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-{
- "cells": [
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "# Transformer源代码解释之PyTorch篇\n",
- "在阅读完[2.2-图解transformer](./篇章2-Transformer相关原理/2.2-图解transformer.md)之后,希望大家能对transformer各个模块的设计和计算有一个形象的认识,本小节我们基于pytorch来实现一个Transformer,帮助大家进一步学习这个复杂的模型。\n",
- "**章节**\n",
- "\n",
- "- [词嵌入](#embed)\n",
- "- [位置编码](#pos)\n",
- "- [多头注意力](#multihead)\n",
- "- [搭建Transformer](#build)\n",
- "\n",
- "\n",
- "\n",
- "图:Transformer结构图"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "## **
词嵌入
**\n",
- "\n",
- "如上图所示,Transformer图里左边的是Encoder,右边是Decoder部分。Encoder输入源语言序列,Decoder里面输入需要被翻译的语言文本(在训练时)。一个文本常有许多序列组成,常见操作为将序列进行一些预处理(如词切分等)变成列表,一个序列的列表的元素通常为词表中不可切分的最小词,整个文本就是一个大列表,元素为一个一个由序列组成的列表。如一个序列经过切分后变为[\"am\", \"##ro\", \"##zi\", \"meets\", \"his\", \"father\"],接下来按照它们在词表中对应的索引进行转换,假设结果如[23, 94, 13, 41, 27, 96]。假如整个文本一共100个句子,那么就有100个列表为它的元素,因为每个序列的长度不一,需要设定最大长度,这里不妨设为128,那么将整个文本转换为数组之后,形状即为100 x 128,这就对应着batch_size和seq_length。\n",
- "\n",
- "输入之后,紧接着进行词嵌入处理,词嵌入就是将每一个词用预先训练好的向量进行映射。\n",
- "\n",
- "词嵌入在torch里基于`torch.nn.Embedding`实现,实例化时需要设置的参数为词表的大小和被映射的向量的维度比如`embed = nn.Embedding(10,8)`。向量的维度通俗来说就是向量里面有多少个数。注意,第一个参数是词表的大小,如果你目前最多有8个词,通常填写10(多一个位置留给unk和pad),你后面万一进入与这8个词不同的词就映射到unk上,序列padding的部分就映射到pad上。\n",
- "\n",
- "假如我们打算映射到8维(num_features或者embed_dim),那么,整个文本的形状变为100 x 128 x 8。接下来举个小例子解释一下:假设我们词表一共有10个词(算上unk和pad),文本里有2个句子,每个句子有4个词,我们想要把每个词映射到8维的向量。于是2,4,8对应于batch_size, seq_length, embed_dim(如果batch在第一维的话)。\n",
- "\n",
- "另外,一般深度学习任务只改变num_features,所以讲维度一般是针对最后特征所在的维度。\n",
- "\n",
- "开始编程:\n",
- "\n",
- "所有需要的包的导入:"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 1,
- "metadata": {},
- "outputs": [],
- "source": [
- "import torch\n",
- "import torch.nn as nn\n",
- "from torch.nn.parameter import Parameter\n",
- "from torch.nn.init import xavier_uniform_\n",
- "from torch.nn.init import constant_\n",
- "from torch.nn.init import xavier_normal_\n",
- "import torch.nn.functional as F\n",
- "from typing import Optional, Tuple, Any\n",
- "from typing import List, Optional, Tuple\n",
- "import math\n",
- "import warnings"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 2,
- "metadata": {},
- "outputs": [
- {
- "name": "stdout",
- "output_type": "stream",
- "text": [
- "torch.Size([2, 4, 8])\n"
- ]
- }
- ],
- "source": [
- "X = torch.zeros((2,4),dtype=torch.long)\n",
- "embed = nn.Embedding(10,8)\n",
- "print(embed(X).shape)"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "## **位置编码
**\n",
- "\n",
- "词嵌入之后紧接着就是位置编码,位置编码用以区分不同词以及同词不同特征之间的关系。代码中需要注意:X_只是初始化的矩阵,并不是输入进来的;完成位置编码之后会加一个dropout。另外,位置编码是最后加上去的,因此输入输出形状不变。\n"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 3,
- "metadata": {},
- "outputs": [],
- "source": [
- "Tensor = torch.Tensor\n",
- "def positional_encoding(X, num_features, dropout_p=0.1, max_len=512) -> Tensor:\n",
- " r'''\n",
- " 给输入加入位置编码\n",
- " 参数:\n",
- " - num_features: 输入进来的维度\n",
- " - dropout_p: dropout的概率,当其为非零时执行dropout\n",
- " - max_len: 句子的最大长度,默认512\n",
- " \n",
- " 形状:\n",
- " - 输入: [batch_size, seq_length, num_features]\n",
- " - 输出: [batch_size, seq_length, num_features]\n",
- "\n",
- " 例子:\n",
- " >>> X = torch.randn((2,4,10))\n",
- " >>> X = positional_encoding(X, 10)\n",
- " >>> print(X.shape)\n",
- " >>> torch.Size([2, 4, 10])\n",
- " '''\n",
- "\n",
- " dropout = nn.Dropout(dropout_p)\n",
- " P = torch.zeros((1,max_len,num_features))\n",
- " X_ = torch.arange(max_len,dtype=torch.float32).reshape(-1,1) / torch.pow(\n",
- " 10000,\n",
- " torch.arange(0,num_features,2,dtype=torch.float32) /num_features)\n",
- " P[:,:,0::2] = torch.sin(X_)\n",
- " P[:,:,1::2] = torch.cos(X_)\n",
- " X = X + P[:,:X.shape[1],:].to(X.device)\n",
- " return dropout(X)"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 4,
- "metadata": {},
- "outputs": [
- {
- "name": "stdout",
- "output_type": "stream",
- "text": [
- "torch.Size([2, 4, 10])\n"
- ]
- }
- ],
- "source": [
- "# 位置编码例子\n",
- "X = torch.randn((2,4,10))\n",
- "X = positional_encoding(X, 10)\n",
- "print(X.shape)"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "## **多头注意力
**"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "### 拆开看多头注意力机制\n",
- "**完整版本可运行的多头注意里机制的class在后面,先看一下完整的: 多头注意力机制-MultiheadAttention 小节再回来依次看下面的解释。**\n",
- "\n",
- "多头注意力类主要成分是:参数初始化、multi_head_attention_forward\n",
- "\n",
- "#### 初始化参数\n",
- "```python\n",
- "if self._qkv_same_embed_dim is False:\n",
- " # 初始化前后形状维持不变\n",
- " # (seq_length x embed_dim) x (embed_dim x embed_dim) ==> (seq_length x embed_dim)\n",
- " self.q_proj_weight = Parameter(torch.empty((embed_dim, embed_dim)))\n",
- " self.k_proj_weight = Parameter(torch.empty((embed_dim, self.kdim)))\n",
- " self.v_proj_weight = Parameter(torch.empty((embed_dim, self.vdim)))\n",
- " self.register_parameter('in_proj_weight', None)\n",
- "else:\n",
- " self.in_proj_weight = Parameter(torch.empty((3 * embed_dim, embed_dim)))\n",
- " self.register_parameter('q_proj_weight', None)\n",
- " self.register_parameter('k_proj_weight', None)\n",
- " self.register_parameter('v_proj_weight', None)\n",
- "\n",
- "if bias:\n",
- " self.in_proj_bias = Parameter(torch.empty(3 * embed_dim))\n",
- "else:\n",
- " self.register_parameter('in_proj_bias', None)\n",
- "# 后期会将所有头的注意力拼接在一起然后乘上权重矩阵输出\n",
- "# out_proj是为了后期准备的\n",
- "self.out_proj = nn.Linear(embed_dim, embed_dim, bias=bias)\n",
- "self._reset_parameters()\n",
- "```\n",
- "\n",
- "torch.empty是按照所给的形状形成对应的tensor,特点是填充的值还未初始化,类比torch.randn(标准正态分布),这就是一种初始化的方式。在PyTorch中,变量类型是tensor的话是无法修改值的,而Parameter()函数可以看作为一种类型转变函数,将不可改值的tensor转换为可训练可修改的模型参数,即与model.parameters绑定在一起,register_parameter的意思是是否将这个参数放到model.parameters,None的意思是没有这个参数。\n",
- "\n",
- "这里有个if判断,用以判断q,k,v的最后一维是否一致,若一致,则一个大的权重矩阵全部乘然后分割出来,若不是,则各初始化各的,其实初始化是不会改变原来的形状的(如,见注释)。\n",
- "\n",
- "可以发现最后有一个_reset_parameters()函数,这个是用来初始化参数数值的。xavier_uniform意思是从[连续型均匀分布](https://zh.wikipedia.org/wiki/%E9%80%A3%E7%BA%8C%E5%9E%8B%E5%9D%87%E5%8B%BB%E5%88%86%E5%B8%83)里面随机取样出值来作为初始化的值,xavier_normal_取样的分布是正态分布。正因为初始化值在训练神经网络的时候很重要,所以才需要这两个函数。\n",
- "\n",
- "constant_意思是用所给值来填充输入的向量。\n",
- "\n",
- "另外,在PyTorch的源码里,似乎projection代表是一种线性变换的意思,in_proj_bias的意思就是一开始的线性变换的偏置\n",
- "\n",
- "```python\n",
- "def _reset_parameters(self):\n",
- " if self._qkv_same_embed_dim:\n",
- " xavier_uniform_(self.in_proj_weight)\n",
- " else:\n",
- " xavier_uniform_(self.q_proj_weight)\n",
- " xavier_uniform_(self.k_proj_weight)\n",
- " xavier_uniform_(self.v_proj_weight)\n",
- " if self.in_proj_bias is not None:\n",
- " constant_(self.in_proj_bias, 0.)\n",
- " constant_(self.out_proj.bias, 0.)\n",
- "\n",
- "```\n",
- "\n"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "#### multi_head_attention_forward\n",
- "这个函数如下代码所示,主要分成3个部分:\n",
- "- query, key, value通过_in_projection_packed变换得到q,k,v\n",
- "- 遮挡机制\n",
- "- 点积注意力"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 5,
- "metadata": {},
- "outputs": [],
- "source": [
- "import torch\n",
- "Tensor = torch.Tensor\n",
- "def multi_head_attention_forward(\n",
- " query: Tensor,\n",
- " key: Tensor,\n",
- " value: Tensor,\n",
- " num_heads: int,\n",
- " in_proj_weight: Tensor,\n",
- " in_proj_bias: Optional[Tensor],\n",
- " dropout_p: float,\n",
- " out_proj_weight: Tensor,\n",
- " out_proj_bias: Optional[Tensor],\n",
- " training: bool = True,\n",
- " key_padding_mask: Optional[Tensor] = None,\n",
- " need_weights: bool = True,\n",
- " attn_mask: Optional[Tensor] = None,\n",
- " use_seperate_proj_weight = None,\n",
- " q_proj_weight: Optional[Tensor] = None,\n",
- " k_proj_weight: Optional[Tensor] = None,\n",
- " v_proj_weight: Optional[Tensor] = None,\n",
- ") -> Tuple[Tensor, Optional[Tensor]]:\n",
- " r'''\n",
- " 形状:\n",
- " 输入:\n",
- " - query:`(L, N, E)`\n",
- " - key: `(S, N, E)`\n",
- " - value: `(S, N, E)`\n",
- " - key_padding_mask: `(N, S)`\n",
- " - attn_mask: `(L, S)` or `(N * num_heads, L, S)`\n",
- " 输出:\n",
- " - attn_output:`(L, N, E)`\n",
- " - attn_output_weights:`(N, L, S)`\n",
- " '''\n",
- " tgt_len, bsz, embed_dim = query.shape\n",
- " src_len, _, _ = key.shape\n",
- " head_dim = embed_dim // num_heads\n",
- " q, k, v = _in_projection_packed(query, key, value, in_proj_weight, in_proj_bias)\n",
- "\n",
- " if attn_mask is not None:\n",
- " if attn_mask.dtype == torch.uint8:\n",
- " warnings.warn(\"Byte tensor for attn_mask in nn.MultiheadAttention is deprecated. Use bool tensor instead.\")\n",
- " attn_mask = attn_mask.to(torch.bool)\n",
- " else:\n",
- " assert attn_mask.is_floating_point() or attn_mask.dtype == torch.bool, \\\n",
- " f\"Only float, byte, and bool types are supported for attn_mask, not {attn_mask.dtype}\"\n",
- "\n",
- " if attn_mask.dim() == 2:\n",
- " correct_2d_size = (tgt_len, src_len)\n",
- " if attn_mask.shape != correct_2d_size:\n",
- " raise RuntimeError(f\"The shape of the 2D attn_mask is {attn_mask.shape}, but should be {correct_2d_size}.\")\n",
- " attn_mask = attn_mask.unsqueeze(0)\n",
- " elif attn_mask.dim() == 3:\n",
