{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 使用Modules和Models快速搭建自定义模型\n",
    "\n",
    "modules 和 models 用于构建 fastNLP 所需的神经网络模型，它可以和 torch.nn 中的模型一起使用。 下面我们会分三节介绍编写构建模型的具体方法。\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "我们首先准备好和上篇教程一样的基础实验代码"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "from fastNLP.io import SST2Pipe\n",
    "from fastNLP import Trainer, CrossEntropyLoss, AccuracyMetric\n",
    "import torch\n",
    "\n",
    "databundle = SST2Pipe().process_from_file()\n",
    "vocab = databundle.get_vocab('words')\n",
    "train_data = databundle.get_dataset('train')[:5000]\n",
    "train_data, test_data = train_data.split(0.015)\n",
    "dev_data = databundle.get_dataset('dev')\n",
    "\n",
    "loss = CrossEntropyLoss()\n",
    "metric = AccuracyMetric()\n",
    "device = 0 if torch.cuda.is_available() else 'cpu'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 使用 models 中的模型\n",
    "\n",
    "fastNLP 在 models 模块中内置了如 CNNText 、 SeqLabeling 等完整的模型，以供用户直接使用。 以文本分类的任务为例，我们从 models 中导入 CNNText 模型，用它进行训练。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "input fields after batch(if batch size is 2):\n",
      "\twords: (1)type:torch.Tensor (2)dtype:torch.int64, (3)shape:torch.Size([2, 41]) \n",
      "\tseq_len: (1)type:torch.Tensor (2)dtype:torch.int64, (3)shape:torch.Size([2]) \n",
      "target fields after batch(if batch size is 2):\n",
      "\ttarget: (1)type:torch.Tensor (2)dtype:torch.int64, (3)shape:torch.Size([2]) \n",
      "\n",
      "training epochs started 2020-02-28-00-56-04\n"
     ]
    },
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      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.22 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 1/10. Step:154/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.760321\n",
      "\n"
     ]
    },
    {
     "data": {
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       "model_id": "",
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       "version_minor": 0
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      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.29 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 2/10. Step:308/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.727064\n",
      "\n"
     ]
    },
    {
     "data": {
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     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.48 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 3/10. Step:462/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.758028\n",
      "\n"
     ]
    },
    {
     "data": {
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     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.24 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 4/10. Step:616/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.759174\n",
      "\n"
     ]
    },
    {
     "data": {
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     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.47 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 5/10. Step:770/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.743119\n",
      "\n"
     ]
    },
    {
     "data": {
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     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.22 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 6/10. Step:924/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.756881\n",
      "\n"
     ]
    },
    {
     "data": {
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       "model_id": "",
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       "version_minor": 0
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     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.21 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 7/10. Step:1078/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.752294\n",
      "\n"
     ]
    },
    {
     "data": {
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       "model_id": "",
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       "version_minor": 0
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     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.21 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 8/10. Step:1232/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.756881\n",
      "\n"
     ]
    },
    {
     "data": {
      "application/vnd.jupyter.widget-view+json": {
       "model_id": "",
       "version_major": 2,
       "version_minor": 0
      },
      "text/plain": [
       "HBox(children=(FloatProgress(value=0.0, layout=Layout(flex='2'), max=28.0), HTML(value='')), layout=Layout(dis…"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.15 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 9/10. Step:1386/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.75344\n",
      "\n"
     ]
    },
    {
     "data": {
      "application/vnd.jupyter.widget-view+json": {
       "model_id": "",
       "version_major": 2,
       "version_minor": 0
      },
      "text/plain": [
       "HBox(children=(FloatProgress(value=0.0, layout=Layout(flex='2'), max=28.0), HTML(value='')), layout=Layout(dis…"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.12 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 10/10. Step:1540/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.752294\n",
      "\n",
      "\r\n",
      "In Epoch:1/Step:154, got best dev performance:\n",
      "AccuracyMetric: acc=0.760321\n",
      "Reloaded the best model.\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "{'best_eval': {'AccuracyMetric': {'acc': 0.760321}},\n",
       " 'best_epoch': 1,\n",
       " 'best_step': 154,\n",
       " 'seconds': 29.3}"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "from fastNLP.models import CNNText\n",
    "\n",
    "model_cnn = CNNText((len(vocab),100), num_classes=2, dropout=0.1)\n",
    "\n",
    "trainer = Trainer(train_data=train_data, dev_data=dev_data, metrics=metric,\n",
