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# -*- coding: utf-8 -*-
"""
配置文件 - 所有超参数集中管理
设计思路:
将超参数分门别类,学生可以单独修改某一类而不会影响其他
"""
# ==================== 数据相关 ====================
DATA_DIR = 'data/ChnSentiCorp' # 数据集路径
MAX_FEATURES = 3000 # 词表最大容量
MAX_SEQ_LEN = 100 # 句子最大长度(词数)
VECTORIZER_TYPE = 'tfidf' # 'tfidf' 或 'bow'(向量化方式)
# ==================== 模型相关 ====================
MODEL_TYPE = 'mlp' # 'mlp' 或 'lr'(模型类型)
HIDDEN_SIZE = 64 # MLP隐藏层大小LR忽略
NUM_CLASSES = 2 # 类别数(正面/负面二分类)
KEEP_PROB = 1.0 # Dropout保留概率LR忽略设为1即可
# ==================== 训练相关 ====================
LEARNING_RATE = 0.06 # 学习率
NUM_EPOCHS = 101 # 训练轮数
BATCH_SIZE = 65 # 批次大小
# ==================== 类别权重(解决数据不平衡问题)====================
USE_CLASS_WEIGHT = True # True=启用类别权重, False=不启用(对比用)
# 权重计算公式: n_samples / (n_classes * n_class_i)
# 正面评论多所以权重小,负面评论少所以权重大
CLASS_WEIGHT_POS = 0.85 # 正面类权重(自动计算
CLASS_WEIGHT_NEG = 1.75 # 负面类权重(自动计算
# ==================== 实验相关 ====================
RUN_COMPARISON = False # True=运行对比实验, False=运行单个模型
COMPARE_MODELS = ['lr', 'mlp'] # 要对比的模型列表
COMPARE_VECTORS = ['bow', 'tfidf'] # 要对比的向量化方式
# ==================== 其他 ====================
RANDOM_SEED = 42 # 随机种子(保证可复现)
VERBOSE = True # 打印详细日志
# -*- coding: utf-8 -*-
"""
手写数字识别 - 超参数配置
纯NumPy实现的两层全连接神经网络
"""
# ===== 数据参数 =====
ONE_HOT = True # 标签是否使用One-Hot编码
# ===== 模型结构 =====
INPUT_SIZE = 784 # 28x28 = 784 像素
HIDDEN_SIZE = 128 # 隐藏层神经元数量
NUM_CLASSES = 10 # 0-9 十个数字
KEEP_PROB = 1.0 # Dropout保留比例1.0=不使用Dropout
# ===== 训练参数 =====
LEARNING_RATE = 0.1 # 学习率
NUM_EPOCHS = 50 # 训练轮数
BATCH_SIZE = 64 # 批大小
# ===== 随机种子(保证可复现) =====
SEED = 42
# ===== 实验配置 =====
RUN_COMPARISON = False # 是否运行对比实验
# ===== 依赖说明 =====
# 本项目需要以下库:
# numpy - 数值计算
# scikit-learn - 加载MNIST数据集会自动下载
# pandas - sklearn的依赖
#
# 安装命令:
# pip install numpy scikit-learn pandas
#
# 数据说明:
# 首次运行时会自动从OpenML下载MNIST数据集约12MB
# 下载后会自动缓存,后续运行直接使用缓存数据

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# -*- coding: utf-8 -*-
"""
数据加载与向量化模块
支持两种向量化方法:
1. BoW (Bag of Words) - 词频向量
2. TF-IDF - 词频-逆文档频率向量
TF-IDF 的优势:
- 降低常见词(如"""")的权重
- 提升罕见词的信息量
- 通常效果优于简单BoW
"""
import os
import re
import csv
import math
import jieba
import numpy as np
from collections import Counter
try:
import urllib.request
import ssl
DOWNLOAD_AVAILABLE = True
except ImportError:
DOWNLOAD_AVAILABLE = False
DATASET_URL = "https://raw.githubusercontent.com/SophonPlus/ChineseNlpCorpus/master/datasets/ChnSentiCorp_htl_all/ChnSentiCorp_htl_all.csv"
def download_dataset(data_dir):
"""下载数据集(如果不存在)"""
csv_path = os.path.join(data_dir, 'ChnSentiCorp_htl_all.csv')
if os.path.exists(csv_path):
print(f"数据已存在: {csv_path}")
return True
if not DOWNLOAD_AVAILABLE:
return False
print("正在下载数据集...")