- " correct_3d_size = (bsz * num_heads, tgt_len, src_len)\n",
- " if attn_mask.shape != correct_3d_size:\n",
- " raise RuntimeError(f\"The shape of the 3D attn_mask is {attn_mask.shape}, but should be {correct_3d_size}.\")\n",
- " else:\n",
- " raise RuntimeError(f\"attn_mask's dimension {attn_mask.dim()} is not supported\")\n",
- "\n",
- " if key_padding_mask is not None and key_padding_mask.dtype == torch.uint8:\n",
- " warnings.warn(\"Byte tensor for key_padding_mask in nn.MultiheadAttention is deprecated. Use bool tensor instead.\")\n",
- " key_padding_mask = key_padding_mask.to(torch.bool)\n",
- " \n",
- " # reshape q,k,v将Batch放在第一维以适合点积注意力\n",
- " # 同时为多头机制,将不同的头拼在一起组成一层\n",
- " q = q.contiguous().view(tgt_len, bsz * num_heads, head_dim).transpose(0, 1)\n",
- " k = k.contiguous().view(-1, bsz * num_heads, head_dim).transpose(0, 1)\n",
- " v = v.contiguous().view(-1, bsz * num_heads, head_dim).transpose(0, 1)\n",
- " if key_padding_mask is not None:\n",
- " assert key_padding_mask.shape == (bsz, src_len), \\\n",
- " f\"expecting key_padding_mask shape of {(bsz, src_len)}, but got {key_padding_mask.shape}\"\n",
- " key_padding_mask = key_padding_mask.view(bsz, 1, 1, src_len). \\\n",
- " expand(-1, num_heads, -1, -1).reshape(bsz * num_heads, 1, src_len)\n",
- " if attn_mask is None:\n",
- " attn_mask = key_padding_mask\n",
- " elif attn_mask.dtype == torch.bool:\n",
- " attn_mask = attn_mask.logical_or(key_padding_mask)\n",
- " else:\n",
- " attn_mask = attn_mask.masked_fill(key_padding_mask, float(\"-inf\"))\n",
- " # 若attn_mask值是布尔值,则将mask转换为float\n",
- " if attn_mask is not None and attn_mask.dtype == torch.bool:\n",
- " new_attn_mask = torch.zeros_like(attn_mask, dtype=torch.float)\n",
- " new_attn_mask.masked_fill_(attn_mask, float(\"-inf\"))\n",
- " attn_mask = new_attn_mask\n",
- "\n",
- " # 若training为True时才应用dropout\n",
- " if not training:\n",
- " dropout_p = 0.0\n",
- " attn_output, attn_output_weights = _scaled_dot_product_attention(q, k, v, attn_mask, dropout_p)\n",
- " attn_output = attn_output.transpose(0, 1).contiguous().view(tgt_len, bsz, embed_dim)\n",
- " attn_output = nn.functional.linear(attn_output, out_proj_weight, out_proj_bias)\n",
- " if need_weights:\n",
- " # average attention weights over heads\n",
- " attn_output_weights = attn_output_weights.view(bsz, num_heads, tgt_len, src_len)\n",
- " return attn_output, attn_output_weights.sum(dim=1) / num_heads\n",
- " else:\n",
- " return attn_output, None"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "##### query, key, value通过_in_projection_packed变换得到q,k,v\n",
- "```\n",
- "q, k, v = _in_projection_packed(query, key, value, in_proj_weight, in_proj_bias)\n",
- "```\n",
- "\n",
- "对于`nn.functional.linear`函数,其实就是一个线性变换,与`nn.Linear`不同的是,前者可以提供权重矩阵和偏置,执行,而后者是可以自由决定输出的维度。"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 6,
- "metadata": {},
- "outputs": [],
- "source": [
- "def _in_projection_packed(\n",
- " q: Tensor,\n",
- " k: Tensor,\n",
- " v: Tensor,\n",
- " w: Tensor,\n",
- " b: Optional[Tensor] = None,\n",
- ") -> List[Tensor]:\n",
- " r\"\"\"\n",
- " 用一个大的权重参数矩阵进行线性变换\n",
- "\n",
- " 参数:\n",
- " q, k, v: 对自注意来说,三者都是src;对于seq2seq模型,k和v是一致的tensor。\n",
- " 但它们的最后一维(num_features或者叫做embed_dim)都必须保持一致。\n",
- " w: 用以线性变换的大矩阵,按照q,k,v的顺序压在一个tensor里面。\n",
- " b: 用以线性变换的偏置,按照q,k,v的顺序压在一个tensor里面。\n",
- "\n",
- " 形状:\n",
- " 输入:\n",
- " - q: shape:`(..., E)`,E是词嵌入的维度(下面出现的E均为此意)。\n",
- " - k: shape:`(..., E)`\n",
- " - v: shape:`(..., E)`\n",
- " - w: shape:`(E * 3, E)`\n",
- " - b: shape:`E * 3` \n",
- "\n",
- " 输出:\n",
- " - 输出列表 :`[q', k', v']`,q,k,v经过线性变换前后的形状都一致。\n",
- " \"\"\"\n",
- " E = q.size(-1)\n",
- " # 若为自注意,则q = k = v = src,因此它们的引用变量都是src\n",
- " # 即k is v和q is k结果均为True\n",
- " # 若为seq2seq,k = v,因而k is v的结果是True\n",
- " if k is v:\n",
- " if q is k:\n",
- " return F.linear(q, w, b).chunk(3, dim=-1)\n",
- " else:\n",
- " # seq2seq模型\n",
- " w_q, w_kv = w.split([E, E * 2])\n",
- " if b is None:\n",
- " b_q = b_kv = None\n",
- " else:\n",
- " b_q, b_kv = b.split([E, E * 2])\n",
- " return (F.linear(q, w_q, b_q),) + F.linear(k, w_kv, b_kv).chunk(2, dim=-1)\n",
- " else:\n",
- " w_q, w_k, w_v = w.chunk(3)\n",
- " if b is None:\n",
- " b_q = b_k = b_v = None\n",
- " else:\n",
- " b_q, b_k, b_v = b.chunk(3)\n",
- " return F.linear(q, w_q, b_q), F.linear(k, w_k, b_k), F.linear(v, w_v, b_v)\n",
- "\n",
- "# q, k, v = _in_projection_packed(query, key, value, in_proj_weight, in_proj_bias)"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "***\n",
- "\n",
- "##### 遮挡机制\n",
- "\n",
- "对于attn_mask来说,若为2D,形状如`(L, S)`,L和S分别代表着目标语言和源语言序列长度,若为3D,形状如`(N * num_heads, L, S)`,N代表着batch_size,num_heads代表注意力头的数目。若为attn_mask的dtype为ByteTensor,非0的位置会被忽略不做注意力;若为BoolTensor,True对应的位置会被忽略;若为数值,则会直接加到attn_weights。\n",
- "\n",
- "因为在decoder解码的时候,只能看该位置和它之前的,如果看后面就犯规了,所以需要attn_mask遮挡住。\n",
- "\n",
- "下面函数直接复制PyTorch的,意思是确保不同维度的mask形状正确以及不同类型的转换\n",
- "\n",
- "\n",
- "```python\n",
- "if attn_mask is not None:\n",
- " if attn_mask.dtype == torch.uint8:\n",
- " warnings.warn(\"Byte tensor for attn_mask in nn.MultiheadAttention is deprecated. Use bool tensor instead.\")\n",
- " attn_mask = attn_mask.to(torch.bool)\n",
- " else:\n",
- " assert attn_mask.is_floating_point() or attn_mask.dtype == torch.bool, \\\n",
- " f\"Only float, byte, and bool types are supported for attn_mask, not {attn_mask.dtype}\"\n",
- " # 对不同维度的形状判定\n",
- " if attn_mask.dim() == 2:\n",
- " correct_2d_size = (tgt_len, src_len)\n",
- " if attn_mask.shape != correct_2d_size:\n",
- " raise RuntimeError(f\"The shape of the 2D attn_mask is {attn_mask.shape}, but should be {correct_2d_size}.\")\n",
- " attn_mask = attn_mask.unsqueeze(0)\n",
- " elif attn_mask.dim() == 3:\n",
- " correct_3d_size = (bsz * num_heads, tgt_len, src_len)\n",
- " if attn_mask.shape != correct_3d_size:\n",
- " raise RuntimeError(f\"The shape of the 3D attn_mask is {attn_mask.shape}, but should be {correct_3d_size}.\")\n",
- " else:\n",
- " raise RuntimeError(f\"attn_mask's dimension {attn_mask.dim()} is not supported\")\n",
- "\n",
- "```\n",
- "与`attn_mask`不同的是,`key_padding_mask`是用来遮挡住key里面的值,详细来说应该是``,被忽略的情况与attn_mask一致。\n",
- "\n",
- "```python\n",
- "# 将key_padding_mask值改为布尔值\n",
- "if key_padding_mask is not None and key_padding_mask.dtype == torch.uint8:\n",
- " warnings.warn(\"Byte tensor for key_padding_mask in nn.MultiheadAttention is deprecated. Use bool tensor instead.\")\n",
- " key_padding_mask = key_padding_mask.to(torch.bool)\n",
- "```\n",
- "\n",
- "先介绍两个小函数,`logical_or`,输入两个tensor,并对这两个tensor里的值做`逻辑或`运算,只有当两个值均为0的时候才为`False`,其他时候均为`True`,另一个是`masked_fill`,输入是一个mask,和用以填充的值。mask由1,0组成,0的位置值维持不变,1的位置用新值填充。\n",
- "```python\n",
- "a = torch.tensor([0,1,10,0],dtype=torch.int8)\n",
- "b = torch.tensor([4,0,1,0],dtype=torch.int8)\n",
- "print(torch.logical_or(a,b))\n",
- "# tensor([ True, True, True, False])\n",
- "```\n",
- "\n",
- "```python\n",
- "r = torch.tensor([[0,0,0,0],[0,0,0,0]])\n",
- "mask = torch.tensor([[1,1,1,1],[0,0,0,0]])\n",
- "print(r.masked_fill(mask,1))\n",
- "# tensor([[1, 1, 1, 1],\n",
- "# [0, 0, 0, 0]])\n",
- "```\n",
- "其实attn_mask和key_padding_mask有些时候对象是一致的,所以有时候可以合起来看。`-inf`做softmax之后值为0,即被忽略。\n",
- "```python\n",
- "if key_padding_mask is not None:\n",
- " assert key_padding_mask.shape == (bsz, src_len), \\\n",
- " f\"expecting key_padding_mask shape of {(bsz, src_len)}, but got {key_padding_mask.shape}\"\n",
- " key_padding_mask = key_padding_mask.view(bsz, 1, 1, src_len). \\\n",
- " expand(-1, num_heads, -1, -1).reshape(bsz * num_heads, 1, src_len)\n",
- " # 若attn_mask为空,直接用key_padding_mask\n",
- " if attn_mask is None:\n",
- " attn_mask = key_padding_mask\n",
- " elif attn_mask.dtype == torch.bool:\n",
- " attn_mask = attn_mask.logical_or(key_padding_mask)\n",
- " else:\n",
- " attn_mask = attn_mask.masked_fill(key_padding_mask, float(\"-inf\"))\n",
- "\n",
- "# 若attn_mask值是布尔值,则将mask转换为float\n",
- "if attn_mask is not None and attn_mask.dtype == torch.bool:\n",
- " new_attn_mask = torch.zeros_like(attn_mask, dtype=torch.float)\n",
- " new_attn_mask.masked_fill_(attn_mask, float(\"-inf\"))\n",
- " attn_mask = new_attn_mask\n",
- "\n",
- "```"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "***\n",
- "##### 点积注意力"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 7,
- "metadata": {},
- "outputs": [],
- "source": [
- "from typing import Optional, Tuple, Any\n",
- "def _scaled_dot_product_attention(\n",
- " q: Tensor,\n",
- " k: Tensor,\n",
- " v: Tensor,\n",
- " attn_mask: Optional[Tensor] = None,\n",
- " dropout_p: float = 0.0,\n",
- ") -> Tuple[Tensor, Tensor]:\n",
- " r'''\n",
- " 在query, key, value上计算点积注意力,若有注意力遮盖则使用,并且应用一个概率为dropout_p的dropout\n",
- "\n",
- " 参数:\n",
- " - q: shape:`(B, Nt, E)` B代表batch size, Nt是目标语言序列长度,E是嵌入后的特征维度\n",
- " - key: shape:`(B, Ns, E)` Ns是源语言序列长度\n",
- " - value: shape:`(B, Ns, E)`与key形状一样\n",
- " - attn_mask: 要么是3D的tensor,形状为:`(B, Nt, Ns)`或者2D的tensor,形状如:`(Nt, Ns)`\n",
- "\n",
- " - Output: attention values: shape:`(B, Nt, E)`,与q的形状一致;attention weights: shape:`(B, Nt, Ns)`\n",
