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0-11.315-11.314zM212.852 43.14a56.002 56.002 0 0 0-79.196 0l-28.284 28.284a8 8 0 1 0 11.314 11.314l28.284-28.284a40 40 0 0 1 56.568 56.567l-28.285 28.285a8 8 0 0 0 11.315 11.314l28.284-28.284a56.065 56.065 0 0 0 0-79.196z" fill="currentColor"></path></svg></span></a> <span>本章简介</span></h1> <div class="flex space-x-1 absolute z-10 right-0 top-0" style=""><a href="https://discuss.huggingface.co/t/chapter-2-questions" target="_blank"><img alt="Ask a Question" class="!m-0" src="https://img.shields.io/badge/Ask%20a%20question-ffcb4c.svg?logo=data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgLTEgMTA0IDEwNiI+PGRlZnM+PHN0eWxlPi5jbHMtMXtmaWxsOiMyMzFmMjA7fS5jbHMtMntmaWxsOiNmZmY5YWU7fS5jbHMtM3tmaWxsOiMwMGFlZWY7fS5jbHMtNHtmaWxsOiMwMGE5NGY7fS5jbHMtNXtmaWxsOiNmMTVkMjI7fS5jbHMtNntmaWxsOiNlMzFiMjM7fTwvc3R5bGU+PC9kZWZzPjx0aXRsZT5EaXNjb3Vyc2VfbG9nbzwvdGl0bGU+PGcgaWQ9IkxheWVyXzIiPjxnIGlkPSJMYXllcl8zIj48cGF0aCBjbGFzcz0iY2xzLTEiIGQ9Ik01MS44NywwQzIzLjcxLDAsMCwyMi44MywwLDUxYzAsLjkxLDAsNTIuODEsMCw1Mi44MWw1MS44Ni0uMDVjMjguMTYsMCw1MS0yMy43MSw1MS01MS44N1M4MCwwLDUxLjg3LDBaIi8+PHBhdGggY2xhc3M9ImNscy0yIiBkPSJNNTIuMzcsMTkuNzRBMzEuNjIsMzEuNjIsMCwwLDAsMjQuNTgsNjYuNDFsLTUuNzIsMTguNEwzOS40LDgwLjE3YTMxLjYxLDMxLjYxLDAsMSwwLDEzLTYwLjQzWiIvPjxwYXRoIGNsYXNzPSJjbHMtMyIgZD0iTTc3LjQ1LDMyLjEyYTMxLjYsMzEuNiwwLDAsMS0zOC4wNSw0OEwxOC44Niw4NC44MmwyMC45MS0yLjQ3QTMxLjYsMzEuNiwwLDAsMCw3Ny40NSwzMi4xMloiLz48cGF0aCBjbGFzcz0iY2xzLTQiIGQ9Ik03MS42MywyNi4yOUEzMS42LDMxLjYsMCwwLDEsMzguOCw3OEwxOC44Niw4NC44MiwzOS40LDgwLjE3QTMxLjYsMzEuNiwwLDAsMCw3MS42MywyNi4yOVoiLz48cGF0aCBjbGFzcz0iY2xzLTUiIGQ9Ik0yNi40Nyw2Ny4xMWEzMS42MSwzMS42MSwwLDAsMSw1MS0zNUEzMS42MSwzMS42MSwwLDAsMCwyNC41OCw2Ni40MWwtNS43MiwxOC40WiIvPjxwYXRoIGNsYXNzPSJjbHMtNiIgZD0iTTI0LjU4LDY2LjQxQTMxLjYxLDMxLjYxLDAsMCwxLDcxLjYzLDI2LjI5YTMxLjYxLDMxLjYxLDAsMCwwLTQ5LDM5LjYzbC0zLjc2LDE4LjlaIi8+PC9nPjwvZz48L3N2Zz4="></a>  </div> <p data-svelte-h="svelte-kzps0h">正如你在 <a href="/course/chapter1">第一章</a> ，中看到的那样，Transformers 模型通常规模庞大。包含数以百万计到数千万计数十亿的参数，训练和部署这些模型是一项复杂的任务。再者，新模型的推出几乎日新月异，而每种模型都有其独特的实现方式，尝试全部模型绝非易事。</p> <p data-svelte-h="svelte-1n7vpa">🤗 Transformers 库应运而生，就是为了解决这个问题。它的目标是提供一个统一的 API 接口，通过它可以加载、训练和保存任何 Transformer 模型。该库的主要特点有：</p> <ul data-svelte-h="svelte-gz80c6"><li><strong>易于使用</strong>：仅需两行代码，就能下载、加载并使用先进的 NLP 模型进行推理。</li> <li><strong>灵活</strong>：在本质上，所有的模型都是简单的 PyTorch nn.Module 或 TensorFlow tf.keras.Model 类，并可像在各自的机器学习（ML）框架中处理其他模型一样处理它们。</li> <li><strong>简单</strong>：该库几乎没有进行任何抽象化。🤗 Transformers 库一个核心概念是“全在一个文件中”：模型的前向传播完全在一个文件中定义，这使得代码本身易于理解和修改。</li></ul> <p data-svelte-h="svelte-qyb0i3">最后一个特性使🤗 Transformers 与其他 ML 库截然不同。模型并非建立在跨越多个代码文件共享的模块上；相反，每一个模型都有自己的层次结构。除了使模型更加容易接受和更容易理解，这还允许你轻松地在一个模型上实验，而且不影响其他模型。</p> <p data-svelte-h="svelte-6emoa7">本章将从一个端到端（从输入端到输出端）的示例开始，在该示例中，我们一起使用模型和 tokenizer 来复刻 <a href="/course/chapter1">第一章</a> 中看到的 <code>pipeline()</code> 函数。接下来，我们将讨论 <code>Model</code> API：我们将深入研究 <code>Model</code> 类和 <code>Config</code> 类，并向你展示如何加载模型，以及它如何将输入处理为输出。</p> <p data-svelte-h="svelte-1croyj">然后我们来看看 <code>tokenizer</code> API，它是 <code>pipeline()</code> 函数的另一个重要组成部分。在 <code>pipeline()</code> 中 <code>Tokenizer</code> 负责第一步和最后一步的处理，将文本转换到神经网络的输入，以及在需要时将其转换回文本。最后，我们将向你展示如何处理将多个句子整理为一个 batch 发送给模型，然后我们将更深入地研究 <code>tokenizer()</code> 函数。</p> <blockquote class="tip" data-svelte-h="svelte-fdmg1t"><p>⚠️ 为了充分利用 Model Hub 和🤗 Transformers 提供的所有功能，我们建议你<a href="https://huggingface.co/join">创建一个账户</a>。</p></blockquote> <a class="!text-gray-400 !no-underline text-sm flex items-center not-prose mt-4" href="https://github.com/huggingface/course/blob/main/chapters/zh-CN/chapter2/1.mdx" target="_blank"><svg class="mr-1" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" fill="currentColor" focusable="false" role="img" width="1em" height="1em" preserveAspectRatio="xMidYMid meet" viewBox="0 0 32 32"><path d="M31,16l-7,7l-1.41-1.41L28.17,16l-5.58-5.59L24,9l7,7z"></path><path d="M1,16l7-7l1.41,1.41L3.83,16l5.58,5.59L8,23l-7-7z"></path><path d="M12.419,25.484L17.639,6.552l1.932,0.518L14.351,26.002z"></path></svg> <span data-svelte-h="svelte-zjs2n5"><span class="underline">Update</span> on GitHub</span></a>  <p></p> 
			
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