ssl_context = ssl.create_default_context()
ssl_context.check_hostname = False
ssl_context.verify_mode = ssl.CERT_NONE
try:
request = urllib.request.Request(DATASET_URL, headers={'User-Agent': 'Mozilla/5.0'})
response = urllib.request.urlopen(request, timeout=120, context=ssl_context)
os.makedirs(data_dir, exist_ok=True)
with open(csv_path, 'wb') as f:
f.write(response.read())
print(f"下载完成: {csv_path}")
return True
except Exception as e:
print(f"下载失败: {e}")
return False
def load_raw_data(data_dir):
"""加载原始数据"""
csv_path = os.path.join(data_dir, 'ChnSentiCorp_htl_all.csv')
texts, labels = [], []
with open(csv_path, 'r', encoding='utf-8') as f:
reader = csv.reader(f)
for row in reader:
if len(row) < 2:
continue
try:
label = int(row[0])
review = row[1].strip()
if review:
texts.append(review)
labels.append(label)
except (ValueError, IndexError):
continue
return texts, np.array(labels)
def tokenize(text):
"""中文分词"""
text = re.sub(r'[^\u4e00-\u9fa5a-zA-Z]', ' ', text)
words = jieba.lcut(text)
return [w for w in words if len(w) > 1]
# ==================== 向量化器 ====================
class BaseVectorizer:
"""向量化器基类"""
def fit(self, texts): pass
def transform(self, texts): pass
def fit_transform(self, texts): pass
class BoWVectorizer(BaseVectorizer):
"""
词袋模型 (Bag of Words)
原理:统计每个词在文本中出现的次数
向量维度 = 词表大小
每个维度 = 该词在本文本中出现的次数
"""
def __init__(self, max_features, max_seq_len):
self.max_features = max_features
self.max_seq_len = max_seq_len
self.vocab = {}
self.doc_freq = {} # 文档频率
self.num_docs = 0
def fit(self, texts):
"""构建词表(基于词频)"""
counter = Counter()
doc_counter = Counter() # 统计包含该词的文档数
for text in texts:
words = tokenize(text)
unique_words = set(words)
counter.update(words)
for w in unique_words:
doc_counter[w] += 1
self.num_docs = len(texts)
# 取最高频的词
most_common = counter.most_common(self.max_features)
self.vocab = {word: idx for idx, (word, _) in enumerate(most_common)}
# 记录文档频率用于TF-IDF
self.doc_freq = {w: doc_counter[w] for w in self.vocab}
print(f" BoW词表大小: {len(self.vocab)}")
return self
def transform(self, texts):
"""将文本转换为词频向量"""
vectors = []
for text in texts:
words = tokenize(text)
freq = [0] * self.max_seq_len
for i, word in enumerate(words[:self.max_seq_len]):
if word in self.vocab:
freq[i] = 1 # 二值(出现=1不出现=0
vectors.append(freq)
return np.array(vectors, dtype=np.float32)
def fit_transform(self, texts):
self.fit(texts)
return self.transform(texts)
class TFIDFVectorizer(BaseVectorizer):
"""
TF-IDF 向量器
原理:
- TF(词频) = 词在本文本中出现的次数
- IDF(逆文档频率) = log(总文档数 / 包含该词的文档数)
- TF-IDF = TF × IDF
优势:
- 降低常见无意义词的权重(如""""
- 提升罕见但有信息量的词
"""
def __init__(self, max_features, max_seq_len):
self.max_features = max_features
self.max_seq_len = max_seq_len
self.vocab = {}
self.idf = {} # 存储每个词的IDF值
self.num_docs = 0
def fit(self, texts):
"""构建词表并计算IDF"""
counter = Counter()