- " \n",
- " 例子:\n",
- " >>> q = torch.randn((2,3,6))\n",
- " >>> k = torch.randn((2,4,6))\n",
- " >>> v = torch.randn((2,4,6))\n",
- " >>> out = scaled_dot_product_attention(q, k, v)\n",
- " >>> out[0].shape, out[1].shape\n",
- " >>> torch.Size([2, 3, 6]) torch.Size([2, 3, 4])\n",
- " '''\n",
- " B, Nt, E = q.shape\n",
- " q = q / math.sqrt(E)\n",
- " # (B, Nt, E) x (B, E, Ns) -> (B, Nt, Ns)\n",
- " attn = torch.bmm(q, k.transpose(-2,-1))\n",
- " if attn_mask is not None:\n",
- " attn += attn_mask \n",
- " # attn意味着目标序列的每个词对源语言序列做注意力\n",
- " attn = F.softmax(attn, dim=-1)\n",
- " if dropout_p:\n",
- " attn = F.dropout(attn, p=dropout_p)\n",
- " # (B, Nt, Ns) x (B, Ns, E) -> (B, Nt, E)\n",
- " output = torch.bmm(attn, v)\n",
- " return output, attn \n"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "### 完整的多头注意力机制-MultiheadAttention"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 8,
- "metadata": {},
- "outputs": [],
- "source": [
- "class MultiheadAttention(nn.Module):\n",
- " r'''\n",
- " 参数:\n",
- " embed_dim: 词嵌入的维度\n",
- " num_heads: 平行头的数量\n",
- " batch_first: 若`True`,则为(batch, seq, feture),若为`False`,则为(seq, batch, feature)\n",
- " \n",
- " 例子:\n",
- " >>> multihead_attn = MultiheadAttention(embed_dim, num_heads)\n",
- " >>> attn_output, attn_output_weights = multihead_attn(query, key, value)\n",
- " '''\n",
- " def __init__(self, embed_dim, num_heads, dropout=0., bias=True,\n",
- " kdim=None, vdim=None, batch_first=False) -> None:\n",
- " # factory_kwargs = {'device': device, 'dtype': dtype}\n",
- " super(MultiheadAttention, self).__init__()\n",
- " self.embed_dim = embed_dim\n",
- " self.kdim = kdim if kdim is not None else embed_dim\n",
- " self.vdim = vdim if vdim is not None else embed_dim\n",
- " self._qkv_same_embed_dim = self.kdim == embed_dim and self.vdim == embed_dim\n",
- "\n",
- " self.num_heads = num_heads\n",
- " self.dropout = dropout\n",
- " self.batch_first = batch_first\n",
- " self.head_dim = embed_dim // num_heads\n",
- " assert self.head_dim * num_heads == self.embed_dim, \"embed_dim must be divisible by num_heads\"\n",
- "\n",
- " if self._qkv_same_embed_dim is False:\n",
- " self.q_proj_weight = Parameter(torch.empty((embed_dim, embed_dim)))\n",
- " self.k_proj_weight = Parameter(torch.empty((embed_dim, self.kdim)))\n",
- " self.v_proj_weight = Parameter(torch.empty((embed_dim, self.vdim)))\n",
- " self.register_parameter('in_proj_weight', None)\n",
- " else:\n",
- " self.in_proj_weight = Parameter(torch.empty((3 * embed_dim, embed_dim)))\n",
- " self.register_parameter('q_proj_weight', None)\n",
- " self.register_parameter('k_proj_weight', None)\n",
- " self.register_parameter('v_proj_weight', None)\n",
- "\n",
- " if bias:\n",
- " self.in_proj_bias = Parameter(torch.empty(3 * embed_dim))\n",
- " else:\n",
- " self.register_parameter('in_proj_bias', None)\n",
- " self.out_proj = nn.Linear(embed_dim, embed_dim, bias=bias)\n",
- "\n",
- " self._reset_parameters()\n",
- "\n",
- " def _reset_parameters(self):\n",
- " if self._qkv_same_embed_dim:\n",
- " xavier_uniform_(self.in_proj_weight)\n",
- " else:\n",
- " xavier_uniform_(self.q_proj_weight)\n",
- " xavier_uniform_(self.k_proj_weight)\n",
- " xavier_uniform_(self.v_proj_weight)\n",
- "\n",
- " if self.in_proj_bias is not None:\n",
- " constant_(self.in_proj_bias, 0.)\n",
- " constant_(self.out_proj.bias, 0.)\n",
- "\n",
- "\n",
- "\n",
- " def forward(self, query: Tensor, key: Tensor, value: Tensor, key_padding_mask: Optional[Tensor] = None,\n",
- " need_weights: bool = True, attn_mask: Optional[Tensor] = None) -> Tuple[Tensor, Optional[Tensor]]:\n",
- " if self.batch_first:\n",
- " query, key, value = [x.transpose(1, 0) for x in (query, key, value)]\n",
- "\n",
- " if not self._qkv_same_embed_dim:\n",
- " attn_output, attn_output_weights = multi_head_attention_forward(\n",
- " query, key, value, self.num_heads,\n",
- " self.in_proj_weight, self.in_proj_bias,\n",
- " self.dropout, self.out_proj.weight, self.out_proj.bias,\n",
- " training=self.training,\n",
- " key_padding_mask=key_padding_mask, need_weights=need_weights,\n",
- " attn_mask=attn_mask, use_separate_proj_weight=True,\n",
- " q_proj_weight=self.q_proj_weight, k_proj_weight=self.k_proj_weight,\n",
- " v_proj_weight=self.v_proj_weight)\n",
- " else:\n",
- " attn_output, attn_output_weights = multi_head_attention_forward(\n",
- " query, key, value, self.num_heads,\n",
- " self.in_proj_weight, self.in_proj_bias,\n",
- " self.dropout, self.out_proj.weight, self.out_proj.bias,\n",
- " training=self.training,\n",
- " key_padding_mask=key_padding_mask, need_weights=need_weights,\n",
- " attn_mask=attn_mask)\n",
- " if self.batch_first:\n",
- " return attn_output.transpose(1, 0), attn_output_weights\n",
- " else:\n",
- " return attn_output, attn_output_weights"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "\n",
- "接下来可以实践一下,并且把位置编码加起来,可以发现加入位置编码和进行多头注意力的前后形状都是不会变的"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 9,
- "metadata": {},
- "outputs": [
- {
- "name": "stdout",
- "output_type": "stream",
- "text": [
- "torch.Size([2, 4, 100])\n",
- "torch.Size([2, 4, 100]) torch.Size([4, 2, 2])\n"
- ]
- }
- ],
- "source": [
- "# 因为batch_first为False,所以src的shape:`(seq, batch, embed_dim)`\n",
- "src = torch.randn((2,4,100))\n",
- "src = positional_encoding(src,100,0.1)\n",
- "print(src.shape)\n",
- "multihead_attn = MultiheadAttention(100, 4, 0.1)\n",
- "attn_output, attn_output_weights = multihead_attn(src,src,src)\n",
- "print(attn_output.shape, attn_output_weights.shape)\n",
- "\n",
- "# torch.Size([2, 4, 100])\n",
- "# torch.Size([2, 4, 100]) torch.Size([4, 2, 2])"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "***\n",
- "## **搭建Transformer
**\n",
- "- Encoder Layer\n",
- "\n",
- ""
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 10,
- "metadata": {},
- "outputs": [],
- "source": [
- "class TransformerEncoderLayer(nn.Module):\n",
- " r'''\n",
- " 参数:\n",
- " d_model: 词嵌入的维度(必备)\n",
- " nhead: 多头注意力中平行头的数目(必备)\n",
- " dim_feedforward: 全连接层的神经元的数目,又称经过此层输入的维度(Default = 2048)\n",
- " dropout: dropout的概率(Default = 0.1)\n",
- " activation: 两个线性层中间的激活函数,默认relu或gelu\n",
- " lay_norm_eps: layer normalization中的微小量,防止分母为0(Default = 1e-5)\n",
- " batch_first: 若`True`,则为(batch, seq, feture),若为`False`,则为(seq, batch, feature)(Default:False)\n",
- "\n",
- " 例子:\n",
- " >>> encoder_layer = TransformerEncoderLayer(d_model=512, nhead=8)\n",
- " >>> src = torch.randn((32, 10, 512))\n",
- " >>> out = encoder_layer(src)\n",
- " '''\n",
- "\n",
- " def __init__(self, d_model, nhead, dim_feedforward=2048, dropout=0.1, activation=F.relu,\n",
- " layer_norm_eps=1e-5, batch_first=False) -> None:\n",
- " super(TransformerEncoderLayer, self).__init__()\n",
- " self.self_attn = MultiheadAttention(d_model, nhead, dropout=dropout, batch_first=batch_first)\n",
- " self.linear1 = nn.Linear(d_model, dim_feedforward)\n",
- " self.dropout = nn.Dropout(dropout)\n",
- " self.linear2 = nn.Linear(dim_feedforward, d_model)\n",
- "\n",
- " self.norm1 = nn.LayerNorm(d_model, eps=layer_norm_eps)\n",
- " self.norm2 = nn.LayerNorm(d_model, eps=layer_norm_eps)\n",
- " self.dropout1 = nn.Dropout(dropout)\n",
- " self.dropout2 = nn.Dropout(dropout)\n",
- " self.activation = activation \n",
- "\n",
- "\n",
- " def forward(self, src: Tensor, src_mask: Optional[Tensor] = None, src_key_padding_mask: Optional[Tensor] = None) -> Tensor:\n",
- " src = positional_encoding(src, src.shape[-1])\n",
- " src2 = self.self_attn(src, src, src, attn_mask=src_mask, \n",
- " key_padding_mask=src_key_padding_mask)[0]\n",
- " src = src + self.dropout1(src2)\n",
- " src = self.norm1(src)\n",
- " src2 = self.linear2(self.dropout(self.activation(self.linear1(src))))\n",
- " src = src + self.dropout(src2)\n",
- " src = self.norm2(src)\n",
- " return src\n"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 11,
- "metadata": {},
- "outputs": [
- {
- "name": "stdout",
- "output_type": "stream",
- "text": [
- "torch.Size([32, 10, 512])\n"
- ]
- }
- ],
- "source": [
- "# 用小例子看一下\n",
- "encoder_layer = TransformerEncoderLayer(d_model=512, nhead=8)\n",
- "src = torch.randn((32, 10, 512))\n",
- "out = encoder_layer(src)\n",
- "print(out.shape)\n",
- "# torch.Size([32, 10, 512])"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "### Transformer layer组成Encoder"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 12,
- "metadata": {},
- "outputs": [],
- "source": [
- "class TransformerEncoder(nn.Module):\n",
- " r'''\n",
- " 参数:\n",
- " encoder_layer(必备)\n",
- " num_layers: encoder_layer的层数(必备)\n",
- " norm: 归一化的选择(可选)\n",
- " \n",
- " 例子:\n",
- " >>> encoder_layer = TransformerEncoderLayer(d_model=512, nhead=8)\n",
- " >>> transformer_encoder = TransformerEncoder(encoder_layer, num_layers=6)\n",
- " >>> src = torch.randn((10, 32, 512))\n",
- " >>> out = transformer_encoder(src)\n",
- " '''\n",
- "\n",
- " def __init__(self, encoder_layer, num_layers, norm=None):\n",
