欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  IT编程

Tensorflow深度学习使用CNN分类英文文本

程序员文章站 2022-03-15 20:40:56
目录前言源码与数据源码数据train.py 源码及分析data_helpers.py 源码及分析text_cnn.py 源码及分析前言github源码地址 本文同时也是学习唐宇迪老师深度学习课程的一些...

前言

github源码地址

本文同时也是学习唐宇迪老师深度学习课程的一些理解与记录。

文中代码是实现在tensorflow下使用卷积神经网络(cnn)做英文文本的分类任务(本次是垃圾邮件的二分类任务),当然垃圾邮件分类是一种应用环境,模型方法也可以推广到其它应用场景,如电商商品好评差评分类、正负面新闻等。

Tensorflow深度学习使用CNN分类英文文本

源码与数据

源码

- data_helpers.py

- train.py

- text_cnn.py

- eval.py(save the evaluations to a csv, in case the user wants to inspect,analyze, or otherwise use the classifications generated by the neural net)

数据

- rt-polarity.neg

- rt-polarity.pos

Tensorflow深度学习使用CNN分类英文文本

Tensorflow深度学习使用CNN分类英文文本

train.py 源码及分析

import tensorflow as tf
import numpy as np
import os
import time
import datetime
import data_helpers
from text_cnn import textcnn
from tensorflow.contrib import learn
# parameters
# ==================================================
# data loading params
# 语料文件路径定义
tf.flags.define_float("dev_sample_percentage", .1, "percentage of the training data to use for validation")
tf.flags.define_string("positive_data_file", "./data/rt-polaritydata/rt-polarity.pos", "data source for the positive data.")
tf.flags.define_string("negative_data_file", "./data/rt-polaritydata/rt-polarity.neg", "data source for the negative data.")

# model hyperparameters
# 定义网络超参数
tf.flags.define_integer("embedding_dim", 128, "dimensionality of character embedding (default: 128)")
tf.flags.define_string("filter_sizes", "3,4,5", "comma-separated filter sizes (default: '3,4,5')")
tf.flags.define_integer("num_filters", 128, "number of filters per filter size (default: 128)")
tf.flags.define_float("dropout_keep_prob", 0.5, "dropout keep probability (default: 0.5)")
tf.flags.define_float("l2_reg_lambda", 0.0, "l2 regularization lambda (default: 0.0)")

# training parameters
# 训练参数
tf.flags.define_integer("batch_size", 32, "batch size (default: 32)")
tf.flags.define_integer("num_epochs", 200, "number of training epochs (default: 200)") # 总训练次数
tf.flags.define_integer("evaluate_every", 100, "evaluate model on dev set after this many steps (default: 100)") # 每训练100次测试一下
tf.flags.define_integer("checkpoint_every", 100, "save model after this many steps (default: 100)") # 保存一次模型
tf.flags.define_integer("num_checkpoints", 5, "number of checkpoints to store (default: 5)")
# misc parameters
tf.flags.define_boolean("allow_soft_placement", true, "allow device soft device placement") # 加上一个布尔类型的参数,要不要自动分配
tf.flags.define_boolean("log_device_placement", false, "log placement of ops on devices") # 加上一个布尔类型的参数,要不要打印日志

# 打印一下相关初始参数
flags = tf.flags.flags
flags._parse_flags()
print("\nparameters:")
for attr, value in sorted(flags.__flags.items()):
    print("{}={}".format(attr.upper(), value))
print("")

# data preparation
# ==================================================
# load data
print("loading data...")
x_text, y = data_helpers.load_data_and_labels(flags.positive_data_file, flags.negative_data_file)
# build vocabulary
max_document_length = max([len(x.split(" ")) for x in x_text]) # 计算最长邮件
vocab_processor = learn.preprocessing.vocabularyprocessor(max_document_length) # tensorflow提供的工具,将数据填充为最大长度,默认0填充
x = np.array(list(vocab_processor.fit_transform(x_text)))

