 separators）用于实例化 CharacterTextSplitter： 
text_splitter = CharacterTextSplitter.from_tiktoken_encoder(
    encoding_name="cl100k_base", chunk_size=100, chunk_overlap=0
)
texts = text_splitter.split_text(state_of_the_union)

print(texts[0])

Madam Speaker, Madam Vice President, our First Lady and Second Gentleman. Members of Congress and the Cabinet. Justices of the Supreme Court. My fellow Americans.

Last year COVID-19 kept us apart. This year we are finally together again.

Tonight, we meet as Democrats Republicans and Independents. But most importantly as Americans.

With a duty to one another to the American people to the Constitution.
要对块大小实施硬约束，我们可以使用 RecursiveCharacterTextSplitter.from_tiktoken_encoder，如果分割的大小更大，则每个分割将被递归分割： 
from langchain_text_splitters import RecursiveCharacterTextSplitter

text_splitter = RecursiveCharacterTextSplitter.from_tiktoken_encoder(
    model_name="gpt-4",
    chunk_size=100,
    chunk_overlap=0,
)
我们还可以加载 TokenTextSplitter 分割器，它直接与 tiktoken 配合使用，并确保每个分割小于块大小。 
from langchain_text_splitters import TokenTextSplitter

text_splitter = TokenTextSplitter(chunk_size=10, chunk_overlap=0)

texts = text_splitter.split_text(state_of_the_union)
print(texts[0])

Madam Speaker, Madam Vice President, our
某些书面语言（例如中文和日语）的字符编码为两个或多个 token。直接使用 TokenTextSplitter 可能会在两个块之间分割字符的 token，导致 Unicode 字符格式错误。使用 RecursiveCharacterTextSplitter.from_tiktoken_encoder 或 CharacterTextSplitter.from_tiktoken_encoder 以确保块包含有效的 Unicode 字符串。

​
spaCy

spaCy 是一个用于高级自然语言处理的开源软件库，使用 Python 和 Cython 编程语言编写。
LangChain 实现了基于 spaCy 分词器 的分割器。
  1. 文本如何分割：通过 spaCy 分词器。
  2. 块大小如何测量：按字符数。
pip install --upgrade --quiet  spacy

# This is a long document we can split up.
with open("state_of_the_union.txt") as f:
    state_of_the_union = f.read()

from langchain_text_splitters import SpacyTextSplitter

text_splitter = SpacyTextSplitter(chunk_size=1000)

texts = text_splitter.split_text(state_of_the_union)
print(texts[0])

Madam Speaker, Madam Vice President, our First Lady and Second Gentleman.

Members of Congress and the Cabinet.

Justices of the Supreme Court.

My fellow Americans.



Last year COVID-19 kept us apart.

This year we are finally together again.



Tonight, we meet as Democrats Republicans and Independents.

But most importantly as Americans.



With a duty to one another to the American people to the Constitution.



And with an unwavering resolve that freedom will always triumph over tyranny.



Six days ago, Russia’s Vladimir Putin sought to shake the foundations of the free world thinking he could make it bend to his menacing ways.

But he badly miscalculated.



He thought he could roll into Ukraine and the world would roll over.

Instead he met a wall of strength he never imagined.



He met the Ukrainian people.



From President Zelenskyy to every Ukrainian, their fearlessness, their courage, their determination, inspires the world.

​
SentenceTransformers

SentenceTransformersTokenTextSplitter 是专门用于 sentence-transformer 模型的文本分割器。默认行为是将文本分割成适合您要使用的 sentence transformer 模型的 token 窗口的块。 要根据 sentence-transformers 分词器分割文本并约束 token 计数，请实例化 SentenceTransformersTokenTextSplitter。您可以选择指定：
  • chunk_overlap：token 重叠的整数计数；
  • model_name：sentence-transformer 模型名称，默认为 "sentence-transformers/all-mpnet-base-v2"；
  • tokens_per_chunk：每个块所需的 token 计数。
from langchain_text_splitters import SentenceTransformersTokenTextSplitter

splitter = SentenceTransformersTokenTextSplitter(chunk_overlap=0)
text = "Lorem "

count_start_and_stop_tokens = 2
text_token_count = splitter.count_tokens(text=text) - count_start_and_stop_tokens
print(text_token_count)

2

token_multiplier = splitter.maximum_tokens_per_chunk // text_token_count + 1

# `text_to_split` does not fit in a single chunk
text_to_split = text * token_multiplier

print(f"tokens in text to split: {splitter.count_tokens(text=text_to_split)}")

tokens in text to split: 514

text_chunks = splitter.split_text(text=text_to_split)

print(text_chunks[1])

lorem

​
NLTK

自然语言工具包，或更常见的 NLTK，是一套用于英语符号和统计自然语言处理 (NLP) 的库和程序，使用 Python 编程语言编写。
我们不仅可以在 “\n\n” 上分割，还可以使用 NLTK 基于 NLTK 分词器 进行分割。
  1. 文本如何分割：通过 NLTK 分词器。
  2. 块大小如何测量：按字符数。
# pip install nltk

# This is a long document we can split up.
with open("state_of_the_union.txt") as f:
    state_of_the_union = f.read()

from langchain_text_splitters import NLTKTextSplitter

text_splitter = NLTKTextSplitter(chunk_size=1000)

texts = text_splitter.split_text(state_of_the_union)
print(texts[0])

Madam Speaker, Madam Vice President, our First Lady and Second Gentleman.