- " super(TransformerEncoder, self).__init__()\n",
- " self.layer = encoder_layer\n",
- " self.num_layers = num_layers\n",
- " self.norm = norm\n",
- " \n",
- " def forward(self, src: Tensor, mask: Optional[Tensor] = None, src_key_padding_mask: Optional[Tensor] = None) -> Tensor:\n",
- " output = positional_encoding(src, src.shape[-1])\n",
- " for _ in range(self.num_layers):\n",
- " output = self.layer(output, src_mask=mask, src_key_padding_mask=src_key_padding_mask)\n",
- " \n",
- " if self.norm is not None:\n",
- " output = self.norm(output)\n",
- " \n",
- " return output"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 13,
- "metadata": {},
- "outputs": [
- {
- "name": "stdout",
- "output_type": "stream",
- "text": [
- "torch.Size([10, 32, 512])\n"
- ]
- }
- ],
- "source": [
- "# 例子\n",
- "encoder_layer = TransformerEncoderLayer(d_model=512, nhead=8)\n",
- "transformer_encoder = TransformerEncoder(encoder_layer, num_layers=6)\n",
- "src = torch.randn((10, 32, 512))\n",
- "out = transformer_encoder(src)\n",
- "print(out.shape)\n",
- "# torch.Size([10, 32, 512])"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "***\n",
- "## Decoder Layer:"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 14,
- "metadata": {},
- "outputs": [],
- "source": [
- "class TransformerDecoderLayer(nn.Module):\n",
- " r'''\n",
- " 参数:\n",
- " d_model: 词嵌入的维度(必备)\n",
- " nhead: 多头注意力中平行头的数目(必备)\n",
- " dim_feedforward: 全连接层的神经元的数目,又称经过此层输入的维度(Default = 2048)\n",
- " dropout: dropout的概率(Default = 0.1)\n",
- " activation: 两个线性层中间的激活函数,默认relu或gelu\n",
- " lay_norm_eps: layer normalization中的微小量,防止分母为0(Default = 1e-5)\n",
- " batch_first: 若`True`,则为(batch, seq, feture),若为`False`,则为(seq, batch, feature)(Default:False)\n",
- " \n",
- " 例子:\n",
- " >>> decoder_layer = TransformerDecoderLayer(d_model=512, nhead=8)\n",
- " >>> memory = torch.randn((10, 32, 512))\n",
- " >>> tgt = torch.randn((20, 32, 512))\n",
- " >>> out = decoder_layer(tgt, memory)\n",
- " '''\n",
- " def __init__(self, d_model, nhead, dim_feedforward=2048, dropout=0.1, activation=F.relu,\n",
- " layer_norm_eps=1e-5, batch_first=False) -> None:\n",
- " super(TransformerDecoderLayer, self).__init__()\n",
- " self.self_attn = MultiheadAttention(d_model, nhead, dropout=dropout, batch_first=batch_first)\n",
- " self.multihead_attn = MultiheadAttention(d_model, nhead, dropout=dropout, batch_first=batch_first)\n",
- "\n",
- " self.linear1 = nn.Linear(d_model, dim_feedforward)\n",
- " self.dropout = nn.Dropout(dropout)\n",
- " self.linear2 = nn.Linear(dim_feedforward, d_model)\n",
- "\n",
- " self.norm1 = nn.LayerNorm(d_model, eps=layer_norm_eps)\n",
- " self.norm2 = nn.LayerNorm(d_model, eps=layer_norm_eps)\n",
- " self.norm3 = nn.LayerNorm(d_model, eps=layer_norm_eps)\n",
- " self.dropout1 = nn.Dropout(dropout)\n",
- " self.dropout2 = nn.Dropout(dropout)\n",
- " self.dropout3 = nn.Dropout(dropout)\n",
- "\n",
- " self.activation = activation\n",
- "\n",
- " def forward(self, tgt: Tensor, memory: Tensor, tgt_mask: Optional[Tensor] = None, \n",
- " memory_mask: Optional[Tensor] = None,tgt_key_padding_mask: Optional[Tensor] = None, memory_key_padding_mask: Optional[Tensor] = None) -> Tensor:\n",
- " r'''\n",
- " 参数:\n",
- " tgt: 目标语言序列(必备)\n",
- " memory: 从最后一个encoder_layer跑出的句子(必备)\n",
- " tgt_mask: 目标语言序列的mask(可选)\n",
- " memory_mask(可选)\n",
- " tgt_key_padding_mask(可选)\n",
- " memory_key_padding_mask(可选)\n",
- " '''\n",
- " tgt2 = self.self_attn(tgt, tgt, tgt, attn_mask=tgt_mask,\n",
- " key_padding_mask=tgt_key_padding_mask)[0]\n",
- " tgt = tgt + self.dropout1(tgt2)\n",
- " tgt = self.norm1(tgt)\n",
- " tgt2 = self.multihead_attn(tgt, memory, memory, attn_mask=memory_mask,\n",
- " key_padding_mask=memory_key_padding_mask)[0]\n",
- " tgt = tgt + self.dropout2(tgt2)\n",
- " tgt = self.norm2(tgt)\n",
- " tgt2 = self.linear2(self.dropout(self.activation(self.linear1(tgt))))\n",
- " tgt = tgt + self.dropout3(tgt2)\n",
- " tgt = self.norm3(tgt)\n",
- " return tgt"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 15,
- "metadata": {},
- "outputs": [
- {
- "name": "stdout",
- "output_type": "stream",
- "text": [
- "torch.Size([20, 32, 512])\n"
- ]
- }
- ],
- "source": [
- "# 可爱的小例子\n",
- "decoder_layer = nn.TransformerDecoderLayer(d_model=512, nhead=8)\n",
- "memory = torch.randn((10, 32, 512))\n",
- "tgt = torch.randn((20, 32, 512))\n",
- "out = decoder_layer(tgt, memory)\n",
- "print(out.shape)\n",
- "# torch.Size([20, 32, 512])"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 16,
- "metadata": {},
- "outputs": [],
- "source": [
- "## Decoder"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 17,
- "metadata": {},
- "outputs": [],
- "source": [
- "class TransformerDecoder(nn.Module):\n",
- " r'''\n",
- " 参数:\n",
- " decoder_layer(必备)\n",
- " num_layers: decoder_layer的层数(必备)\n",
- " norm: 归一化选择\n",
- " \n",
- " 例子:\n",
- " >>> decoder_layer =TransformerDecoderLayer(d_model=512, nhead=8)\n",
- " >>> transformer_decoder = TransformerDecoder(decoder_layer, num_layers=6)\n",
- " >>> memory = torch.rand(10, 32, 512)\n",
- " >>> tgt = torch.rand(20, 32, 512)\n",
- " >>> out = transformer_decoder(tgt, memory)\n",
- " '''\n",
- " def __init__(self, decoder_layer, num_layers, norm=None):\n",
- " super(TransformerDecoder, self).__init__()\n",
- " self.layer = decoder_layer\n",
- " self.num_layers = num_layers\n",
- " self.norm = norm\n",
- " \n",
- " def forward(self, tgt: Tensor, memory: Tensor, tgt_mask: Optional[Tensor] = None,\n",
- " memory_mask: Optional[Tensor] = None, tgt_key_padding_mask: Optional[Tensor] = None,\n",
- " memory_key_padding_mask: Optional[Tensor] = None) -> Tensor:\n",
- " output = tgt\n",
- " for _ in range(self.num_layers):\n",
- " output = self.layer(output, memory, tgt_mask=tgt_mask,\n",
- " memory_mask=memory_mask,\n",
- " tgt_key_padding_mask=tgt_key_padding_mask,\n",
- " memory_key_padding_mask=memory_key_padding_mask)\n",
- " if self.norm is not None:\n",
- " output = self.norm(output)\n",
- "\n",
- " return output"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 18,
- "metadata": {},
- "outputs": [
- {
- "name": "stdout",
- "output_type": "stream",
- "text": [
- "torch.Size([20, 32, 512])\n"
- ]
- }
- ],
- "source": [
- "# 可爱的小例子\n",
- "decoder_layer =TransformerDecoderLayer(d_model=512, nhead=8)\n",
- "transformer_decoder = TransformerDecoder(decoder_layer, num_layers=6)\n",
- "memory = torch.rand(10, 32, 512)\n",
- "tgt = torch.rand(20, 32, 512)\n",
- "out = transformer_decoder(tgt, memory)\n",
- "print(out.shape)\n",
- "# torch.Size([20, 32, 512])"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "总结一下,其实经过位置编码,多头注意力,Encoder Layer和Decoder Layer形状不会变的,而Encoder和Decoder分别与src和tgt形状一致"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "## Transformer"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 19,
- "metadata": {},
- "outputs": [],
- "source": [
- "class Transformer(nn.Module):\n",
- " r'''\n",
- " 参数:\n",
- " d_model: 词嵌入的维度(必备)(Default=512)\n",
- " nhead: 多头注意力中平行头的数目(必备)(Default=8)\n",
- " num_encoder_layers:编码层层数(Default=8)\n",
- " num_decoder_layers:解码层层数(Default=8)\n",
- " dim_feedforward: 全连接层的神经元的数目,又称经过此层输入的维度(Default = 2048)\n",
- " dropout: dropout的概率(Default = 0.1)\n",
- " activation: 两个线性层中间的激活函数,默认relu或gelu\n",
- " custom_encoder: 自定义encoder(Default=None)\n",
- " custom_decoder: 自定义decoder(Default=None)\n",
- " lay_norm_eps: layer normalization中的微小量,防止分母为0(Default = 1e-5)\n",
- " batch_first: 若`True`,则为(batch, seq, feture),若为`False`,则为(seq, batch, feature)(Default:False)\n",
- " \n",
- " 例子:\n",
- " >>> transformer_model = Transformer(nhead=16, num_encoder_layers=12)\n",
- " >>> src = torch.rand((10, 32, 512))\n",
- " >>> tgt = torch.rand((20, 32, 512))\n",
- " >>> out = transformer_model(src, tgt)\n",
- " '''\n",
- " def __init__(self, d_model: int = 512, nhead: int = 8, num_encoder_layers: int = 6,\n",
- " num_decoder_layers: int = 6, dim_feedforward: int = 2048, dropout: float = 0.1,\n",
- " activation = F.relu, custom_encoder: Optional[Any] = None, custom_decoder: Optional[Any] = None,\n",
- " layer_norm_eps: float = 1e-5, batch_first: bool = False) -> None:\n",
- " super(Transformer, self).__init__()\n",
- " if custom_encoder is not None:\n",
- " self.encoder = custom_encoder\n",
- " else:\n",
- " encoder_layer = TransformerEncoderLayer(d_model, nhead, dim_feedforward, dropout,\n",
- " activation, layer_norm_eps, batch_first)\n",
- " encoder_norm = nn.LayerNorm(d_model, eps=layer_norm_eps)\n",
- " self.encoder = TransformerEncoder(encoder_layer, num_encoder_layers)\n",
- "\n",
- " if custom_decoder is not None:\n",
- " self.decoder = custom_decoder\n",
- " else:\n",
- " decoder_layer = TransformerDecoderLayer(d_model, nhead, dim_feedforward, dropout,\n",
- " activation, layer_norm_eps, batch_first)\n",
- " decoder_norm = nn.LayerNorm(d_model, eps=layer_norm_eps)\n",
- " self.decoder = TransformerDecoder(decoder_layer, num_decoder_layers, decoder_norm)\n",
- "\n",