# randomly shuffle data
# 数据洗牌
np.random.seed(10)
# np.arange生成随机序列
shuffle_indices = np.random.permutation(np.arange(len(y)))
x_shuffled = x[shuffle_indices]
y_shuffled = y[shuffle_indices]

# 将数据按训练train和测试dev分块
# split train/test set
# todo: this is very crude, should use cross-validation
dev_sample_index = -1 * int(flags.dev_sample_percentage * float(len(y)))
x_train, x_dev = x_shuffled[:dev_sample_index], x_shuffled[dev_sample_index:]
y_train, y_dev = y_shuffled[:dev_sample_index], y_shuffled[dev_sample_index:]
print("vocabulary size: {:d}".format(len(vocab_processor.vocabulary_)))
print("train/dev split: {:d}/{:d}".format(len(y_train), len(y_dev))) # 打印切分的比例
# training
# ==================================================
with tf.graph().as_default():
    session_conf = tf.configproto(
        allow_soft_placement=flags.allow_soft_placement,
        log_device_placement=flags.log_device_placement)
    sess = tf.session(config=session_conf)
    with sess.as_default():
        # 卷积池化网络导入
        cnn = textcnn(
            sequence_length=x_train.shape[1],
            num_classes=y_train.shape[1], # 分几类
            vocab_size=len(vocab_processor.vocabulary_),
            embedding_size=flags.embedding_dim,
            filter_sizes=list(map(int, flags.filter_sizes.split(","))), # 上面定义的filter_sizes拿过来,"3,4,5"按","分割
            num_filters=flags.num_filters, # 一共有几个filter
            l2_reg_lambda=flags.l2_reg_lambda) # l2正则化项

        # define training procedure
        global_step = tf.variable(0, name="global_step", trainable=false)
        optimizer = tf.train.adamoptimizer(1e-3) # 定义优化器
        grads_and_vars = optimizer.compute_gradients(cnn.loss)
        train_op = optimizer.apply_gradients(grads_and_vars, global_step=global_step)

        # keep track of gradient values and sparsity (optional)
        grad_summaries = []
        for g, v in grads_and_vars:
            if g is not none:
                grad_hist_summary = tf.summary.histogram("{}/grad/hist".format(v.name), g)
                sparsity_summary = tf.summary.scalar("{}/grad/sparsity".format(v.name), tf.nn.zero_fraction(g))
                grad_summaries.append(grad_hist_summary)
                grad_summaries.append(sparsity_summary)
        grad_summaries_merged = tf.summary.merge(grad_summaries)

        # output directory for models and summaries
        timestamp = str(int(time.time()))
        out_dir = os.path.abspath(os.path.join(os.path.curdir, "runs", timestamp))
        print("writing to {}\n".format(out_dir))

        # summaries for loss and accuracy
        # 损失函数和准确率的参数保存
        loss_summary = tf.summary.scalar("loss", cnn.loss)
        acc_summary = tf.summary.scalar("accuracy", cnn.accuracy)

        # train summaries
        # 训练数据保存
        train_summary_op = tf.summary.merge([loss_summary, acc_summary, grad_summaries_merged])
        train_summary_dir = os.path.join(out_dir, "summaries", "train")
        train_summary_writer = tf.summary.filewriter(train_summary_dir, sess.graph)

        # dev summaries
        # 测试数据保存
        dev_summary_op = tf.summary.merge([loss_summary, acc_summary])
        dev_summary_dir = os.path.join(out_dir, "summaries", "dev")
        dev_summary_writer = tf.summary.filewriter(dev_summary_dir, sess.graph)

        # checkpoint directory. tensorflow assumes this directory already exists so we need to create it
        checkpoint_dir = os.path.abspath(os.path.join(out_dir, "checkpoints"))
        checkpoint_prefix = os.path.join(checkpoint_dir, "model")
        if not os.path.exists(checkpoint_dir):
            os.makedirs(checkpoint_dir)

        saver = tf.train.saver(tf.global_variables(), max_to_keep=flags.num_checkpoints) # 前面定义好参数num_checkpoints