    "                  loss=loss, device=device, model=model_cnn)\n",
    "trainer.train()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "在 iPython 环境输入 model_cnn ，我们可以看到 model_cnn 的网络结构"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "CNNText(\n",
       "  (embed): Embedding(\n",
       "    (embed): Embedding(16292, 100)\n",
       "    (dropout): Dropout(p=0.0, inplace=False)\n",
       "  )\n",
       "  (conv_pool): ConvMaxpool(\n",
       "    (convs): ModuleList(\n",
       "      (0): Conv1d(100, 30, kernel_size=(1,), stride=(1,), bias=False)\n",
       "      (1): Conv1d(100, 40, kernel_size=(3,), stride=(1,), padding=(1,), bias=False)\n",
       "      (2): Conv1d(100, 50, kernel_size=(5,), stride=(1,), padding=(2,), bias=False)\n",
       "    )\n",
       "  )\n",
       "  (dropout): Dropout(p=0.1, inplace=False)\n",
       "  (fc): Linear(in_features=120, out_features=2, bias=True)\n",
       ")"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "model_cnn"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 使用 nn.torch 编写模型\n",
    "\n",
    "FastNLP 完全支持使用 pyTorch 编写的模型，但与 pyTorch 中编写模型的常见方法不同， 用于 fastNLP 的模型中 forward 函数需要返回一个字典，字典中至少需要包含 pred 这个字段。\n",
    "\n",
    "下面是使用 pyTorch 中的 torch.nn 模块编写的文本分类，注意观察代码中标注的向量维度。 由于 pyTorch 使用了约定俗成的维度设置，使得 forward 中需要多次处理维度顺序"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "import torch\n",
    "import torch.nn as nn\n",
    "\n",
    "class LSTMText(nn.Module):\n",
    "    def __init__(self, vocab_size, embedding_dim, output_dim, hidden_dim=64, num_layers=2, dropout=0.5):\n",
    "        super().__init__()\n",
    "\n",
    "        self.embedding = nn.Embedding(vocab_size, embedding_dim)\n",
    "        self.lstm = nn.LSTM(embedding_dim, hidden_dim, num_layers=num_layers, bidirectional=True, dropout=dropout)\n",
    "        self.fc = nn.Linear(hidden_dim * 2, output_dim)\n",
    "        self.dropout = nn.Dropout(dropout)\n",
    "\n",
    "    def forward(self, words):\n",
    "        # (input) words : (batch_size, seq_len)\n",
    "        words = words.permute(1,0)\n",
    "        # words : (seq_len, batch_size)\n",
    "\n",
    "        embedded = self.dropout(self.embedding(words))\n",
    "        # embedded : (seq_len, batch_size, embedding_dim)\n",
    "        output, (hidden, cell) = self.lstm(embedded)\n",
    "        # output: (seq_len, batch_size, hidden_dim * 2)\n",
    "        # hidden: (num_layers * 2, batch_size, hidden_dim)\n",
    "        # cell: (num_layers * 2, batch_size, hidden_dim)\n",
    "\n",
    "        hidden = torch.cat((hidden[-2, :, :], hidden[-1, :, :]), dim=1)\n",
    "        hidden = self.dropout(hidden)\n",
    "        # hidden: (batch_size, hidden_dim * 2)\n",
    "\n",
    "        pred = self.fc(hidden.squeeze(0))\n",
    "        # result: (batch_size, output_dim)\n",
    "        return {\"pred\":pred}"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "我们同样可以在 iPython 环境中查看这个模型的网络结构"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "LSTMText(\n",
       "  (embedding): Embedding(16292, 100)\n",
       "  (lstm): LSTM(100, 64, num_layers=2, dropout=0.5, bidirectional=True)\n",
       "  (fc): Linear(in_features=128, out_features=2, bias=True)\n",
       "  (dropout): Dropout(p=0.5, inplace=False)\n",
       ")"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "model_lstm = LSTMText(len(vocab), 100, 2)\n",
    "model_lstm                      "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "input fields after batch(if batch size is 2):\n",
      "\twords: (1)type:torch.Tensor (2)dtype:torch.int64, (3)shape:torch.Size([2, 41]) \n",
      "\tseq_len: (1)type:torch.Tensor (2)dtype:torch.int64, (3)shape:torch.Size([2]) \n",
      "target fields after batch(if batch size is 2):\n",
      "\ttarget: (1)type:torch.Tensor (2)dtype:torch.int64, (3)shape:torch.Size([2]) \n",
      "\n",
      "training epochs started 2020-02-28-00-56-34\n"
     ]
    },
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    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.36 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 1/10. Step:154/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.59289\n",
      "\n"
     ]
    },
    {
     "data": {
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       "version_minor": 0
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     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.35 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 2/10. Step:308/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.674312\n",
      "\n"
     ]
    },
    {
     "data": {
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     "metadata": {},
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    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.21 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 3/10. Step:462/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.724771\n",
      "\n"
     ]
    },
    {
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    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.4 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 4/10. Step:616/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.748853\n",
      "\n"
     ]
    },
    {
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     "metadata": {},
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    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.24 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 5/10. Step:770/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.756881\n",
      "\n"
     ]
    },
    {
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     },
     "metadata": {},
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    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.29 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 6/10. Step:924/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.741972\n",
      "\n"
     ]
    },
    {
     "data": {