- " self._reset_parameters()\n",
- "\n",
- " self.d_model = d_model\n",
- " self.nhead = nhead\n",
- "\n",
- " self.batch_first = batch_first\n",
- "\n",
- " def forward(self, src: Tensor, tgt: Tensor, src_mask: Optional[Tensor] = None, tgt_mask: Optional[Tensor] = None,\n",
- " memory_mask: Optional[Tensor] = None, src_key_padding_mask: Optional[Tensor] = None,\n",
- " tgt_key_padding_mask: Optional[Tensor] = None, memory_key_padding_mask: Optional[Tensor] = None) -> Tensor:\n",
- " r'''\n",
- " 参数:\n",
- " src: 源语言序列(送入Encoder)(必备)\n",
- " tgt: 目标语言序列(送入Decoder)(必备)\n",
- " src_mask: (可选)\n",
- " tgt_mask: (可选)\n",
- " memory_mask: (可选)\n",
- " src_key_padding_mask: (可选)\n",
- " tgt_key_padding_mask: (可选)\n",
- " memory_key_padding_mask: (可选)\n",
- " \n",
- " 形状:\n",
- " - src: shape:`(S, N, E)`, `(N, S, E)` if batch_first.\n",
- " - tgt: shape:`(T, N, E)`, `(N, T, E)` if batch_first.\n",
- " - src_mask: shape:`(S, S)`.\n",
- " - tgt_mask: shape:`(T, T)`.\n",
- " - memory_mask: shape:`(T, S)`.\n",
- " - src_key_padding_mask: shape:`(N, S)`.\n",
- " - tgt_key_padding_mask: shape:`(N, T)`.\n",
- " - memory_key_padding_mask: shape:`(N, S)`.\n",
- "\n",
- " [src/tgt/memory]_mask确保有些位置不被看到,如做decode的时候,只能看该位置及其以前的,而不能看后面的。\n",
- " 若为ByteTensor,非0的位置会被忽略不做注意力;若为BoolTensor,True对应的位置会被忽略;\n",
- " 若为数值,则会直接加到attn_weights\n",
- "\n",
- " [src/tgt/memory]_key_padding_mask 使得key里面的某些元素不参与attention计算,三种情况同上\n",
- "\n",
- " - output: shape:`(T, N, E)`, `(N, T, E)` if batch_first.\n",
- "\n",
- " 注意:\n",
- " src和tgt的最后一维需要等于d_model,batch的那一维需要相等\n",
- " \n",
- " 例子:\n",
- " >>> output = transformer_model(src, tgt, src_mask=src_mask, tgt_mask=tgt_mask)\n",
- " '''\n",
- " memory = self.encoder(src, mask=src_mask, src_key_padding_mask=src_key_padding_mask)\n",
- " output = self.decoder(tgt, memory, tgt_mask=tgt_mask, memory_mask=memory_mask,\n",
- " tgt_key_padding_mask=tgt_key_padding_mask,\n",
- " memory_key_padding_mask=memory_key_padding_mask)\n",
- " return output\n",
- " \n",
- " def generate_square_subsequent_mask(self, sz: int) -> Tensor:\n",
- " r'''产生关于序列的mask,被遮住的区域赋值`-inf`,未被遮住的区域赋值为`0`'''\n",
- " mask = (torch.triu(torch.ones(sz, sz)) == 1).transpose(0, 1)\n",
- " mask = mask.float().masked_fill(mask == 0, float('-inf')).masked_fill(mask == 1, float(0.0))\n",
- " return mask\n",
- "\n",
- " def _reset_parameters(self):\n",
- " r'''用正态分布初始化参数'''\n",
- " for p in self.parameters():\n",
- " if p.dim() > 1:\n",
- " xavier_uniform_(p)"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 20,
- "metadata": {},
- "outputs": [
- {
- "name": "stdout",
- "output_type": "stream",
- "text": [
- "torch.Size([20, 32, 512])\n"
- ]
- }
- ],
- "source": [
- "# 小例子\n",
- "transformer_model = Transformer(nhead=16, num_encoder_layers=12)\n",
- "src = torch.rand((10, 32, 512))\n",
- "tgt = torch.rand((20, 32, 512))\n",
- "out = transformer_model(src, tgt)\n",
- "print(out.shape)\n",
- "# torch.Size([20, 32, 512])"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "到此为止,PyTorch的Transformer库我们已经全部实现,相比于官方的版本,手写的这个少了较多的判定语句。\n",
- "## 致谢\n",
- "本文由台运鹏撰写,本项目成员重新组织和整理。最后,期待您的阅读反馈和star,谢谢。"
- ]
- }
- ],
- "metadata": {
- "interpreter": {
- "hash": "3bfce0b4c492a35815b5705a19fe374a7eea0baaa08b34d90450caf1fe9ce20b"
- },
- "kernelspec": {
- "display_name": "Python 3.8.10 64-bit ('venv': virtualenv)",
- "name": "python3"
- },
- "language_info": {
- "name": "python",
- "version": ""
- },
- "orig_nbformat": 4
- },
- "nbformat": 4,
- "nbformat_minor": 2
-}
\ No newline at end of file
diff --git a/docs/篇章2-Transformer相关原理/2.2.1-Pytorch编写完整的Transformer.md b/docs/篇章2-Transformer相关原理/2.2.1-Pytorch编写完整的Transformer.md
deleted file mode 100644
index 7ffcad7..0000000
--- a/docs/篇章2-Transformer相关原理/2.2.1-Pytorch编写完整的Transformer.md
+++ /dev/null
@@ -1,923 +0,0 @@
-# Pytorch编写完整的Transformer
-本文涉及的jupter notebook在[Pytorch编写完整的Transformer](https://github.com/datawhalechina/learn-nlp-with-transformers/blob/main/docs/%E7%AF%87%E7%AB%A02-Transformer%E7%9B%B8%E5%85%B3%E5%8E%9F%E7%90%86/2.2.1-Pytorch%E7%BC%96%E5%86%99%E5%AE%8C%E6%95%B4%E7%9A%84Transformer.ipynb)
-在阅读完[2.2-图解transformer](./篇章2-Transformer相关原理/2.2-图解transformer.md)之后,希望大家能对transformer各个模块的设计和计算有一个形象的认识,本小节我们基于pytorch来实现一个Transformer,帮助大家进一步学习这个复杂的模型。
-**章节**
-
-- [词嵌入](#embed)
-- [位置编码](#pos)
-- [多头注意力](#multihead)
-- [搭建Transformer](#build)
-
-
-
-图:Transformer结构图
-
-## **词嵌入
**
-
-如上图所示,Transformer图里左边的是Encoder,右边是Decoder部分。Encoder输入源语言序列,Decoder里面输入需要被翻译的语言文本(在训练时)。一个文本常有许多序列组成,常见操作为将序列进行一些预处理(如词切分等)变成列表,一个序列的列表的元素通常为词表中不可切分的最小词,整个文本就是一个大列表,元素为一个一个由序列组成的列表。如一个序列经过切分后变为["am", "##ro", "##zi", "meets", "his", "father"],接下来按照它们在词表中对应的索引进行转换,假设结果如[23, 94, 13, 41, 27, 96]。假如整个文本一共100个句子,那么就有100个列表为它的元素,因为每个序列的长度不一,需要设定最大长度,这里不妨设为128,那么将整个文本转换为数组之后,形状即为100 x 128,这就对应着batch_size和seq_length。
-
-输入之后,紧接着进行词嵌入处理,词嵌入就是将每一个词用预先训练好的向量进行映射。
-
-词嵌入在torch里基于`torch.nn.Embedding`实现,实例化时需要设置的参数为词表的大小和被映射的向量的维度比如`embed = nn.Embedding(10,8)`。向量的维度通俗来说就是向量里面有多少个数。注意,第一个参数是词表的大小,如果你目前最多有8个词,通常填写10(多一个位置留给unk和pad),你后面万一进入与这8个词不同的词就映射到unk上,序列padding的部分就映射到pad上。
-
-假如我们打算映射到8维(num_features或者embed_dim),那么,整个文本的形状变为100 x 128 x 8。接下来举个小例子解释一下:假设我们词表一共有10个词(算上unk和pad),文本里有2个句子,每个句子有4个词,我们想要把每个词映射到8维的向量。于是2,4,8对应于batch_size, seq_length, embed_dim(如果batch在第一维的话)。
-
-另外,一般深度学习任务只改变num_features,所以讲维度一般是针对最后特征所在的维度。
-
-开始编程:
-
-所有需要的包的导入:
-```python
-import torch
-import torch.nn as nn
-from torch.nn.parameter import Parameter
-from torch.nn.init import xavier_uniform_
-from torch.nn.init import constant_
-from torch.nn.init import xavier_normal_
-import torch.nn.functional as F
-from typing import Optional, Tuple, Any
-from typing import List, Optional, Tuple
-import math
-import warnings
-```
-```python
-X = torch.zeros((2,4),dtype=torch.long)
-embed = nn.Embedding(10,8)
-print(embed(X).shape)
-```
-
-
-## **位置编码
**
-
-词嵌入之后紧接着就是位置编码,位置编码用以区分不同词以及同词不同特征之间的关系。代码中需要注意:X_只是初始化的矩阵,并不是输入进来的;完成位置编码之后会加一个dropout。另外,位置编码是最后加上去的,因此输入输出形状不变。
-
-
-
-```python
-Tensor = torch.Tensor
-def positional_encoding(X, num_features, dropout_p=0.1, max_len=512) -> Tensor:
- r'''
- 给输入加入位置编码
- 参数:
- - num_features: 输入进来的维度
- - dropout_p: dropout的概率,当其为非零时执行dropout
- - max_len: 句子的最大长度,默认512
-
- 形状:
- - 输入: [batch_size, seq_length, num_features]
- - 输出: [batch_size, seq_length, num_features]
-
- 例子:
- >>> X = torch.randn((2,4,10))
- >>> X = positional_encoding(X, 10)
- >>> print(X.shape)
- >>> torch.Size([2, 4, 10])
- '''
-
- dropout = nn.Dropout(dropout_p)
- P = torch.zeros((1,max_len,num_features))
- X_ = torch.arange(max_len,dtype=torch.float32).reshape(-1,1) / torch.pow(
- 10000,
- torch.arange(0,num_features,2,dtype=torch.float32) /num_features)
- P[:,:,0::2] = torch.sin(X_)
- P[:,:,1::2] = torch.cos(X_)
- X = X + P[:,:X.shape[1],:].to(X.device)
- return dropout(X)
-```
-
-
-```python
-# 位置编码例子
-X = torch.randn((2,4,10))
-X = positional_encoding(X, 10)
-print(X.shape)
-```
-
-
-## **多头注意力机制
**
-
-### 拆开看多头注意力机制
-**完整版本可运行的多头注意里机制的class在后面,[完整的多头注意力机制-MultiheadAttentionion](#mha) 再回来依次看下面的解释。**
-
-多头注意力类主要成分是:参数初始化、multi_head_attention_forward
-
-#### 初始化参数
-```python
-if self._qkv_same_embed_dim is False:
- # 初始化前后形状维持不变
- # (seq_length x embed_dim) x (embed_dim x embed_dim) ==> (seq_length x embed_dim)
- self.q_proj_weight = Parameter(torch.empty((embed_dim, embed_dim)))
- self.k_proj_weight = Parameter(torch.empty((embed_dim, self.kdim)))
- self.v_proj_weight = Parameter(torch.empty((embed_dim, self.vdim)))
- self.register_parameter('in_proj_weight', None)
-else:
- self.in_proj_weight = Parameter(torch.empty((3 * embed_dim, embed_dim)))
- self.register_parameter('q_proj_weight', None)
- self.register_parameter('k_proj_weight', None)
- self.register_parameter('v_proj_weight', None)
-
-if bias:
- self.in_proj_bias = Parameter(torch.empty(3 * embed_dim))
-else:
- self.register_parameter('in_proj_bias', None)
-# 后期会将所有头的注意力拼接在一起然后乘上权重矩阵输出
-# out_proj是为了后期准备的
-self.out_proj = nn.Linear(embed_dim, embed_dim, bias=bias)
-self._reset_parameters()
-```
-
-torch.empty是按照所给的形状形成对应的tensor,特点是填充的值还未初始化,类比torch.randn(标准正态分布),这就是一种初始化的方式。在PyTorch中,变量类型是tensor的话是无法修改值的,而Parameter()函数可以看作为一种类型转变函数,将不可改值的tensor转换为可训练可修改的模型参数,即与model.parameters绑定在一起,register_parameter的意思是是否将这个参数放到model.parameters,None的意思是没有这个参数。
-
-这里有个if判断,用以判断q,k,v的最后一维是否一致,若一致,则一个大的权重矩阵全部乘然后分割出来,若不是,则各初始化各的,其实初始化是不会改变原来的形状的(如,见注释)。
-
-可以发现最后有一个_reset_parameters()函数,这个是用来初始化参数数值的。xavier_uniform意思是从[连续型均匀分布](https://zh.wikipedia.org/wiki/%E9%80%A3%E7%BA%8C%E5%9E%8B%E5%9D%87%E5%8B%BB%E5%88%86%E5%B8%83)里面随机取样出值来作为初始化的值,xavier_normal_取样的分布是正态分布。正因为初始化值在训练神经网络的时候很重要,所以才需要这两个函数。
-
-constant_意思是用所给值来填充输入的向量。
-
-另外,在PyTorch的源码里,似乎projection代表是一种线性变换的意思,in_proj_bias的意思就是一开始的线性变换的偏置
-
-```python
-def _reset_parameters(self):
- if self._qkv_same_embed_dim:
- xavier_uniform_(self.in_proj_weight)
- else:
- xavier_uniform_(self.q_proj_weight)
- xavier_uniform_(self.k_proj_weight)
- xavier_uniform_(self.v_proj_weight)
- if self.in_proj_bias is not None:
- constant_(self.in_proj_bias, 0.)