        # write vocabulary
        vocab_processor.save(os.path.join(out_dir, "vocab"))

        # initialize all variables
        sess.run(tf.global_variables_initializer()) # 初始化所有变量

        # 定义训练函数
        def train_step(x_batch, y_batch):
            """
            a single training step
            """
            feed_dict = {
              cnn.input_x: x_batch,
              cnn.input_y: y_batch,
              cnn.dropout_keep_prob: flags.dropout_keep_prob # 参数在前面有定义
            }
            _, step, summaries, loss, accuracy = sess.run(
                [train_op, global_step, train_summary_op, cnn.loss, cnn.accuracy], feed_dict)
            time_str = datetime.datetime.now().isoformat() # 取当前时间,python的函数
            print("{}: step {}, loss {:g}, acc {:g}".format(time_str, step, loss, accuracy))
            train_summary_writer.add_summary(summaries, step)

        # 定义测试函数
        def dev_step(x_batch, y_batch, writer=none):
            """
            evaluates model on a dev set
            """
            feed_dict = {
              cnn.input_x: x_batch,
              cnn.input_y: y_batch,
              cnn.dropout_keep_prob: 1.0 # 神经元全部保留
            }
            step, summaries, loss, accuracy = sess.run(
                [global_step, dev_summary_op, cnn.loss, cnn.accuracy], feed_dict)
            time_str = datetime.datetime.now().isoformat()
            print("{}: step {}, loss {:g}, acc {:g}".format(time_str, step, loss, accuracy))
            if writer:
                writer.add_summary(summaries, step)

        # generate batches
        batches = data_helpers.batch_iter(list(zip(x_train, y_train)), flags.batch_size, flags.num_epochs)
        # training loop. for each batch...
        # 训练部分
        for batch in batches:
            x_batch, y_batch = zip(*batch) # 按batch把数据拿进来
            train_step(x_batch, y_batch)
            current_step = tf.train.global_step(sess, global_step) # 将session和global_step值传进来
            if current_step % flags.evaluate_every == 0: # 每flags.evaluate_every次每100执行一次测试
                print("\nevaluation:")
                dev_step(x_dev, y_dev, writer=dev_summary_writer)
                print("")
            if current_step % flags.checkpoint_every == 0: # 每checkpoint_every次执行一次保存模型
                path = saver.save(sess, './', global_step=current_step) # 定义模型保存路径
                print("saved model checkpoint to {}\n".format(path))

data_helpers.py 源码及分析

import numpy as np
import re
import itertools
from collections import counter

def clean_str(string):
    """
    tokenization/string cleaning for all datasets except for sst.
    original taken from https://github.com/yoonkim/cnn_sentence/blob/master/process_data.py
    """
    # 清理数据替换掉无词义的符号
    string = re.sub(r"[^a-za-z0-9(),!?\'\`]", " ", string)
    string = re.sub(r"\'s", " \'s", string)
    string = re.sub(r"\'ve", " \'ve", string)
    string = re.sub(r"n\'t", " n\'t", string)
    string = re.sub(r"\'re", " \'re", string)
    string = re.sub(r"\'d", " \'d", string)
    string = re.sub(r"\'ll", " \'ll", string)
    string = re.sub(r",", " , ", string)
    string = re.sub(r"!", " ! ", string)
    string = re.sub(r"\(", " \( ", string)
    string = re.sub(r"\)", " \) ", string)
    string = re.sub(r"\?", " \? ", string)
    string = re.sub(r"\s{2,}", " ", string)
    return string.strip().lower()
def load_data_and_labels(positive_data_file, negative_data_file):
    """
    loads mr polarity data from files, splits the data into words and generates labels.
    returns split sentences and labels.
    """
    # load data from files
    positive = open(positive_data_file, "rb").read().decode('utf-8')
    negative = open(negative_data_file, "rb").read().decode('utf-8')