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       "version_minor": 0
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     },
     "metadata": {},
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    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.32 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 7/10. Step:1078/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.754587\n",
      "\n"
     ]
    },
    {
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      "text/plain": [
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    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.24 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 8/10. Step:1232/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.756881\n",
      "\n"
     ]
    },
    {
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     "metadata": {},
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    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.28 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 9/10. Step:1386/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.740826\n",
      "\n"
     ]
    },
    {
     "data": {
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       "version_minor": 0
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     },
     "metadata": {},
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    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.23 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 10/10. Step:1540/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.751147\n",
      "\n",
      "\r\n",
      "In Epoch:5/Step:770, got best dev performance:\n",
      "AccuracyMetric: acc=0.756881\n",
      "Reloaded the best model.\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "{'best_eval': {'AccuracyMetric': {'acc': 0.756881}},\n",
       " 'best_epoch': 5,\n",
       " 'best_step': 770,\n",
       " 'seconds': 45.69}"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "trainer = Trainer(train_data=train_data, dev_data=dev_data, metrics=metric,\n",
    "                  loss=loss, device=device, model=model_lstm)\n",
    "trainer.train()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 使用 modules 编写模型\n",
    "\n",
    "下面我们使用 fastNLP.modules 中的组件来构建同样的网络。由于 fastNLP 统一把 batch_size 放在第一维， 在编写代码的过程中会有一定的便利。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "MyText(\n",
       "  (embedding): Embedding(\n",
       "    (embed): Embedding(16292, 100)\n",
       "    (dropout): Dropout(p=0.0, inplace=False)\n",
       "  )\n",
       "  (lstm): LSTM(\n",
       "    (lstm): LSTM(100, 64, num_layers=2, batch_first=True, bidirectional=True)\n",
       "  )\n",
       "  (mlp): MLP(\n",
       "    (hiddens): ModuleList()\n",
       "    (output): Linear(in_features=128, out_features=2, bias=True)\n",
       "    (dropout): Dropout(p=0.5, inplace=False)\n",
       "  )\n",
       ")"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "from fastNLP.modules import LSTM, MLP\n",
    "from fastNLP.embeddings import Embedding\n",
    "\n",
    "\n",
    "class MyText(nn.Module):\n",
    "    def __init__(self, vocab_size, embedding_dim, output_dim, hidden_dim=64, num_layers=2, dropout=0.5):\n",
    "        super().__init__()\n",
    "\n",
    "        self.embedding = Embedding((vocab_size, embedding_dim))\n",
    "        self.lstm = LSTM(embedding_dim, hidden_dim, num_layers=num_layers, bidirectional=True)\n",
    "        self.mlp = MLP([hidden_dim*2,output_dim], dropout=dropout)\n",
    "\n",
    "    def forward(self, words):\n",
    "        embedded = self.embedding(words)\n",
    "        _,(hidden,_) = self.lstm(embedded)\n",
    "        pred = self.mlp(torch.cat((hidden[-1],hidden[-2]),dim=1))\n",
    "        return {\"pred\":pred}\n",
    "    \n",
    "model_text = MyText(len(vocab), 100, 2)\n",
    "model_text"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "input fields after batch(if batch size is 2):\n",
      "\twords: (1)type:torch.Tensor (2)dtype:torch.int64, (3)shape:torch.Size([2, 41]) \n",
      "\tseq_len: (1)type:torch.Tensor (2)dtype:torch.int64, (3)shape:torch.Size([2]) \n",
      "target fields after batch(if batch size is 2):\n",
      "\ttarget: (1)type:torch.Tensor (2)dtype:torch.int64, (3)shape:torch.Size([2]) \n",
      "\n",
      "training epochs started 2020-02-28-00-57-19\n"
     ]
    },
    {
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       "version_minor": 0
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       "HBox(children=(FloatProgress(value=0.0, layout=Layout(flex='2'), max=1540.0), HTML(value='')), layout=Layout(d…"
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    {
     "data": {
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       "version_minor": 0
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     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.38 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 1/10. Step:154/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.767202\n",
      "\n"
     ]
    },
    {
     "data": {
      "application/vnd.jupyter.widget-view+json": {
       "model_id": "",
       "version_major": 2,
       "version_minor": 0
      },
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       "HBox(children=(FloatProgress(value=0.0, layout=Layout(flex='2'), max=28.0), HTML(value='')), layout=Layout(dis…"
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     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\r",
      "Evaluate data in 0.22 seconds!\n",
      "\r",
      "Evaluation on dev at Epoch 2/10. Step:308/1540: \n",
      "\r",
      "AccuracyMetric: acc=0.743119\n",
      "\n"
     ]
    }
   ],
   "source": [
    "trainer = Trainer(train_data=train_data, dev_data=dev_data, metrics=metric,\n",
    "                  loss=loss, device=device, model=model_lstm)\n",
    "trainer.train()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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