- constant_(self.out_proj.bias, 0.)
-
-```
-
-#### multi_head_attention_forward
-这个函数如下代码所示,主要分成3个部分:
-- query, key, value通过_in_projection_packed变换得到q,k,v
-- 遮挡机制
-- 点积注意力
-
-
-```python
-import torch
-Tensor = torch.Tensor
-def multi_head_attention_forward(
- query: Tensor,
- key: Tensor,
- value: Tensor,
- num_heads: int,
- in_proj_weight: Tensor,
- in_proj_bias: Optional[Tensor],
- dropout_p: float,
- out_proj_weight: Tensor,
- out_proj_bias: Optional[Tensor],
- training: bool = True,
- key_padding_mask: Optional[Tensor] = None,
- need_weights: bool = True,
- attn_mask: Optional[Tensor] = None,
- use_seperate_proj_weight = None,
- q_proj_weight: Optional[Tensor] = None,
- k_proj_weight: Optional[Tensor] = None,
- v_proj_weight: Optional[Tensor] = None,
-) -> Tuple[Tensor, Optional[Tensor]]:
- r'''
- 形状:
- 输入:
- - query:`(L, N, E)`
- - key: `(S, N, E)`
- - value: `(S, N, E)`
- - key_padding_mask: `(N, S)`
- - attn_mask: `(L, S)` or `(N * num_heads, L, S)`
- 输出:
- - attn_output:`(L, N, E)`
- - attn_output_weights:`(N, L, S)`
- '''
- tgt_len, bsz, embed_dim = query.shape
- src_len, _, _ = key.shape
- head_dim = embed_dim // num_heads
- q, k, v = _in_projection_packed(query, key, value, in_proj_weight, in_proj_bias)
-
- if attn_mask is not None:
- if attn_mask.dtype == torch.uint8:
- warnings.warn("Byte tensor for attn_mask in nn.MultiheadAttention is deprecated. Use bool tensor instead.")
- attn_mask = attn_mask.to(torch.bool)
- else:
- assert attn_mask.is_floating_point() or attn_mask.dtype == torch.bool, \
- f"Only float, byte, and bool types are supported for attn_mask, not {attn_mask.dtype}"
-
- if attn_mask.dim() == 2:
- correct_2d_size = (tgt_len, src_len)
- if attn_mask.shape != correct_2d_size:
- raise RuntimeError(f"The shape of the 2D attn_mask is {attn_mask.shape}, but should be {correct_2d_size}.")
- attn_mask = attn_mask.unsqueeze(0)
- elif attn_mask.dim() == 3:
- correct_3d_size = (bsz * num_heads, tgt_len, src_len)
- if attn_mask.shape != correct_3d_size:
- raise RuntimeError(f"The shape of the 3D attn_mask is {attn_mask.shape}, but should be {correct_3d_size}.")
- else:
- raise RuntimeError(f"attn_mask's dimension {attn_mask.dim()} is not supported")
-
- if key_padding_mask is not None and key_padding_mask.dtype == torch.uint8:
- warnings.warn("Byte tensor for key_padding_mask in nn.MultiheadAttention is deprecated. Use bool tensor instead.")
- key_padding_mask = key_padding_mask.to(torch.bool)
-
- # reshape q,k,v将Batch放在第一维以适合点积注意力
- # 同时为多头机制,将不同的头拼在一起组成一层
- q = q.contiguous().view(tgt_len, bsz * num_heads, head_dim).transpose(0, 1)
- k = k.contiguous().view(-1, bsz * num_heads, head_dim).transpose(0, 1)
- v = v.contiguous().view(-1, bsz * num_heads, head_dim).transpose(0, 1)
- if key_padding_mask is not None:
- assert key_padding_mask.shape == (bsz, src_len), \
- f"expecting key_padding_mask shape of {(bsz, src_len)}, but got {key_padding_mask.shape}"
- key_padding_mask = key_padding_mask.view(bsz, 1, 1, src_len). \
- expand(-1, num_heads, -1, -1).reshape(bsz * num_heads, 1, src_len)
- if attn_mask is None:
- attn_mask = key_padding_mask
- elif attn_mask.dtype == torch.bool:
- attn_mask = attn_mask.logical_or(key_padding_mask)
- else:
- attn_mask = attn_mask.masked_fill(key_padding_mask, float("-inf"))
- # 若attn_mask值是布尔值,则将mask转换为float
- if attn_mask is not None and attn_mask.dtype == torch.bool:
- new_attn_mask = torch.zeros_like(attn_mask, dtype=torch.float)
- new_attn_mask.masked_fill_(attn_mask, float("-inf"))
- attn_mask = new_attn_mask
-
- # 若training为True时才应用dropout
- if not training:
- dropout_p = 0.0
- attn_output, attn_output_weights = _scaled_dot_product_attention(q, k, v, attn_mask, dropout_p)
- attn_output = attn_output.transpose(0, 1).contiguous().view(tgt_len, bsz, embed_dim)
- attn_output = nn.functional.linear(attn_output, out_proj_weight, out_proj_bias)
- if need_weights:
- # average attention weights over heads
- attn_output_weights = attn_output_weights.view(bsz, num_heads, tgt_len, src_len)
- return attn_output, attn_output_weights.sum(dim=1) / num_heads
- else:
- return attn_output, None
-```
-
-##### query, key, value通过_in_projection_packed变换得到q,k,v
-```
-q, k, v = _in_projection_packed(query, key, value, in_proj_weight, in_proj_bias)
-```
-
-对于`nn.functional.linear`函数,其实就是一个线性变换,与`nn.Linear`不同的是,前者可以提供权重矩阵和偏置,执行,而后者是可以自由决定输出的维度。
-
-
-```python
-def _in_projection_packed(
- q: Tensor,
- k: Tensor,
- v: Tensor,
- w: Tensor,
- b: Optional[Tensor] = None,
-) -> List[Tensor]:
- r"""
- 用一个大的权重参数矩阵进行线性变换
-
- 参数:
- q, k, v: 对自注意来说,三者都是src;对于seq2seq模型,k和v是一致的tensor。
- 但它们的最后一维(num_features或者叫做embed_dim)都必须保持一致。
- w: 用以线性变换的大矩阵,按照q,k,v的顺序压在一个tensor里面。
- b: 用以线性变换的偏置,按照q,k,v的顺序压在一个tensor里面。
-
- 形状:
- 输入:
- - q: shape:`(..., E)`,E是词嵌入的维度(下面出现的E均为此意)。
- - k: shape:`(..., E)`
- - v: shape:`(..., E)`
- - w: shape:`(E * 3, E)`
- - b: shape:`E * 3`
-
- 输出:
- - 输出列表 :`[q', k', v']`,q,k,v经过线性变换前后的形状都一致。
- """
- E = q.size(-1)
- # 若为自注意,则q = k = v = src,因此它们的引用变量都是src
- # 即k is v和q is k结果均为True
- # 若为seq2seq,k = v,因而k is v的结果是True
- if k is v:
- if q is k:
- return F.linear(q, w, b).chunk(3, dim=-1)
- else:
- # seq2seq模型
- w_q, w_kv = w.split([E, E * 2])
- if b is None:
- b_q = b_kv = None
- else:
- b_q, b_kv = b.split([E, E * 2])
- return (F.linear(q, w_q, b_q),) + F.linear(k, w_kv, b_kv).chunk(2, dim=-1)
- else:
- w_q, w_k, w_v = w.chunk(3)
- if b is None:
- b_q = b_k = b_v = None
- else:
- b_q, b_k, b_v = b.chunk(3)
- return F.linear(q, w_q, b_q), F.linear(k, w_k, b_k), F.linear(v, w_v, b_v)
-
-# q, k, v = _in_projection_packed(query, key, value, in_proj_weight, in_proj_bias)
-```
-
-***
-
-##### 遮挡机制
-
-对于attn_mask来说,若为2D,形状如`(L, S)`,L和S分别代表着目标语言和源语言序列长度,若为3D,形状如`(N * num_heads, L, S)`,N代表着batch_size,num_heads代表注意力头的数目。若为attn_mask的dtype为ByteTensor,非0的位置会被忽略不做注意力;若为BoolTensor,True对应的位置会被忽略;若为数值,则会直接加到attn_weights。
-
-因为在decoder解码的时候,只能看该位置和它之前的,如果看后面就犯规了,所以需要attn_mask遮挡住。
-
-下面函数直接复制PyTorch的,意思是确保不同维度的mask形状正确以及不同类型的转换
-
-
-```python
-if attn_mask is not None:
- if attn_mask.dtype == torch.uint8:
- warnings.warn("Byte tensor for attn_mask in nn.MultiheadAttention is deprecated. Use bool tensor instead.")
- attn_mask = attn_mask.to(torch.bool)
- else:
- assert attn_mask.is_floating_point() or attn_mask.dtype == torch.bool, \
- f"Only float, byte, and bool types are supported for attn_mask, not {attn_mask.dtype}"
- # 对不同维度的形状判定
- if attn_mask.dim() == 2:
- correct_2d_size = (tgt_len, src_len)
- if attn_mask.shape != correct_2d_size:
- raise RuntimeError(f"The shape of the 2D attn_mask is {attn_mask.shape}, but should be {correct_2d_size}.")
- attn_mask = attn_mask.unsqueeze(0)
- elif attn_mask.dim() == 3:
- correct_3d_size = (bsz * num_heads, tgt_len, src_len)
- if attn_mask.shape != correct_3d_size:
- raise RuntimeError(f"The shape of the 3D attn_mask is {attn_mask.shape}, but should be {correct_3d_size}.")
- else:
- raise RuntimeError(f"attn_mask's dimension {attn_mask.dim()} is not supported")
-
-```
-与`attn_mask`不同的是,`key_padding_mask`是用来遮挡住key里面的值,详细来说应该是``,被忽略的情况与attn_mask一致。
-
-```python
-# 将key_padding_mask值改为布尔值
-if key_padding_mask is not None and key_padding_mask.dtype == torch.uint8:
- warnings.warn("Byte tensor for key_padding_mask in nn.MultiheadAttention is deprecated. Use bool tensor instead.")