doc_counter = Counter()
for text in texts:
words = tokenize(text)
unique_words = set(words)
counter.update(words)
for w in unique_words:
doc_counter[w] += 1
self.num_docs = len(texts)
# 计算每个词的IDF
# IDF = log(总文档数 / 包含该词的文档数)
idf_values = {}
for word, df in doc_counter.items():
idf_values[word] = math.log(self.num_docs / (df + 1)) + 1 # 加1防零
# 取IDF值最高的词信息量最大的词
sorted_words = sorted(idf_values.items(), key=lambda x: x[1], reverse=True)
self.vocab = {word: idx for idx, (word, _) in enumerate(sorted_words[:self.max_features])}
# 保存IDF值
self.idf = {word: idf_values[word] for word in self.vocab}
print(f" TF-IDF词表大小: {len(self.vocab)}")
print(f" 平均IDF: {np.mean(list(self.idf.values())):.3f}")
return self
def transform(self, texts):
"""将文本转换为TF-IDF向量"""
vectors = []
for text in texts:
words = tokenize(text)
# 计算TF
tf = Counter(words)
tf_sum = len(words) if words else 1
# 生成向量
vec = [0.0] * self.max_seq_len
for i, word in enumerate(words[:self.max_seq_len]):
if word in self.vocab:
# TF × IDF
vec[i] = (tf[word] / tf_sum) * self.idf.get(word, 0)
vectors.append(vec)
return np.array(vectors, dtype=np.float32)
def fit_transform(self, texts):
self.fit(texts)
return self.transform(texts)
def load_data(data_dir, max_features, max_seq_len, vectorizer_type='tfidf'):
"""
加载并向量化数据
参数:
- vectorizer_type: 'tfidf''bow'
"""
if not download_dataset(data_dir):
raise RuntimeError("数据加载失败,请检查网络或手动下载数据集")
print("正在加载数据...")
texts, labels = load_raw_data(data_dir)
print(f"总评论数: {len(texts)}, 正面: {sum(labels)}, 负面: {len(labels) - sum(labels)}")
# 选择向量化器
if vectorizer_type == 'tfidf':
vectorizer = TFIDFVectorizer(max_features, max_seq_len)
vec_name = "TF-IDF"
else:
vectorizer = BoWVectorizer(max_features, max_seq_len)
vec_name = "BoW"
print(f"正在使用{vec_name}向量化...")
X = vectorizer.fit_transform(texts)
y = labels
# 打乱并划分
np.random.seed(42)
indices = np.random.permutation(len(X))
X = X[indices]
y = y[indices]
split_idx = int(len(X) * 0.8)
X_train, X_test = X[:split_idx], X[split_idx:]
y_train, y_test = y[:split_idx], y[split_idx:]
print(f"训练集: {len(X_train)}条, 测试集: {len(X_test)}")
return X_train, y_train, X_test, y_test, vectorizer
if __name__ == '__main__':
# 测试
print("=" * 60)
print("测试 TF-IDF 向量化")
print("=" * 60)
X_train, y_train, X_test, y_test, vec = load_data(
'data/ChnSentiCorp', max_features=3000, max_seq_len=100,
vectorizer_type='tfidf'
)
print(f"\nX_train shape: {X_train.shape}")
print(f"X_train sample (前5个特征): {X_train[0][:5]}")
# -*- coding: utf-8 -*-
"""
数据集模块 - MNIST手写数字数据集加载
优先从本地data/目录加载如果文件不存在则从sklearn下载
支持两种格式:.gz官方格式和 .zip某些下载源
"""
import os
import struct
import gzip
import zipfile
import numpy as np
from config import *
def local_files_exist():
"""检查本地数据文件是否存在且完整"""
data_dir = os.path.join(os.path.dirname(__file__), 'data')
# 支持 .gz 和 .zip 格式MNIST官方用.gz但有些下载是zip
files = {