    # 按回车分割样本
    positive_examples = positive.split('\n')[:-1]
    negative_examples = negative.split('\n')[:-1]

    # 去空格
    positive_examples = [s.strip() for s in positive_examples]
    negative_examples = [s.strip() for s in negative_examples]

    #positive_examples = list(open(positive_data_file, "rb").read().decode('utf-8'))
    #positive_examples = [s.strip() for s in positive_examples]
    #negative_examples = list(open(negative_data_file, "rb").read().decode('utf-8'))
    #negative_examples = [s.strip() for s in negative_examples]
    # split by words
    x_text = positive_examples + negative_examples
    x_text = [clean_str(sent) for sent in x_text] # 字符过滤,实现函数见clean_str()
    # generate labels
    positive_labels = [[0, 1] for _ in positive_examples]
    negative_labels = [[1, 0] for _ in negative_examples]
    y = np.concatenate([positive_labels, negative_labels], 0) # 将两种label连在一起
    return [x_text, y]

# 创建batch迭代模块
def batch_iter(data, batch_size, num_epochs, shuffle=true): # shuffle=true洗牌
    """
    generates a batch iterator for a dataset.
    """
    # 每次只输出shuffled_data[start_index:end_index]这么多
    data = np.array(data)
    data_size = len(data)
    num_batches_per_epoch = int((len(data)-1)/batch_size) + 1 # 每一个epoch有多少个batch_size
    for epoch in range(num_epochs):
        # shuffle the data at each epoch
        if shuffle:
            shuffle_indices = np.random.permutation(np.arange(data_size)) # 洗牌
            shuffled_data = data[shuffle_indices]
        else:
            shuffled_data = data
        for batch_num in range(num_batches_per_epoch):
            start_index = batch_num * batch_size # 当前batch的索引开始
            end_index = min((batch_num + 1) * batch_size, data_size) # 判断下一个batch是不是超过最后一个数据了
            yield shuffled_data[start_index:end_index]

text_cnn.py 源码及分析

import tensorflow as tf
import numpy as np
# 定义cnn网络实现的类
class textcnn(object):
    """
    a cnn for text classification.
    uses an embedding layer, followed by a convolutional, max-pooling and softmax layer.
    """
    def __init__(self, sequence_length, num_classes, vocab_size,
                 embedding_size, filter_sizes, num_filters, l2_reg_lambda=0.0): # 把train.py中textcnn里定义的参数传进来

