Pytorch-使用Bert预训练模型微调中文文本分类

笔记摘抄

语料链接:https://pan.baidu.com/s/1YxGGYmeByuAlRdAVov_ZLg
提取码:tzao

neg.txt和pos.txt各5000条酒店评论,每条评论一行。

1. 导包和设定超参数

import numpy as np
import random
import torch
import matplotlib.pylab as plt 
from torch.nn.utils import clip_grad_norm_
from torch.utils.data import TensorDataset, DataLoader, RandomSampler, SequentialSampler
from transformers import BertTokenizer, BertForSequenceClassification, AdamW
from transformers import get_linear_schedule_with_warmup

SEED = 123
BATCH_SIZE = 16
learning_rate = 2e-5
weight_decay = 1e-2
epsilon = 1e-8

random.seed(SEED)
np.random.seed(SEED)
torch.manual_seed(SEED)

2. 数据预处理

2.1 读取文件

def readFile(filename):
    with open(filename, encoding='utf-8') as f:
        content = f.readlines()
        return content

pos_text, neg_text = readFile('./hotel/pos.txt'), readFile('./hotel/neg.txt')
sentences = pos_text + neg_text

# 设定标签
pos_targets = np.ones([len(pos_text)])  # (5000, )
neg_targets = np.zeros([len(neg_text)]) # (5000, )
targets = np.concatenate((pos_targets, neg_targets), axis=0).reshape(-1, 1) # (10000, 1)
total_targets = torch.tensor(targets)

2.2 BertTokenizer进行编码,将每一句转成数字

model_name = 'bert-base-chinese'
cache_dir = './sample_data/'

tokenizer = BertTokenizer.from_pretrained(model_name, cache_dir=cache_dir)
print(pos_text[2])
print(tokenizer.tokenize(pos_text[2]))
print(tokenizer.encode(pos_text[2]))
print(tokenizer.convert_ids_to_tokens(tokenizer.encode(pos_text[2])))
不错,下次还考虑入住。交通也方便,在餐厅吃的也不错。

['不', '错', ',', '下', '次', '还', '考', '虑', '入', '住', '。', '交', '通', '也', '方', '便', ',', '在', '餐', '厅', '吃', '的', '也', '不', '错', '。']
[101, 679, 7231, 8024, 678, 3613, 6820, 5440, 5991, 1057, 857, 511, 769, 6858, 738, 3175, 912, 8024, 1762, 7623, 1324, 1391, 4638, 738, 679, 7231, 511, 102]
['[CLS]', '不', '错', ',', '下', '次', '还', '考', '虑', '入', '住', '。', '交', '通', '也', '方', '便', ',', '在', '餐', '厅', '吃', '的', '也', '不', '错', '。', '[SEP]']

为了使每一句的长度相等,稍作处理;

# 将每一句转成数字 (大于126做截断,小于126做 Padding,加上首位两个标识,长度总共等于128)
def convert_text_to_token(tokenizer, sentence, limit_size = 126):
    tokens = tokenizer.encode(sentence[:limit_size])       # 直接截断
    if len(tokens) < limit_size + 2:                       # 补齐(pad的索引号就是0)
        tokens.extend([0] * (limit_size + 2 - len(tokens)))
    return tokens

input_ids = [convert_text_to_token(tokenizer, sen) for sen in sentences]

input_tokens = torch.tensor(input_ids)
print(input_tokens.shape)              # torch.Size([10000, 128])

2.3 attention_masks, 在一个文本中,如果是PAD符号则是0,否则就是1

# 建立mask
def attention_masks(input_ids):
    atten_masks = []
    for seq in input_ids:                       # [10000, 128]
        seq_mask = [float(i > 0) for i in seq]  # PAD: 0; 否则: 1
        atten_masks.append(seq_mask)
    return atten_masks

atten_masks = attention_masks(input_ids)
attention_tokens = torch.tensor(atten_masks)
print(attention_tokens.shape)                   # torch.Size([10000, 128])
  • 构造input_ids 和 atten_masks 的目的 和 前面一节中提到的 .encode_plus函数返回的 input_ids 和 attention_mask 一样

