用python基于神经网络的THUCNews数据集文本分类

好的，我可以给你提供一个基于神经网络的THUCNews数据集文本分类的Python实现。

首先，我们需要下载THUCNews数据集。可以在清华大学开源软件镜像站上下载，链接为：https://mirror.tuna.tsinghua.edu.cn/thulac/data/THUCNews.zip。

接下来，我们需要对数据进行预处理。我们可以使用Python中的jieba库进行中文分词，然后将分词结果转化成数字形式。代码如下所示：

import jieba
import os
import numpy as np

# 加载停用词
stopwords = []
with open('stopwords.txt', 'r', encoding='utf-8') as f:
    for line in f:
        stopwords.append(line.strip())

# 对文本进行分词和数字化处理
def preprocess_text(text, word_to_id, max_length):
    words = jieba.cut(text)
    words = [word for word in words if word not in stopwords]
    words = [word_to_id[word] if word in word_to_id else 0 for word in words]
    if len(words) < max_length:
        words += [0] * (max_length - len(words))
    else:
        words = words[:max_length]
    return np.array(words)

接下来，我们需要将文本数据转化成数字形式。我们可以先将所有文本中的单词统计出来，然后根据单词出现次数进行排序，将出现频率最高的前N个单词作为我们的词汇表。代码如下所示：

# 构建词汇表
def build_vocab(data_path, vocab_path, vocab_size):
    word_to_count = {}
    with open(data_path, 'r', encoding='utf-8') as f:
        for line in f:
            line = line.strip().split('\t')
            if len(line) != 2:
                continue
            words = jieba.cut(line[1])
            for word in words:
                if word not in word_to_count:
                    word_to_count[word] = 0
                word_to_count[word] += 1

    sorted_words = sorted(word_to_count.items(), key=lambda x: x[1], reverse=True)

    # 取出现频率最高的前vocab_size个单词
    vocab = ['<PAD>', '<UNK>'] + [x[0] for x in sorted_words[:vocab_size - 2]]
    with open(vocab_path, 'w', encoding='utf-8') as f:
        f.write('\n'.join(vocab))

接下来，我们可以将所有文本数据转化成数字形式。代码如下所示：

# 将数据转化成数字形式
def convert_data_to_id(data_path, vocab_path, max_length):
    with open(vocab_path, 'r', encoding='utf-8') as f:
        vocab = [line.strip() for line in f]

    word_to_id = {word: i for i, word in enumerate(vocab)}
    labels = []
    texts = []
    with open(data_path, 'r', encoding='utf-8') as f:
        for line in f:
            line = line.strip().split('\t')
            if len(line) != 2:
                continue
            label = int(line[0])
            text = preprocess_text(line[1], word_to_id, max_length)
            labels.append(label)
            texts.append(text)

    return np.array(labels), np.array(texts)

接下来，我们可以定义神经网络模型。这里我们使用一个简单的卷积神经网络，代码如下所示：

import tensorflow as tf

# 定义卷积神经网络模型
def cnn_model(inputs, num_classes, vocab_size, embedding_size, filter_sizes, num_filters):
    # Embedding Layer
    with tf.name_scope("embedding"):
        W = tf.Variable(tf.random_uniform([vocab_size, embedding_size], -1.0, 1.0), name="W")
        embedded_chars = tf.nn.embedding_lookup(W, inputs)
        embedded_chars_expanded = tf.expand_dims(embedded_chars, -1)

    # Convolution and Max Pooling Layers
    pooled_outputs = []
    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]
            W = tf.Variable(tf.truncated_normal(filter_shape, stddev=0.1), name="W")
            b = tf.Variable(tf.constant(0.1, shape=[num_filters]), name="b")
            conv = tf.nn.conv2d(embedded_chars_expanded, W, strides=[1, 1, 1, 1], padding="VALID", name="conv")
            # Activation Function
            h = tf.nn.relu(tf.nn.bias_add(conv, b), name="relu")
            # Max Pooling Layer
            pooled = tf.nn.max_pool(h, ksize=[1, inputs.shape[1] - filter_size + 1, 1, 1], strides=[1, 1, 1, 1], padding="VALID", name="pool")
            pooled_outputs.append(pooled)

    # Combine All Pooled Features
    num_filters_total = num_filters * len(filter_sizes)
    h_pool = tf.concat(pooled_outputs, 3)
    h_pool_flat = tf.reshape(h_pool, [-1, num_filters_total])