'train-images-idx3-ubyte': {'gz': 9912422, 'zip': 9187390},
'train-labels-idx1-ubyte': {'gz': 28881, 'zip': 28405},
't10k-images-idx3-ubyte': {'gz': 1648877, 'zip': 1534055},
't10k-labels-idx1-ubyte': {'gz': 5148, 'zip': 4563},
}
found_files = {}
missing = []
for base_name, sizes in files.items():
gz_path = os.path.join(data_dir, base_name + '.gz')
zip_path = os.path.join(data_dir, base_name + '.zip')
if os.path.exists(gz_path):
found_files[base_name] = (gz_path, sizes['gz'], 'gz')
elif os.path.exists(zip_path):
found_files[base_name] = (zip_path, sizes['zip'], 'zip')
else:
missing.append(base_name)
if missing:
return False, f"文件不存在: {', '.join(missing)}"
# 检查大小是否正确
for base_name, (filepath, expected_size, fmt) in found_files.items():
actual_size = os.path.getsize(filepath)
if actual_size != expected_size:
return False, f"文件大小错误: {base_name} (期望{expected_size}, 实际{actual_size})"
return True, "所有文件完整"
def parse_idx_images(filepath):
"""解析IDX格式图像支持.gz和.zip"""
if filepath.endswith('.zip'):
with zipfile.ZipFile(filepath, 'r') as zf:
# zip内的文件名没有.gz后缀
inner_name = zf.namelist()[0]
with zf.open(inner_name) as f:
magic, num, rows, cols = struct.unpack('>IIII', f.read(16))
images = np.frombuffer(f.read(), dtype=np.uint8)
images = images.reshape(num, rows * cols)
return images
else:
with gzip.open(filepath, 'rb') as f:
magic, num, rows, cols = struct.unpack('>IIII', f.read(16))
images = np.frombuffer(f.read(), dtype=np.uint8)
images = images.reshape(num, rows * cols)
return images
def parse_idx_labels(filepath):
"""解析IDX格式标签支持.gz和.zip"""
if filepath.endswith('.zip'):
with zipfile.ZipFile(filepath, 'r') as zf:
# zip内的文件名没有.gz后缀
inner_name = zf.namelist()[0]
with zf.open(inner_name) as f:
magic, num = struct.unpack('>II', f.read(8))
labels = np.frombuffer(f.read(), dtype=np.uint8)
return labels
else:
with gzip.open(filepath, 'rb') as f:
magic, num = struct.unpack('>II', f.read(8))
labels = np.frombuffer(f.read(), dtype=np.uint8)
return labels
def load_data_from_local():
"""从本地文件加载MNIST自动检测.gz或.zip格式"""
data_dir = os.path.join(os.path.dirname(__file__), 'data')
def find_file(base_name):
"""自动找文件,支持.gz和.zip"""
gz_path = os.path.join(data_dir, base_name + '.gz')
zip_path = os.path.join(data_dir, base_name + '.zip')
if os.path.exists(gz_path):
return gz_path
elif os.path.exists(zip_path):
return zip_path
else:
raise FileNotFoundError(f"找不到 {base_name} 的 .gz 或 .zip 文件")
X_train = parse_idx_images(find_file('train-images-idx3-ubyte'))
y_train = parse_idx_labels(find_file('train-labels-idx1-ubyte'))
X_test = parse_idx_images(find_file('t10k-images-idx3-ubyte'))
y_test = parse_idx_labels(find_file('t10k-labels-idx1-ubyte'))
return X_train, y_train, X_test, y_test
def load_data_from_sklearn():
"""从sklearn加载MNIST备选方案"""
from sklearn.datasets import fetch_openml
print(" 正在从OpenML下载数据首次可能需要1-2分钟...")