  • input_type_ids 和 本次任务无关,它是针对每个训练集有两个句子的任务(如问答任务)。

2.4 划分训练集和测试集

  • 两个划分函数的参数 random_state 和 test_size 值要一致,才能使得 train_inputs 和 train_masks一一对应。
from sklearn.model_selection import train_test_split

train_inputs, test_inputs, train_labels, test_labels = train_test_split(input_tokens, total_targets, 
                                                                        random_state=666, test_size=0.2)
train_masks, test_masks, _, _ = train_test_split(attention_tokens, input_tokens, 
                                                 random_state=666, test_size=0.2)
print(train_inputs.shape, test_inputs.shape)      # torch.Size([8000, 128]) torch.Size([2000, 128])
print(train_masks.shape)                          # torch.Size([8000, 128])和train_inputs形状一样

print(train_inputs[0])
print(train_masks[0])
torch.Size([8000, 128]) torch.Size([2000, 128])
torch.Size([8000, 128])
tensor([  101,  2769,  6370,  4638,  3221, 10189,  1039,  4638,   117,   852,
         2769,  6230,  2533,  8821,  1039,  4638,  7599,  3419,  3291,  1962,
          671,   763,   117,  3300,   671,  2476,  1377,   809,  1288,  1309,
         4638,  3763,  1355,   119,  2456,  6379,  1920,  2157,  6370,  3249,
         6858,  7313,   106,   102,     0,     0,     0,     0,     0,     0,
            0,     0,     0,     0,     0,     0,     0,     0,     0,     0,
            0,     0,     0,     0,     0,     0,     0,     0,     0,     0,
            0,     0,     0,     0,     0,     0,     0,     0,     0,     0,
            0,     0,     0,     0,     0,     0,     0,     0,     0,     0,
            0,     0,     0,     0,     0,     0,     0,     0,     0,     0,
            0,     0,     0,     0,     0,     0,     0,     0,     0,     0,
            0,     0,     0,     0,     0,     0,     0,     0,     0,     0,
            0,     0,     0,     0,     0,     0,     0,     0])
tensor([1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1.,
        1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1.,
        1., 1., 1., 1., 1., 1., 1., 1., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0.,
        0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0.,
        0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0.,
        0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0.,
        0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0.,
        0., 0.])

2.5 创建DataLoader,用来取出一个batch的数据

  • TensorDataset 可以用来对 tensor 进行打包,就好像 python 中的 zip 功能。

  • 该类通过每一个 tensor 的第一个维度进行索引,所以该类中的 tensor 第一维度必须相等,且TensorDataset 中的参数必须是 tensor类型。

  • RandomSampler:对数据集随机采样。

  • SequentialSampler:按顺序对数据集采样。

train_data = TensorDataset(train_inputs, train_masks, train_labels)
train_sampler = RandomSampler(train_data)
train_dataloader = DataLoader(train_data, sample=train_sampler, batch_size=BATCH_SIZE)

test_data = TensorDataset(test_inputs, test_masks, test_labels)
test_sampler = RandomSampler(test_data)
test_dataloader = DataLoader(test_data, sampler=test_sampler, batch_size=BATCH_SIZE)

查看一下train_dataloader的内容:

for i, (train, mask, label) in enumerate(train_dataloader): 
    # torch.Size([16, 128]) torch.Size([16, 128]) torch.Size([16, 1])
    print(train.shape, mask.shape, label.shape)
    break

print('len(train_dataloader) = ', len(train_dataloader))    # 500

3. 创建模型、优化器


3.1 创建模型

model = BertForSequenceClassification.from_pretrained(model_name, num_labels = 2) # num_labels表示2个分类,好评和差评
device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
model.to(device)

BertForSequenceClassification(
  (bert): BertModel(
    (embeddings): BertEmbeddings(
      (word_embeddings): Embedding(21128, 768, padding_idx=0)
      (position_embeddings): Embedding(512, 768)
      (token_type_embeddings): Embedding(2, 768)
      (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
      (dropout): Dropout(p=0.1, inplace=False)
    )
    (encoder): BertEncoder(
      (layer): ModuleList(
        (0): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
        (1): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
        (2): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
        (3): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
        (4): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
        (5): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
        (6): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
        (7): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
        (8): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
        (9): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
        (10): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
        (11): BertLayer(
          (attention): BertAttention(
            (self): BertSelfAttention(
              (query): Linear(in_features=768, out_features=768, bias=True)
              (key): Linear(in_features=768, out_features=768, bias=True)
              (value): Linear(in_features=768, out_features=768, bias=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
            (output): BertSelfOutput(
              (dense): Linear(in_features=768, out_features=768, bias=True)
              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
              (dropout): Dropout(p=0.1, inplace=False)
            )
          )
          (intermediate): BertIntermediate(
            (dense): Linear(in_features=768, out_features=3072, bias=True)
          )
          (output): BertOutput(
            (dense): Linear(in_features=3072, out_features=768, bias=True)
            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)
            (dropout): Dropout(p=0.1, inplace=False)
          )
        )
      )
    )
    (pooler): BertPooler(
      (dense): Linear(in_features=768, out_features=768, bias=True)
      (activation): Tanh()
    )
  )
  (dropout): Dropout(p=0.1, inplace=False)
  (classifier): Linear(in_features=768, out_features=2, bias=True)
)