- key_padding_mask = key_padding_mask.to(torch.bool)
-```
-
-先介绍两个小函数,`logical_or`,输入两个tensor,并对这两个tensor里的值做`逻辑或`运算,只有当两个值均为0的时候才为`False`,其他时候均为`True`,另一个是`masked_fill`,输入是一个mask,和用以填充的值。mask由1,0组成,0的位置值维持不变,1的位置用新值填充。
-```python
-a = torch.tensor([0,1,10,0],dtype=torch.int8)
-b = torch.tensor([4,0,1,0],dtype=torch.int8)
-print(torch.logical_or(a,b))
-# tensor([ True, True, True, False])
-```
-
-```python
-r = torch.tensor([[0,0,0,0],[0,0,0,0]])
-mask = torch.tensor([[1,1,1,1],[0,0,0,0]])
-print(r.masked_fill(mask,1))
-# tensor([[1, 1, 1, 1],
-# [0, 0, 0, 0]])
-```
-其实attn_mask和key_padding_mask有些时候对象是一致的,所以有时候可以合起来看。`-inf`做softmax之后值为0,即被忽略。
-```python
-if key_padding_mask is not None:
- assert key_padding_mask.shape == (bsz, src_len), \
- f"expecting key_padding_mask shape of {(bsz, src_len)}, but got {key_padding_mask.shape}"
- key_padding_mask = key_padding_mask.view(bsz, 1, 1, src_len). \
- expand(-1, num_heads, -1, -1).reshape(bsz * num_heads, 1, src_len)
- # 若attn_mask为空,直接用key_padding_mask
- if attn_mask is None:
- attn_mask = key_padding_mask
- elif attn_mask.dtype == torch.bool:
- attn_mask = attn_mask.logical_or(key_padding_mask)
- else:
- attn_mask = attn_mask.masked_fill(key_padding_mask, float("-inf"))
-
-# 若attn_mask值是布尔值,则将mask转换为float
-if attn_mask is not None and attn_mask.dtype == torch.bool:
- new_attn_mask = torch.zeros_like(attn_mask, dtype=torch.float)
- new_attn_mask.masked_fill_(attn_mask, float("-inf"))
- attn_mask = new_attn_mask
-
-```
-
-***
-##### 点积注意力
-
-
-```python
-from typing import Optional, Tuple, Any
-def _scaled_dot_product_attention(
- q: Tensor,
- k: Tensor,
- v: Tensor,
- attn_mask: Optional[Tensor] = None,
- dropout_p: float = 0.0,
-) -> Tuple[Tensor, Tensor]:
- r'''
- 在query, key, value上计算点积注意力,若有注意力遮盖则使用,并且应用一个概率为dropout_p的dropout
-
- 参数:
- - q: shape:`(B, Nt, E)` B代表batch size, Nt是目标语言序列长度,E是嵌入后的特征维度
- - key: shape:`(B, Ns, E)` Ns是源语言序列长度
- - value: shape:`(B, Ns, E)`与key形状一样
- - attn_mask: 要么是3D的tensor,形状为:`(B, Nt, Ns)`或者2D的tensor,形状如:`(Nt, Ns)`
-
- - Output: attention values: shape:`(B, Nt, E)`,与q的形状一致;attention weights: shape:`(B, Nt, Ns)`
-
- 例子:
- >>> q = torch.randn((2,3,6))
- >>> k = torch.randn((2,4,6))
- >>> v = torch.randn((2,4,6))
- >>> out = scaled_dot_product_attention(q, k, v)
- >>> out[0].shape, out[1].shape
- >>> torch.Size([2, 3, 6]) torch.Size([2, 3, 4])
- '''
- B, Nt, E = q.shape
- q = q / math.sqrt(E)
- # (B, Nt, E) x (B, E, Ns) -> (B, Nt, Ns)
- attn = torch.bmm(q, k.transpose(-2,-1))
- if attn_mask is not None:
- attn += attn_mask
- # attn意味着目标序列的每个词对源语言序列做注意力
- attn = F.softmax(attn, dim=-1)
- if dropout_p:
- attn = F.dropout(attn, p=dropout_p)
- # (B, Nt, Ns) x (B, Ns, E) -> (B, Nt, E)
- output = torch.bmm(attn, v)
- return output, attn
-
-```
-### **完整的多头注意力机制-MultiheadAttention
**
-[点击快速回到:拆开看多头注意力机制](#拆开看多头注意力机制)
-
-```python
-class MultiheadAttention(nn.Module):
- r'''
- 参数:
- embed_dim: 词嵌入的维度
- num_heads: 平行头的数量
- batch_first: 若`True`,则为(batch, seq, feture),若为`False`,则为(seq, batch, feature)
-
- 例子:
- >>> multihead_attn = MultiheadAttention(embed_dim, num_heads)
- >>> attn_output, attn_output_weights = multihead_attn(query, key, value)
- '''
- def __init__(self, embed_dim, num_heads, dropout=0., bias=True,
- kdim=None, vdim=None, batch_first=False) -> None:
- # factory_kwargs = {'device': device, 'dtype': dtype}
- super(MultiheadAttention, self).__init__()
- self.embed_dim = embed_dim
- self.kdim = kdim if kdim is not None else embed_dim
- self.vdim = vdim if vdim is not None else embed_dim
- self._qkv_same_embed_dim = self.kdim == embed_dim and self.vdim == embed_dim
-
- self.num_heads = num_heads
- self.dropout = dropout
- self.batch_first = batch_first
- self.head_dim = embed_dim // num_heads
- assert self.head_dim * num_heads == self.embed_dim, "embed_dim must be divisible by num_heads"
-
- if self._qkv_same_embed_dim is False:
- self.q_proj_weight = Parameter(torch.empty((embed_dim, embed_dim)))
- self.k_proj_weight = Parameter(torch.empty((embed_dim, self.kdim)))
- self.v_proj_weight = Parameter(torch.empty((embed_dim, self.vdim)))
- self.register_parameter('in_proj_weight', None)
- else:
- self.in_proj_weight = Parameter(torch.empty((3 * embed_dim, embed_dim)))
- self.register_parameter('q_proj_weight', None)
- self.register_parameter('k_proj_weight', None)
- self.register_parameter('v_proj_weight', None)
-
- if bias:
- self.in_proj_bias = Parameter(torch.empty(3 * embed_dim))
- else:
- self.register_parameter('in_proj_bias', None)
- self.out_proj = nn.Linear(embed_dim, embed_dim, bias=bias)
-
- self._reset_parameters()
-
- def _reset_parameters(self):
- if self._qkv_same_embed_dim:
- xavier_uniform_(self.in_proj_weight)
- else:
- xavier_uniform_(self.q_proj_weight)
- xavier_uniform_(self.k_proj_weight)
- xavier_uniform_(self.v_proj_weight)
-
- if self.in_proj_bias is not None:
- constant_(self.in_proj_bias, 0.)
- constant_(self.out_proj.bias, 0.)
-
-
-
- def forward(self, query: Tensor, key: Tensor, value: Tensor, key_padding_mask: Optional[Tensor] = None,
- need_weights: bool = True, attn_mask: Optional[Tensor] = None) -> Tuple[Tensor, Optional[Tensor]]:
- if self.batch_first:
- query, key, value = [x.transpose(1, 0) for x in (query, key, value)]
-
- if not self._qkv_same_embed_dim:
- attn_output, attn_output_weights = multi_head_attention_forward(
- query, key, value, self.num_heads,
- self.in_proj_weight, self.in_proj_bias,
- self.dropout, self.out_proj.weight, self.out_proj.bias,
- training=self.training,
- key_padding_mask=key_padding_mask, need_weights=need_weights,
- attn_mask=attn_mask, use_separate_proj_weight=True,
- q_proj_weight=self.q_proj_weight, k_proj_weight=self.k_proj_weight,
- v_proj_weight=self.v_proj_weight)
- else:
- attn_output, attn_output_weights = multi_head_attention_forward(
- query, key, value, self.num_heads,
- self.in_proj_weight, self.in_proj_bias,
- self.dropout, self.out_proj.weight, self.out_proj.bias,
- training=self.training,
- key_padding_mask=key_padding_mask, need_weights=need_weights,
- attn_mask=attn_mask)
- if self.batch_first:
- return attn_output.transpose(1, 0), attn_output_weights
- else:
- return attn_output, attn_output_weights
-```
-
-
-接下来可以实践一下,并且把位置编码加起来,可以发现加入位置编码和进行多头注意力的前后形状都是不会变的
-
-
-```python
-# 因为batch_first为False,所以src的shape:`(seq, batch, embed_dim)`
-src = torch.randn((2,4,100))
-src = positional_encoding(src,100,0.1)
-print(src.shape)
-multihead_attn = MultiheadAttention(100, 4, 0.1)
-attn_output, attn_output_weights = multihead_attn(src,src,src)
-print(attn_output.shape, attn_output_weights.shape)
-
-# torch.Size([2, 4, 100])
-# torch.Size([2, 4, 100]) torch.Size([4, 2, 2])
-```
-
- torch.Size([2, 4, 100])
- torch.Size([2, 4, 100]) torch.Size([4, 2, 2])
-
-
-***
-## **TransformerEncoderLayer
**
-- Encoder Layer
-
-
-
-
-```python
-class TransformerEncoderLayer(nn.Module):
- r'''
- 参数:
- d_model: 词嵌入的维度(必备)
- nhead: 多头注意力中平行头的数目(必备)
- dim_feedforward: 全连接层的神经元的数目,又称经过此层输入的维度(Default = 2048)
- dropout: dropout的概率(Default = 0.1)
- activation: 两个线性层中间的激活函数,默认relu或gelu
- lay_norm_eps: layer normalization中的微小量,防止分母为0(Default = 1e-5)
- batch_first: 若`True`,则为(batch, seq, feture),若为`False`,则为(seq, batch, feature)(Default:False)
-
- 例子:
- >>> encoder_layer = TransformerEncoderLayer(d_model=512, nhead=8)
- >>> src = torch.randn((32, 10, 512))
- >>> out = encoder_layer(src)
- '''
-
- def __init__(self, d_model, nhead, dim_feedforward=2048, dropout=0.1, activation=F.relu,
- layer_norm_eps=1e-5, batch_first=False) -> None:
- super(TransformerEncoderLayer, self).__init__()
- self.self_attn = MultiheadAttention(d_model, nhead, dropout=dropout, batch_first=batch_first)
- self.linear1 = nn.Linear(d_model, dim_feedforward)
- self.dropout = nn.Dropout(dropout)
- self.linear2 = nn.Linear(dim_feedforward, d_model)
-
- self.norm1 = nn.LayerNorm(d_model, eps=layer_norm_eps)
- self.norm2 = nn.LayerNorm(d_model, eps=layer_norm_eps)
- self.dropout1 = nn.Dropout(dropout)
- self.dropout2 = nn.Dropout(dropout)
- self.activation = activation
-
-
- def forward(self, src: Tensor, src_mask: Optional[Tensor] = None, src_key_padding_mask: Optional[Tensor] = None) -> Tensor:
- src = positional_encoding(src, src.shape[-1])
- src2 = self.self_attn(src, src, src, attn_mask=src_mask,
- key_padding_mask=src_key_padding_mask)[0]
- src = src + self.dropout1(src2)
- src = self.norm1(src)
- src2 = self.linear2(self.dropout(self.activation(self.linear1(src))))
- src = src + self.dropout(src2)
- src = self.norm2(src)
- return src
-
-```
-
-
-```python
-# 用小例子看一下
-encoder_layer = TransformerEncoderLayer(d_model=512, nhead=8)
-src = torch.randn((32, 10, 512))
-out = encoder_layer(src)
-print(out.shape)
-# torch.Size([32, 10, 512])
-```
-
-
-## Transformer layer组成Encoder
-
-```python
-class TransformerEncoder(nn.Module):
- r'''
- 参数:
- encoder_layer(必备)
- num_layers: encoder_layer的层数(必备)
- norm: 归一化的选择(可选)
-
- 例子:
- >>> encoder_layer = TransformerEncoderLayer(d_model=512, nhead=8)
- >>> transformer_encoder = TransformerEncoder(encoder_layer, num_layers=6)
- >>> src = torch.randn((10, 32, 512))
- >>> out = transformer_encoder(src)
- '''
-
- def __init__(self, encoder_layer, num_layers, norm=None):
- super(TransformerEncoder, self).__init__()
- self.layer = encoder_layer
- self.num_layers = num_layers
- self.norm = norm
-