mnist = fetch_openml('mnist_784', version=1, as_frame=False, parser='auto')
X = mnist.data.astype(np.float32)
y = mnist.target.astype(int)
X_train = X[:60000] / 255.0
X_test = X[60000:] / 255.0
y_train = y[:60000]
y_test = y[60000:]
return X_train, y_train, X_test, y_test
def one_hot_encode(y, num_classes=10):
one_hot = np.zeros((len(y), num_classes))
one_hot[np.arange(len(y)), y] = 1
return one_hot
def load_data():
"""
加载MNIST数据集
优先从本地data/目录加载如果文件不完整则从sklearn下载
"""
print("\n" + "=" * 50)
print("MNIST 数据集加载")
print("=" * 50)
# 优先检查本地文件
exists, msg = local_files_exist()
if exists:
print(f"\n ✓ 发现本地数据文件: {msg}")
X_train, y_train, X_test, y_test = load_data_from_local()
else:
print(f"\n 本地文件: {msg}")
print(" 尝试从sklearn下载...")
try:
X_train, y_train, X_test, y_test = load_data_from_sklearn()
except Exception as e:
print(f"\n 下载失败: {e}")
print("\n 请确保 data/ 目录下有完整的4个数据文件")
raise
# 归一化和One-Hot
X_train = X_train.astype(np.float32) / 255.0
X_test = X_test.astype(np.float32) / 255.0
y_train = one_hot_encode(y_train, NUM_CLASSES)
y_test = one_hot_encode(y_test, NUM_CLASSES)
print(f"\n ✓ 完成!")
print(f" 训练集: {X_train.shape[0]} 样本")
print(f" 测试集: {X_test.shape[0]} 样本")
print(f" 数值范围: [{X_train.min():.2f}, {X_train.max():.2f}]")
return X_train, y_train, X_test, y_test
if __name__ == '__main__':
X_train, y_train, X_test, y_test = load_data()
print(f"\n训练数据: {X_train.shape}")

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# -*- coding: utf-8 -*-
"""
主程序入口
使用方式:
1. 运行单个模型(默认):
python main.py
修改 config.py 中的 MODEL_TYPE 和 VECTORIZER_TYPE 来切换配置
2. 运行对比实验:
修改 config.py 中 RUN_COMPARISON = True
这会依次运行:
- 实验1: BoW vs TF-IDF (固定LR模型)
- 实验2: LR vs MLP (固定TF-IDF)
- 实验3: 不同学习率对比
- 实验4: 不同隐藏层大小对比
最后输出汇总报告
"""
from train import main
if __name__ == '__main__':
print("\n" + "=" * 70)
print("文本分类实验 - 纯NumPy实现")
print("数据集: ChnSentiCorp (中文酒店评论)")
print("模型: Logistic Regression / MLP")
print("向量化: BoW / TF-IDF")
print("=" * 70 + "\n")
main()
# -*- coding: utf-8 -*-
"""
主程序 - 手写数字识别 MLP 纯NumPy实现
使用方法:
python main.py # 运行默认配置
python main.py --compare # 运行对比实验
依赖:
pip install numpy requests
"""
import numpy as np
import time
from datetime import datetime
from model_numpy import MLP
from dataset import load_data
from config import *
def train_and_evaluate():
"""
训练并评估模型
"""
print("=" * 60)
print("手写数字识别 - 纯NumPy MLP实现")
print("=" * 60)
# ===== 加载数据 =====
try:
X_train, y_train, X_test, y_test = load_data()
except Exception as e:
print(f"\n错误: {e}")
print("\n请手动下载数据文件:")
print(" 1. 创建 data/ 目录")
print(" 2. 下载以下文件到 data/:")
print(" - train-images-idx3-ubyte.gz (9.9 MB)")
print(" - train-labels-idx1-ubyte.gz (28 KB)")
print(" - t10k-images-idx3-ubyte.gz (1.6 MB)")
print(" - t10k-labels-idx1-ubyte.gz (5 KB)")
print(" 下载地址: https://storage.googleapis.com/tensorflow/tf-keras-datasets/")
return None, None, None
# ===== 创建模型 =====
print("\n[2] 创建MLP模型...")
model = MLP(
input_size=INPUT_SIZE,
hidden_size=HIDDEN_SIZE,
num_classes=NUM_CLASSES,
learning_rate=LEARNING_RATE,
seed=SEED
)
# ===== 训练模型 =====
print("\n[3] 开始训练...")