    # Dropout Layer
    with tf.name_scope("dropout"):
        keep_prob = tf.placeholder(tf.float32, name="keep_prob")
        h_drop = tf.nn.dropout(h_pool_flat, keep_prob)

    # Output Layer
    with tf.name_scope("output"):
        W = tf.Variable(tf.truncated_normal([num_filters_total, num_classes], stddev=0.1), name="W")
        b = tf.Variable(tf.constant(0.1, shape=[num_classes]), name="b")
        scores = tf.nn.xw_plus_b(h_drop, W, b, name="scores")

    return scores, keep_prob

接下来，我们可以定义训练函数。代码如下所示：

# 训练函数
def train(data_path, vocab_path, model_path, num_classes, vocab_size, max_length, embedding_size, filter_sizes, num_filters, batch_size, num_epochs, learning_rate):
    # 加载数据
    labels, texts = convert_data_to_id(data_path, vocab_path, max_length)

    # 划分训练集和测试集
    num_samples = len(labels)
    indices = np.random.permutation(num_samples)
    train_indices = indices[:int(num_samples * 0.8)]
    test_indices = indices[int(num_samples * 0.8):]
    train_labels = labels[train_indices]
    test_labels = labels[test_indices]
    train_texts = texts[train_indices]
    test_texts = texts[test_indices]

    # 定义模型
    inputs = tf.placeholder(tf.int32, [None, max_length], name="inputs")
    labels = tf.placeholder(tf.int32, [None], name="labels")
    logits, keep_prob = cnn_model(inputs, num_classes, vocab_size, embedding_size, filter_sizes, num_filters)

    # 定义损失函数和优化器
    with tf.name_scope("loss"):
        loss = tf.reduce_mean(tf.nn.sparse_softmax_cross_entropy_with_logits(logits=logits, labels=labels))
    with tf.name_scope("optimizer"):
        optimizer = tf.train.AdamOptimizer(learning_rate)
        grads_and_vars = optimizer.compute_gradients(loss)
        train_op = optimizer.apply_gradients(grads_and_vars)

    # 定义评估指标
    with tf.name_scope("accuracy"):
        correct_predictions = tf.equal(tf.argmax(logits, 1), tf.cast(labels, tf.int64))
        accuracy = tf.reduce_mean(tf.cast(correct_predictions, tf.float32))

    # 训练模型
    with tf.Session() as sess:
        sess.run(tf.global_variables_initializer())
        for epoch in range(num_epochs):
            train_loss = 0.0
            train_acc = 0.0
            num_batches = int(len(train_labels) / batch_size)
            for i in range(num_batches):
                batch_labels = train_labels[i * batch_size:(i + 1) * batch_size]
                batch_texts = train_texts[i * batch_size:(i + 1) * batch_size]
                _, batch_loss, batch_acc = sess.run([train_op, loss, accuracy], feed_dict={inputs: batch_texts, labels: batch_labels, keep_prob: 0.5})
                train_loss += batch_loss
                train_acc += batch_acc
            train_loss /= num_batches
            train_acc /= num_batches

            test_loss, test_acc = sess.run([loss, accuracy], feed_dict={inputs: test_texts, labels: test_labels, keep_prob: 1.0})

            print("Epoch %d: train_loss=%.4f, train_acc=%.4f, test_loss=%.4f, test_acc=%.4f" % (epoch + 1, train_loss, train_acc, test_loss, test_acc))

        # 保存模型
        saver = tf.train.Saver()
        saver.save(sess, model_path)

最后，我们可以调用训练函数进行训练。代码如下所示：

data_path = 'THUCNews/THUCNews_train.txt'
vocab_path = 'vocab.txt'
model_path = 'model.ckpt'
num_classes = 14
vocab_size = 50000
max_length = 200
embedding_size = 128
filter_sizes = [2, 3, 4]
num_filters = 128
batch_size = 64
num_epochs = 10
learning_rate = 1e-3

# 构建词汇表
build_vocab(data_path, vocab_path, vocab_size)

# 训练模型
train(data_path, vocab_path, model_path, num_classes, vocab_size, max_length, embedding_size, filter_sizes, num_filters, batch_size, num_epochs, learning_rate)

这样，我们就完成了一个基于神经网络的THUCNews数据集文本分类的Python实现。