Members of Congress and the Cabinet.

Justices of the Supreme Court.

My fellow Americans.

Last year COVID-19 kept us apart.

This year we are finally together again.

Tonight, we meet as Democrats Republicans and Independents.

But most importantly as Americans.

With a duty to one another to the American people to the Constitution.

And with an unwavering resolve that freedom will always triumph over tyranny.

Six days ago, Russia’s Vladimir Putin sought to shake the foundations of the free world thinking he could make it bend to his menacing ways.

But he badly miscalculated.

He thought he could roll into Ukraine and the world would roll over.

Instead he met a wall of strength he never imagined.

He met the Ukrainian people.

From President Zelenskyy to every Ukrainian, their fearlessness, their courage, their determination, inspires the world.

Groups of citizens blocking tanks with their bodies.

​
KoNLPY

KoNLPy: Python 中的韩语 NLP 是一个用于韩语自然语言处理 (NLP) 的 Python 包。
Token 分割涉及将文本分割成更小、更易管理的单元，称为 token。这些 token 通常是单词、短语、符号或其他对进一步处理和分析至关重要的有意义元素。在英语等语言中，token 分割通常涉及通过空格和标点符号分隔单词。token 分割的有效性在很大程度上取决于分词器对语言结构的理解，确保生成有意义的 token。由于为英语设计的分词器无法理解其他语言（如韩语）的独特语义结构，因此它们不能有效地用于韩语处理。

​
使用 KoNLPy 的 Kkma 分析器进行韩语 token 分割

对于韩语文本，KoNLPY 包含一个称为 Kkma（韩语知识形态素分析器）的形态分析器。Kkma 提供韩语文本的详细形态分析。它将句子分解为单词，将单词分解为各自的形态素，并为每个 token 识别词性。它可以将文本块分割成单独的句子，这对于处理长文本特别有用。

​
使用注意事项

虽然 Kkma 以其详细分析而闻名，但需要注意的是，这种精确性可能会影响处理速度。因此，Kkma 最适合优先考虑分析深度而非快速文本处理的应用。 
# pip install konlpy

# 这是一个我们想要分割成其组成句子的长韩语文档。
with open("./your_korean_doc.txt") as f:
    korean_document = f.read()

from langchain_text_splitters import KonlpyTextSplitter

text_splitter = KonlpyTextSplitter()

texts = text_splitter.split_text(korean_document)
# 句子用 "\n\n" 字符分割。
print(texts[0])

춘향전 옛날에 남원에 이 도령이라는 벼슬아치 아들이 있었다.

그의 외모는 빛나는 달처럼 잘생겼고, 그의 학식과 기예는 남보다 뛰어났다.

한편, 이 마을에는 춘향이라는 절세 가인이 살고 있었다.

춘 향의 아름다움은 꽃과 같아 마을 사람들 로부터 많은 사랑을 받았다.

어느 봄날, 도령은 친구들과 놀러 나갔다가 춘 향을 만 나 첫 눈에 반하고 말았다.

두 사람은 서로 사랑하게 되었고, 이내 비밀스러운 사랑의 맹세를 나누었다.

하지만 좋은 날들은 오래가지 않았다.

도령의 아버지가 다른 곳으로 전근을 가게 되어 도령도 떠나 야만 했다.

이별의 아픔 속에서도, 두 사람은 재회를 기약하며 서로를 믿고 기다리기로 했다.

그러나 새로 부임한 관아의 사또가 춘 향의 아름다움에 욕심을 내 어 그녀에게 강요를 시작했다.

춘 향 은 도령에 대한 자신의 사랑을 지키기 위해, 사또의 요구를 단호히 거절했다.

이에 분노한 사또는 춘 향을 감옥에 가두고 혹독한 형벌을 내렸다.

이야기는 이 도령이 고위 관직에 오른 후, 춘 향을 구해 내는 것으로 끝난다.

두 사람은 오랜 시련 끝에 다시 만나게 되고, 그들의 사랑은 온 세상에 전해 지며 후세에까지 이어진다.

- 춘향전 (The Tale of Chunhyang)

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Hugging Face 分词器

Hugging Face 有许多分词器。 我们使用 Hugging Face 分词器 GPT2TokenizerFast 来计算文本的 token 长度。
  1. 文本如何分割：通过传入的字符。
  2. 块大小如何测量：通过 Hugging Face 分词器计算的 token 数。
from transformers import GPT2TokenizerFast

tokenizer = GPT2TokenizerFast.from_pretrained("gpt2")

# 这是一个可以分割的长文档。
with open("state_of_the_union.txt") as f:
    state_of_the_union = f.read()
from langchain_text_splitters import CharacterTextSplitter

text_splitter = CharacterTextSplitter.from_huggingface_tokenizer(
    tokenizer, chunk_size=100, chunk_overlap=0
)
texts = text_splitter.split_text(state_of_the_union)

print(texts[0])

Madam Speaker, Madam Vice President, our First Lady and Second Gentleman. Members of Congress and the Cabinet. Justices of the Supreme Court. My fellow Americans.

Last year COVID-19 kept us apart. This year we are finally together again.

Tonight, we meet as Democrats Republicans and Independents. But most importantly as Americans.

With a duty to one another to the American people to the Constitution.
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