start_time = time.time()
model.fit(
X_train, y_train,
X_val=X_test, y_val=y_test,
epochs=NUM_EPOCHS,
batch_size=BATCH_SIZE,
verbose=True
)
train_time = time.time() - start_time
# ===== 最终评估 =====
print("\n" + "=" * 60)
print("训练完成!")
print("=" * 60)
train_acc = model.accuracy(X_train, y_train)
test_acc = model.accuracy(X_test, y_test)
print(f"\n最终结果:")
print(f" 训练准确率: {train_acc:.4f} ({train_acc*100:.2f}%)")
print(f" 测试准确率: {test_acc:.4f} ({test_acc*100:.2f}%)")
print(f" 训练时间: {train_time:.2f}")
# ===== 保存模型 =====
timestamp = datetime.now().strftime("%m%d_%H%M%S")
model_path = f"mnist_mlp_{timestamp}"
model.save(model_path)
# ===== 预测示例 =====
print("\n[4] 预测示例:")
indices = np.random.choice(len(X_test), 5, replace=False)
for i, idx in enumerate(indices):
img = X_test[idx]
true_label = np.argmax(y_test[idx])
pred_label = model.predict(img.reshape(1, -1))[0]
prob = model.predict_proba(img.reshape(1, -1))[0]
status = '' if true_label == pred_label else ''
print(f" 样本{i+1}: 真实={true_label}, 预测={pred_label}, "
f"置信度={prob[pred_label]:.2f} {status}")
return model, train_acc, test_acc
def run_comparison():
"""
运行对比实验
"""
print("\n" + "=" * 60)
print("超参数对比实验")
print("=" * 60)
# 加载数据
try:
X_train, y_train, X_test, y_test = load_data()
except Exception as e:
print(f"加载数据失败: {e}")
return
# 实验配置
experiments = [
{"hidden_size": 32, "lr": 0.1, "name": "小模型(32神经元)"},
{"hidden_size": 128, "lr": 0.1, "name": "标准(128神经元)"},
{"hidden_size": 256, "lr": 0.1, "name": "大模型(256神经元)"},
{"hidden_size": 128, "lr": 0.01, "name": "小学习率(0.01)"},
{"hidden_size": 128, "lr": 0.5, "name": "大学习率(0.5)"},
]
results = []
for exp in experiments:
print(f"\n实验: {exp['name']}")
print("-" * 40)
model = MLP(
input_size=INPUT_SIZE,
hidden_size=exp['hidden_size'],
num_classes=NUM_CLASSES,
learning_rate=exp['lr'],
seed=SEED
)
start_time = time.time()
model.fit(X_train, y_train, epochs=30, batch_size=BATCH_SIZE, verbose=False)
train_time = time.time() - start_time
train_acc = model.accuracy(X_train, y_train)
test_acc = model.accuracy(X_test, y_test)
results.append({
'name': exp['name'],
'hidden_size': exp['hidden_size'],
'lr': exp['lr'],
'train_acc': train_acc,
'test_acc': test_acc,
'train_time': train_time
})
print(f" 训练准确率: {train_acc:.4f} | 测试准确率: {test_acc:.4f} | 时间: {train_time:.1f}s")
# 汇总
print("\n" + "=" * 60)
print("实验结果汇总")
print("=" * 60)
print(f"\n{'配置':<25} {'训练准确率':<12} {'测试准确率':<12} {'时间':<8}")
print("-" * 60)
for r in results:
print(f"{r['name']:<25} {r['train_acc']:<12.4f} {r['test_acc']:<12.4f} {r['train_time']:<8.1f}s")
best = max(results, key=lambda x: x['test_acc'])
print(f"\n最佳配置: {best['name']}, 测试准确率: {best['test_acc']:.4f}")
def main():
"""主函数"""
if RUN_COMPARISON:
run_comparison()
else:
train_and_evaluate()
print("\n" + "=" * 60)
print("程序结束!")
print("=" * 60)
if __name__ == '__main__':
import sys
if '--compare' in sys.argv:
RUN_COMPARISON = True
main()

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