- def forward(self, src: Tensor, mask: Optional[Tensor] = None, src_key_padding_mask: Optional[Tensor] = None) -> Tensor:
- output = positional_encoding(src, src.shape[-1])
- for _ in range(self.num_layers):
- output = self.layer(output, src_mask=mask, src_key_padding_mask=src_key_padding_mask)
-
- if self.norm is not None:
- output = self.norm(output)
-
- return output
-```
-
-```python
-# 例子
-encoder_layer = TransformerEncoderLayer(d_model=512, nhead=8)
-transformer_encoder = TransformerEncoder(encoder_layer, num_layers=6)
-src = torch.randn((10, 32, 512))
-out = transformer_encoder(src)
-print(out.shape)
-# torch.Size([10, 32, 512])
-```
-
-***
-## Decoder Layer:
-
-
-```python
-class TransformerDecoderLayer(nn.Module):
- r'''
- 参数:
- d_model: 词嵌入的维度(必备)
- nhead: 多头注意力中平行头的数目(必备)
- dim_feedforward: 全连接层的神经元的数目,又称经过此层输入的维度(Default = 2048)
- dropout: dropout的概率(Default = 0.1)
- activation: 两个线性层中间的激活函数,默认relu或gelu
- lay_norm_eps: layer normalization中的微小量,防止分母为0(Default = 1e-5)
- batch_first: 若`True`,则为(batch, seq, feture),若为`False`,则为(seq, batch, feature)(Default:False)
-
- 例子:
- >>> decoder_layer = TransformerDecoderLayer(d_model=512, nhead=8)
- >>> memory = torch.randn((10, 32, 512))
- >>> tgt = torch.randn((20, 32, 512))
- >>> out = decoder_layer(tgt, memory)
- '''
- def __init__(self, d_model, nhead, dim_feedforward=2048, dropout=0.1, activation=F.relu,
- layer_norm_eps=1e-5, batch_first=False) -> None:
- super(TransformerDecoderLayer, self).__init__()
- self.self_attn = MultiheadAttention(d_model, nhead, dropout=dropout, batch_first=batch_first)
- self.multihead_attn = MultiheadAttention(d_model, nhead, dropout=dropout, batch_first=batch_first)
-
- self.linear1 = nn.Linear(d_model, dim_feedforward)
- self.dropout = nn.Dropout(dropout)
- self.linear2 = nn.Linear(dim_feedforward, d_model)
-
- self.norm1 = nn.LayerNorm(d_model, eps=layer_norm_eps)
- self.norm2 = nn.LayerNorm(d_model, eps=layer_norm_eps)
- self.norm3 = nn.LayerNorm(d_model, eps=layer_norm_eps)
- self.dropout1 = nn.Dropout(dropout)
- self.dropout2 = nn.Dropout(dropout)
- self.dropout3 = nn.Dropout(dropout)
-
- self.activation = activation
-
- def forward(self, tgt: Tensor, memory: Tensor, tgt_mask: Optional[Tensor] = None,
- memory_mask: Optional[Tensor] = None,tgt_key_padding_mask: Optional[Tensor] = None, memory_key_padding_mask: Optional[Tensor] = None) -> Tensor:
- r'''
- 参数:
- tgt: 目标语言序列(必备)
- memory: 从最后一个encoder_layer跑出的句子(必备)
- tgt_mask: 目标语言序列的mask(可选)
- memory_mask(可选)
- tgt_key_padding_mask(可选)
- memory_key_padding_mask(可选)
- '''
- tgt2 = self.self_attn(tgt, tgt, tgt, attn_mask=tgt_mask,
- key_padding_mask=tgt_key_padding_mask)[0]
- tgt = tgt + self.dropout1(tgt2)
- tgt = self.norm1(tgt)
- tgt2 = self.multihead_attn(tgt, memory, memory, attn_mask=memory_mask,
- key_padding_mask=memory_key_padding_mask)[0]
- tgt = tgt + self.dropout2(tgt2)
- tgt = self.norm2(tgt)
- tgt2 = self.linear2(self.dropout(self.activation(self.linear1(tgt))))
- tgt = tgt + self.dropout3(tgt2)
- tgt = self.norm3(tgt)
- return tgt
-```
-
-
-```python
-# 可爱的小例子
-decoder_layer = nn.TransformerDecoderLayer(d_model=512, nhead=8)
-memory = torch.randn((10, 32, 512))
-tgt = torch.randn((20, 32, 512))
-out = decoder_layer(tgt, memory)
-print(out.shape)
-# torch.Size([20, 32, 512])
-```
-
-```python
-## Decoder
-```
-
-
-```python
-class TransformerDecoder(nn.Module):
- r'''
- 参数:
- decoder_layer(必备)
- num_layers: decoder_layer的层数(必备)
- norm: 归一化选择
-
- 例子:
- >>> decoder_layer =TransformerDecoderLayer(d_model=512, nhead=8)
- >>> transformer_decoder = TransformerDecoder(decoder_layer, num_layers=6)
- >>> memory = torch.rand(10, 32, 512)
- >>> tgt = torch.rand(20, 32, 512)
- >>> out = transformer_decoder(tgt, memory)
- '''
- def __init__(self, decoder_layer, num_layers, norm=None):
- super(TransformerDecoder, self).__init__()
- self.layer = decoder_layer
- self.num_layers = num_layers
- self.norm = norm
-
- def forward(self, tgt: Tensor, memory: Tensor, tgt_mask: Optional[Tensor] = None,
- memory_mask: Optional[Tensor] = None, tgt_key_padding_mask: Optional[Tensor] = None,
- memory_key_padding_mask: Optional[Tensor] = None) -> Tensor:
- output = tgt
- for _ in range(self.num_layers):
- output = self.layer(output, memory, tgt_mask=tgt_mask,
- memory_mask=memory_mask,
- tgt_key_padding_mask=tgt_key_padding_mask,
- memory_key_padding_mask=memory_key_padding_mask)
- if self.norm is not None:
- output = self.norm(output)
-
- return output
-```
-
-```python
-# 可爱的小例子
-decoder_layer =TransformerDecoderLayer(d_model=512, nhead=8)
-transformer_decoder = TransformerDecoder(decoder_layer, num_layers=6)
-memory = torch.rand(10, 32, 512)
-tgt = torch.rand(20, 32, 512)
-out = transformer_decoder(tgt, memory)
-print(out.shape)
-# torch.Size([20, 32, 512])
-```
-
-
-总结一下,其实经过位置编码,多头注意力,Encoder Layer和Decoder Layer形状不会变的,而Encoder和Decoder分别与src和tgt形状一致
-
-## Transformer
-
-
-```python
-class Transformer(nn.Module):
- r'''
- 参数:
- d_model: 词嵌入的维度(必备)(Default=512)
- nhead: 多头注意力中平行头的数目(必备)(Default=8)
- num_encoder_layers:编码层层数(Default=8)
- num_decoder_layers:解码层层数(Default=8)
- dim_feedforward: 全连接层的神经元的数目,又称经过此层输入的维度(Default = 2048)
- dropout: dropout的概率(Default = 0.1)
- activation: 两个线性层中间的激活函数,默认relu或gelu
- custom_encoder: 自定义encoder(Default=None)
- custom_decoder: 自定义decoder(Default=None)
- lay_norm_eps: layer normalization中的微小量,防止分母为0(Default = 1e-5)
- batch_first: 若`True`,则为(batch, seq, feture),若为`False`,则为(seq, batch, feature)(Default:False)
-
- 例子:
- >>> transformer_model = Transformer(nhead=16, num_encoder_layers=12)
- >>> src = torch.rand((10, 32, 512))
- >>> tgt = torch.rand((20, 32, 512))
- >>> out = transformer_model(src, tgt)
- '''
- def __init__(self, d_model: int = 512, nhead: int = 8, num_encoder_layers: int = 6,
- num_decoder_layers: int = 6, dim_feedforward: int = 2048, dropout: float = 0.1,
- activation = F.relu, custom_encoder: Optional[Any] = None, custom_decoder: Optional[Any] = None,
- layer_norm_eps: float = 1e-5, batch_first: bool = False) -> None:
- super(Transformer, self).__init__()
- if custom_encoder is not None:
- self.encoder = custom_encoder
- else:
- encoder_layer = TransformerEncoderLayer(d_model, nhead, dim_feedforward, dropout,
- activation, layer_norm_eps, batch_first)
- encoder_norm = nn.LayerNorm(d_model, eps=layer_norm_eps)
- self.encoder = TransformerEncoder(encoder_layer, num_encoder_layers)
-
- if custom_decoder is not None:
- self.decoder = custom_decoder
- else:
- decoder_layer = TransformerDecoderLayer(d_model, nhead, dim_feedforward, dropout,
- activation, layer_norm_eps, batch_first)
- decoder_norm = nn.LayerNorm(d_model, eps=layer_norm_eps)
- self.decoder = TransformerDecoder(decoder_layer, num_decoder_layers, decoder_norm)
-
- self._reset_parameters()
-
- self.d_model = d_model
- self.nhead = nhead
-
- self.batch_first = batch_first
-
- def forward(self, src: Tensor, tgt: Tensor, src_mask: Optional[Tensor] = None, tgt_mask: Optional[Tensor] = None,
- memory_mask: Optional[Tensor] = None, src_key_padding_mask: Optional[Tensor] = None,
- tgt_key_padding_mask: Optional[Tensor] = None, memory_key_padding_mask: Optional[Tensor] = None) -> Tensor:
- r'''
- 参数:
- src: 源语言序列(送入Encoder)(必备)
- tgt: 目标语言序列(送入Decoder)(必备)
- src_mask: (可选)
- tgt_mask: (可选)
- memory_mask: (可选)
- src_key_padding_mask: (可选)
- tgt_key_padding_mask: (可选)
- memory_key_padding_mask: (可选)
-
- 形状:
- - src: shape:`(S, N, E)`, `(N, S, E)` if batch_first.
- - tgt: shape:`(T, N, E)`, `(N, T, E)` if batch_first.
- - src_mask: shape:`(S, S)`.
- - tgt_mask: shape:`(T, T)`.
- - memory_mask: shape:`(T, S)`.
- - src_key_padding_mask: shape:`(N, S)`.
- - tgt_key_padding_mask: shape:`(N, T)`.
- - memory_key_padding_mask: shape:`(N, S)`.
-
- [src/tgt/memory]_mask确保有些位置不被看到,如做decode的时候,只能看该位置及其以前的,而不能看后面的。
- 若为ByteTensor,非0的位置会被忽略不做注意力;若为BoolTensor,True对应的位置会被忽略;
- 若为数值,则会直接加到attn_weights
-
- [src/tgt/memory]_key_padding_mask 使得key里面的某些元素不参与attention计算,三种情况同上
-
- - output: shape:`(T, N, E)`, `(N, T, E)` if batch_first.
-
- 注意:
- src和tgt的最后一维需要等于d_model,batch的那一维需要相等
-
- 例子:
- >>> output = transformer_model(src, tgt, src_mask=src_mask, tgt_mask=tgt_mask)
- '''
- memory = self.encoder(src, mask=src_mask, src_key_padding_mask=src_key_padding_mask)
- output = self.decoder(tgt, memory, tgt_mask=tgt_mask, memory_mask=memory_mask,
- tgt_key_padding_mask=tgt_key_padding_mask,
- memory_key_padding_mask=memory_key_padding_mask)
- return output
-
- def generate_square_subsequent_mask(self, sz: int) -> Tensor:
- r'''产生关于序列的mask,被遮住的区域赋值`-inf`,未被遮住的区域赋值为`0`'''
- mask = (torch.triu(torch.ones(sz, sz)) == 1).transpose(0, 1)
- mask = mask.float().masked_fill(mask == 0, float('-inf')).masked_fill(mask == 1, float(0.0))
- return mask
-
- def _reset_parameters(self):
- r'''用正态分布初始化参数'''
- for p in self.parameters():
- if p.dim() > 1:
- xavier_uniform_(p)
-```
-
-```python
-# 小例子
-transformer_model = Transformer(nhead=16, num_encoder_layers=12)
-src = torch.rand((10, 32, 512))
-tgt = torch.rand((20, 32, 512))
-out = transformer_model(src, tgt)
-print(out.shape)
-# torch.Size([20, 32, 512])
-```
-
-到此为止,PyTorch的Transformer库我们已经全部实现,相比于官方的版本,手写的这个少了较多的判定语句。
-## 致谢
-本文由台运鹏撰写,本项目成员重新组织和整理。最后,期待您的阅读反馈和star,谢谢。
diff --git a/requirements.txt b/requirements.txt
index 00806ef..21f349f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,3 +4,7 @@ notebook
torch==1.9.0
sklearn
scipy
+matplotlib
+torchtext
+seaborn
+spacy