3.2 定义优化器

参数eps是为了 提高数值稳定性 而添加到分母的一个项(默认: 1e-8)。

optimizer = AdamW(model.parameters(), lr = learning_rate, eps = epsilon)

更通用的写法:bias和LayNorm.weight没有用权重衰减

no_decay = ['bias', 'LayerNorm.weight']
optimizer_grouped_parameters = [
    {'params' : [p for n, p in model.named_parameters() if not any(nd in n for nd in no_decay)],
     'weight_decay' : weight_decay
    },
    {'params' : [p for n, p in model.named_parameters() if any(nd in n for nd in no_decay)],
     'weight_decay' : 0.0
    }
]

optimizer = AdamW(optimizer_grouped_parameters, lr = learning_rate, eps = epsilon)

3.3 学习率预热,训练时先从小的学习率开始训练

epochs = 2
# training steps 的数量: [number of batches] x [number of epochs].
total_steps = len(train_dataloader) * epochs

# 设计 learning rate scheduler.
scheduler = get_linear_schedule_with_warmup(optimizer, num_warmup_steps = 0, 
                                            num_training_steps = total_steps)

4.训练、评估模型

4.1 模型准确率

def binary_acc(preds, labels): # preds.shape = [16, 2] labels.shape = [16, 1]
    # torch.max: [0]为最大值, [1]为最大值索引
    correct = torch.eq(torch.max(preds, dim=1)[1], labels.flatten()).float()
    acc = correct.sum().item() / len(correct)
    return acc

4.2 计算模型运行时间

import time
import datetime

def format_time(elapsed):
    elapsed_rounded = int(round(elapsed))
    return str(datetime.timedelta(seconds = elapsed_rounded)) # 返回 hh:mm:ss 形式的时间

4.3 训练模型

  • 传入model的参数必须是tensor类型的;

  • nn.utils.clip_grad_norm_(parameters, max_norm, norm_type=2) 用于解决神经网络训练过拟合的方法;

    • 输入是(NN参数,最大梯度范数,范数类型=2) 一般默认为L2 范数;

    • Tip: 注意这个方法只在训练的时候使用,在测试的时候不用;

def train(model, optimizer):
    t0 = time.time()
    avg_loss, avg_acc = [],[]

    model.train()
    for step, batch in enumerate(train_dataloader):

        # 每隔40个batch 输出一下所用时间.
        if step % 40 == 0 and not step == 0:
            elapsed = format_time(time.time() - t0)
            print('  Batch {:>5,}  of  {:>5,}.    Elapsed: {:}.'.format(step, len(train_dataloader), elapsed))

        b_input_ids, b_input_mask, b_labels = batch[0].long().to(device), batch[1].long().to(device), batch[2].long().to(device)

        output = model(b_input_ids, token_type_ids=None, attention_mask=b_input_mask, labels=b_labels)
        loss, logits = output[0], output[1]      # loss: 损失, logits: predict

        avg_loss.append(loss.item())

        acc = binary_acc(logits, b_labels)       # (predict, label)
        avg_acc.append(acc)

        optimizer.zero_grad()
        loss.backward()
        clip_grad_norm_(model.parameters(), 1.0) # 大于1的梯度将其设为1.0, 以防梯度爆炸
        optimizer.step()                         # 更新模型参数
        scheduler.step()                         # 更新learning rate

    avg_acc = np.array(avg_acc).mean()
    avg_loss = np.array(avg_loss).mean()
    return avg_loss, avg_acc
  • 此处 output的形式为(元组类型,第0个元素是loss值,第1个元素是每个batch中好评和差评的概率):
(tensor(0.0210, device='cuda:0', grad_fn=), 
tensor([[-2.9815,  2.6931],
        [-3.2380,  3.1935],
        [-3.0775,  3.0713],
        [ 3.0191, -2.3689],
        [ 3.1146, -2.7957],
        [ 3.7798, -2.7410],
        [-0.3273,  0.8227],
        [ 2.5012, -1.5535],
        [-3.0231,  3.0162],
        [ 3.4146, -2.5582],
        [ 3.3104, -2.2134],
        [ 3.3776, -2.5190],
        [-2.6513,  2.5108],
        [-3.3691,  2.9516],
        [ 3.2397, -2.0473],
        [-2.8622,  2.7395]], device='cuda:0', grad_fn=))