        # placeholders for input, output and dropout
        self.input_x = tf.placeholder(tf.int32, [none, sequence_length], name="input_x") # input_x输入语料,待训练的内容,维度是sequence_length,"n个词构成的n维向量"
        self.input_y = tf.placeholder(tf.float32, [none, num_classes], name="input_y") # input_y输入语料,待训练的内容标签,维度是num_classes,"正面 || 负面"
        self.dropout_keep_prob = tf.placeholder(tf.float32, name="dropout_keep_prob") # dropout_keep_prob dropout参数,防止过拟合,训练时用
        # keeping track of l2 regularization loss (optional)
        l2_loss = tf.constant(0.0) # 先不用,写0
        # embedding layer
        # 指定运算结构的运行位置在cpu非gpu,因为"embedding"无法运行在gpu
        # 通过tf.name_scope指定"embedding"
        with tf.device('/cpu:0'), tf.name_scope("embedding"): # 指定cpu
            self.w = tf.variable(tf.random_uniform([vocab_size, embedding_size], -1.0, 1.0), name="w") # 定义w并初始化
            self.embedded_chars = tf.nn.embedding_lookup(self.w, self.input_x)
            self.embedded_chars_expanded = tf.expand_dims(self.embedded_chars, -1) # 加一个维度,转换为4维的格式
        # create a convolution + maxpool layer for each filter size
        pooled_outputs = []
        # filter_sizes卷积核尺寸,枚举后遍历
        for i, filter_size in enumerate(filter_sizes):
            with tf.name_scope("conv-maxpool-%s" % filter_size):
                # convolution layer
                filter_shape = [filter_size, embedding_size, 1, num_filters] # 4个参数分别为filter_size高h,embedding_size宽w,channel为1,filter个数
                w = tf.variable(tf.truncated_normal(filter_shape, stddev=0.1), name="w") # w进行高斯初始化
                b = tf.variable(tf.constant(0.1, shape=[num_filters]), name="b") # b给初始化为一个常量
                conv = tf.nn.conv2d(
                    self.embedded_chars_expanded,
                    w,
                    strides=[1, 1, 1, 1],
                    padding="valid", # 这里不需要padding
                    name="conv")
                # apply nonlinearity 激活函数
                # 可以理解为,正面或者负面评价有一些标志词汇,这些词汇概率被增强,即一旦出现这些词汇,倾向性分类进正或负面评价,
                # 该激励函数可加快学习进度,增加稀疏性,因为让确定的事情更确定,噪声的影响就降到了最低。
                h = tf.nn.relu(tf.nn.bias_add(conv, b), name="relu")
                # maxpooling over the outputs
                # 池化
                pooled = tf.nn.max_pool(
                    h,
                    ksize=[1, sequence_length - filter_size + 1, 1, 1], # (h-filter+2padding)/strides+1=h-f+1
                    strides=[1, 1, 1, 1],
                    padding='valid', # 这里不需要padding
                    name="pool")
                pooled_outputs.append(pooled)

        # combine all the pooled features
        num_filters_total = num_filters * len(filter_sizes)
        self.h_pool = tf.concat(3, pooled_outputs)
        self.h_pool_flat = tf.reshape(self.h_pool, [-1, num_filters_total]) # 扁平化数据,跟全连接层相连
        # add dropout
        # drop层,防止过拟合,参数为dropout_keep_prob
        # 过拟合的本质是采样失真,噪声权重影响了判断,如果采样足够多,足够充分,噪声的影响可以被量化到趋近事实,也就无从过拟合。
        # 即数据越大,drop和正则化就越不需要。
        with tf.name_scope("dropout"):
            self.h_drop = tf.nn.dropout(self.h_pool_flat, self.dropout_keep_prob)

        # final (unnormalized) scores and predictions
        # 输出层
        with tf.name_scope("output"):
            w = tf.get_variable(
                "w",
                shape=[num_filters_total, num_classes], #前面连扁平化后的池化操作
                initializer=tf.contrib.layers.xavier_initializer()) # 定义初始化方式
            b = tf.variable(tf.constant(0.1, shape=[num_classes]), name="b")
            # 损失函数导入
            l2_loss += tf.nn.l2_loss(w)
            l2_loss += tf.nn.l2_loss(b)
            # xw+b
            self.scores = tf.nn.xw_plus_b(self.h_drop, w, b, name="scores") # 得分函数
            self.predictions = tf.argmax(self.scores, 1, name="predictions") # 预测结果

        # calculatemean cross-entropy loss
        with tf.name_scope("loss"):
            # loss,交叉熵损失函数
            losses = tf.nn.softmax_cross_entropy_with_logits(logits=self.scores, labels=self.input_y)
            self.loss = tf.reduce_mean(losses) + l2_reg_lambda * l2_loss

        # accuracy
        with tf.name_scope("accuracy"):
            # 准确率,求和计算算数平均值
            correct_predictions = tf.equal(self.predictions, tf.argmax(self.input_y, 1))
            self.accuracy = tf.reduce_mean(tf.cast(correct_predictions, "float"), name="accuracy")

Tensorflow深度学习使用CNN分类英文文本

以上就是tensorflow深度学习cnn实现英文文本分类的详细内容,更多关于tensorflow实现cnn分类英文文本的资料请关注其它相关文章!