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由于独特的设计结构 LSTM适合于处理和预测时间序列中间隔和延迟非常长的重要事件。
LSTM是一种含有LSTM区块(blocks)或其他的一种类神经网络,文献或其他资料中LSTM区块可能被描述成智能网络单元,因为它可以记忆不定时间长度的数值,区块中有一个gate能够决定input是否重要到能被记住及能不能被输出output
LSTM有很多个版本,其中一个重要的版本是GRU(Gated Recurrent Unit),根据谷歌的测试表明,LSTM中最重要的是Forget gate,其次是Input gate,最次是Output gate。
介绍完LSTM的基本内容 接下来实战通过LSTM来预测股市收盘价格
先上结果
1:随着训练次数增加损失函数的图像如下 可以看出基本符合肘部方法 但是局部会产生突变
2:预测结果如下 红色的是预测值 蓝色的是真实值 可以看出除了某几个极值点正确率较高
代码如下
import pandas as pdimport numpy as npimport matplotlib.pyplot as pltimport torchimport torch.nn as nnfrom torch.utils.data import DataLoader, Datasetimport osos.environ["KMP_DUPLICATE_LIB_OK"]="TRUE"def read_dataset(dataset_type):assert dataset_type == "train" or dataset_type == "test"df = pd.read_csv(stock_market_price_{}.csv'.format(dataset_type))# 读入股票数据data = np.array(df['close'])# 获取收盘价序列data = data[::-1]# 反转,使数据按照日期先后顺序排列normalize_data = (data - np.mean(data)) / np.std(data)# 标准化normalize_data = normalize_data[:, np.newaxis]# 增加维度X, y = [], []for i in range(len(normalize_data) - time_step):_x = normalize_data[i:i + time_step]_y = normalize_data[i + time_step]X.append(_x.tolist())y.append(_y.tolist())# plt.figure()# plt.plot(data)# plt.show() # 以折线图展示datareturn X, y# 实验参数设置time_step = 7# 用前七天的数据预测第八天hidden_size = 4# 隐藏层维度lstm_layers = 1# 网络层数batch_size = 64# 每一批次训练多少个样例input_size = 1 # 输入层维度output_size = 1# 输出层维度lr = 0.05# 学习率class myDataset(Dataset):def __init__(self, x, y):self.x = xself.y = ydef __getitem__(self, index):return torch.Tensor(self.x[index]), torch.Tensor(self.y[index])def __len__(self):return len(self.x)class LSTM(nn.Module):def __init__(self, input_size, output_size, hidden_size, device):super(LSTM, self).__init__()self.input_size=input_sizeself.output_size=output_sizeself.hidden_size=hidden_sizeself.device=devicedef _one(a,b):return nn.Parameter(torch.FloatTensor(a,b).to(self.device))def _three():return(_one(input_size,hidden_size), _one(hidden_size,hidden_size), nn.Parameter(torch.zeros(hidden_size).to(self.device)))self.W_xi,self.W_hi,self.b_i=_three()self.W_xf, self.W_hf, self.b_f = _three()self.W_xo, self.W_ho, self.b_o = _three()self.W_xc, self.W_hc, self.b_c = _three()self.W_hq=_one(hidden_size,output_size)self.b_q=nn.Parameter(torch.zeros(output_size).to(self.device))self.params=[self.W_xi,self.W_hi,self.b_i,self.W_xf, self.W_hf, self.b_f, self.W_xo, self.W_ho, self.b_o,self.W_xc, self.W_hc, self.b_c, self.W_hq,self.b_q]for param in self.params:if param.dim()==2:nn.init.xavier_normal_(param)def init_lstm_state(self, batch_size):return (torch.zeros((batch_size, self.hidden_size), device=self.device),torch.zeros((batch_size, self.hidden_size), device=self.device))def forward(self, seq):(H,C)=self.init_lstm_state(seq.shape[0])for step in range(seq.shape[1]):X=seq[:,step,:]I=torch.sigmoid((X@self.W_xi)+(H@self.W_hi)+self.b_i)F = torch.sigmoid((X @ self.W_xf) + (H @ self.W_hf) + self.b_f)O = torch.sigmoid((X @ self.W_xo) + (H @ self.W_ho) + self.b_o)C_tilda=torch.tanh(torch.matmul(X.float(),self.W_xc)+torch.matmul(H.float(),self.W_hc)+self.b_c)C=F*C+I*C_tildaH=O*torch.tanh(C)Y=(H@self.W_hq)+self.b_qreturn Y,(H,C)X_train, y_train = read_dataset('train')X_test, y_test = read_dataset('test')train_dataset = myDataset(X_train, y_train)test_dataset = myDataset(X_test, y_test)train_loader = DataLoader(train_dataset, batch_size, shuffle=True)test_loader = DataLoader(test_dataset, 1)# 设定训练轮数num_epochs = 50device = torch.device('cuda') if torch.cuda.is_available() else torch.device('cpu')hist = np.zeros(num_epochs)model = LSTM(input_size, output_size, hidden_size, device)# 定义优化器和损失函数optimiser = torch.optim.Adam(model.parameters(), lr=lr)# 使用Adam优化算法loss_func = torch.nn.MSELoss(reduction='mean')# 使用均方差作为损失函数for epoch in range(num_epochs):epoch_loss = 0for i, data in enumerate(train_loader):X, y = datapred_y, _ = model(X.to(device))loss = loss_func(pred_y, y.to(device))optimiser.zero_grad()loss.backward()optimiser.step()epoch_loss += loss.item()print("Epoch ", epoch, "MSE: ", epoch_loss)hist[epoch] = epoch_lossplt.plot(hist)plt.show()# 测试model.eval()result = []for i, data in enumerate(test_loader):X, y = datapred_y, _ = model(X.to(device))result.append(pred_y.item())plt.plot(range(len(y_test)), y_test, label="true_y", color="blue")plt.plot(range(len(result)), result, label="pred_y", color="red")plt.legend(loc='best')plt.show()