4.4 评估模型

调用model模型时不传入label值。

def evaluate(model):
    avg_acc = []
    model.eval()         # 表示进入测试模式

    with torch.no_grad():
        for batch in test_dataloader:
            b_input_ids, b_input_mask, b_labels = batch[0].long().to(device), batch[1].long().to(device), batch[2].long().to(device)

            output = model(b_input_ids, token_type_ids=None, attention_mask=b_input_mask)

            acc = binary_acc(output[0], b_labels)
            avg_acc.append(acc)

    avg_acc = np.array(avg_acc).mean()
    return avg_acc

此处output的形式为(元组类型,第0个元素是每个batch中好评和差评的概率):(区别写label的model)

(tensor([[ 3.8217, -2.7516],
        [ 2.7585, -2.0853],
        [-2.9317,  2.9092],
        [-3.3724,  3.2597],
        [-2.8692,  2.6741],
        [-3.2784,  2.9276],
        [ 3.4946, -2.8895],
        [ 3.7855, -2.8623],
        [-2.2249,  2.4336],
        [-2.4257,  2.4606],
        [ 3.3996, -2.5760],
        [-3.1986,  3.0841],
        [ 3.6883, -2.9492],
        [ 3.2883, -2.3600],
        [ 2.6723, -2.0778],
        [-3.1868,  3.1106]], device='cuda:0'),)

4.5 运行训练模型和评估模型

for epoch in range(epochs):

    train_loss, train_acc = train(model, optimizer)
    print('epoch={},训练准确率={},损失={}'.format(epoch, train_acc, train_loss))
    
    test_acc = evaluate(model)
    print("epoch={},测试准确率={}".format(epoch, test_acc))

 Batch    40  of    500.    Elapsed: 0:00:27.
  Batch    80  of    500.    Elapsed: 0:00:53.
  Batch   120  of    500.    Elapsed: 0:01:20.
  Batch   160  of    500.    Elapsed: 0:01:47.
  Batch   200  of    500.    Elapsed: 0:02:14.
  Batch   240  of    500.    Elapsed: 0:02:40.
  Batch   280  of    500.    Elapsed: 0:03:07.
  Batch   320  of    500.    Elapsed: 0:03:34.
  Batch   360  of    500.    Elapsed: 0:04:01.
  Batch   400  of    500.    Elapsed: 0:04:28.
  Batch   440  of    500.    Elapsed: 0:04:55.
  Batch   480  of    500.    Elapsed: 0:05:22.
epoch=0,训练准确率=0.90275,损失=0.2619755164962262
epoch=0,测试准确率=0.9325
  Batch    40  of    500.    Elapsed: 0:00:27.
  Batch    80  of    500.    Elapsed: 0:00:53.
  Batch   120  of    500.    Elapsed: 0:01:20.
  Batch   160  of    500.    Elapsed: 0:01:47.
  Batch   200  of    500.    Elapsed: 0:02:14.
  Batch   240  of    500.    Elapsed: 0:02:41.
  Batch   280  of    500.    Elapsed: 0:03:08.
  Batch   320  of    500.    Elapsed: 0:03:35.
  Batch   360  of    500.    Elapsed: 0:04:02.
  Batch   400  of    500.    Elapsed: 0:04:28.
  Batch   440  of    500.    Elapsed: 0:04:55.
  Batch   480  of    500.    Elapsed: 0:05:22.
epoch=1,训练准确率=0.953375,损失=0.15345162890665234
epoch=1,测试准确率=0.9435

5. 预测

def predict(sen):

    input_id = convert_text_to_token(tokenizer, sen)
    input_token =  torch.tensor(input_id).long().to(device)            #torch.Size([128])

    atten_mask = [float(i>0) for i in input_id]
    attention_token = torch.tensor(atten_mask).long().to(device)       #torch.Size([128])

    output = model(input_token.view(1, -1), token_type_ids=None, attention_mask=attention_token.view(1, -1))     #torch.Size([128])->torch.Size([1, 128])否则会报错
    print(output[0])

    return torch.max(output[0], dim=1)[1]

label = predict('酒店位置难找,环境不太好,隔音差,下次不会再来的。')
print('好评' if label==1 else '差评')

label = predict('酒店还可以,接待人员很热情,卫生合格,空间也比较大,不足的地方就是没有窗户')
print('好评' if label==1 else '差评')

label = predict('"服务各方面没有不周到的地方, 各方面没有没想到的细节"')
print('好评' if label==1 else '差评')
tensor([[ 2.3774, -4.0351]], device='cuda:0', grad_fn=)
差评
tensor([[-2.5653,  2.7316]], device='cuda:0', grad_fn=)
好评
tensor([[-2.0390,  1.6002]], device='cuda:0', grad_fn=)
好评

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