threshold = max(stats.values()) / 10 ^^^^^^^^^^^^^^^^^^^ ValueError: max() arg is an empty sequence

这个错误`ValueError: max() arg is an empty sequence`通常发生在尝试对一个空序列（即长度为零的列表或元组）调用`max()`函数时。在这个例子中，`stats.values()`返回的是一个值的集合，如果这个集合为空，意味着`stats`字典中没有可迭代的值。

`threshold`变量的计算依赖于`stats.values()`的结果除以10得到最大值的十分之一。当你试图获取空序列的最大值时，Python抛出了这个错误。

要修复这个问题，你需要确保`stats.values()`至少包含一个元素。这可以通过检查`stats.values()`是否为空先进行判断：

if stats.values():
    threshold = max(stats.values()) / 10
else:
    # 如果 stats 是空的，你可以选择一个默认值、None 或者抛出异常
    print("stats values are empty, cannot calculate threshold")

如果你希望即使在`stats`为空的情况下也能设置一个默认阈值，可以提供一个备选值：

default_threshold = 0.0 if not stats.values() else max(stats.values()) / 10
threshold = default_threshold

相关问题

编写pytorch代码，定义LSTMAttention模型，定义一个FA_CPSO优化算法，用FA_CPSO算法有优化模型中神经元个数、dropout比率、batch_size、学习率等超参数，将优化好的超参数传递给模型，在特征训练集X_train.csv和标签训练集y_train.csv上训练模型，将最优的参数设置给模型，在特征测试集X_test.csv和标签测试集y_test.csv上测试模型，进一步优化模型，将优化后的参数设置给模型，并输出测试损失，绘制测试集的预测值和实际值，计算测试集的均方根误差，在预测集上进行预测，设定标签数据最大值的85%为警戒线，绘制预测集的实际值到达的时间和预测值到达的时间

好的，我了解了你的要求。首先，需要安装pytorch和pandas库。

以下是代码实现：

import torch
import torch.nn as nn
import pandas as pd
import numpy as np
from scipy.stats import uniform
from sko.PSO import PSO

# 定义LSTMAttention模型
class LSTMAttention(nn.Module):
    def __init__(self, input_size, hidden_size, output_size, num_layers, dropout):
        super(LSTMAttention, self).__init__()

        self.hidden_size = hidden_size
        self.num_layers = num_layers

        self.lstm = nn.LSTM(input_size, hidden_size, num_layers, batch_first=True, bidirectional=True)
        self.dropout = nn.Dropout(dropout)
        self.fc1 = nn.Linear(hidden_size * 2, output_size)
        self.softmax = nn.Softmax(dim=1)

    def forward(self, x):
        h0 = torch.zeros(self.num_layers * 2, x.size(0), self.hidden_size).to(device)
        c0 = torch.zeros(self.num_layers * 2, x.size(0), self.hidden_size).to(device)

        out, _ = self.lstm(x, (h0, c0))
        out = self.dropout(out)
        out = self.fc1(out[:, -1, :])
        out = self.softmax(out)

        return out

# 加载数据
X_train = pd.read_csv('X_train.csv')
y_train = pd.read_csv('y_train.csv')

X_test = pd.read_csv('X_test.csv')
y_test = pd.read_csv('y_test.csv')

# 转换数据格式
X_train = torch.from_numpy(X_train.values).float()
y_train = torch.from_numpy(y_train.values).long().squeeze()

X_test = torch.from_numpy(X_test.values).float()
y_test = torch.from_numpy(y_test.values).long().squeeze()

# 定义超参数空间
dim = 4
lb = [16, 0.1, 64, 0.0001]
ub = [256, 0.5, 256, 0.1]
pso_bound = np.array([lb, ub])

# 定义FA_CPSO优化算法
class FA_CPSO(PSO):
    def __init__(self, func, lb, ub, dimension, size_pop=50, max_iter=300, w=0.8, c1=2, c2=2, c3=2, p=0.5):
        super().__init__(func, lb, ub, dimension, size_pop, max_iter, w, c1, c2, p)
        self.c3 = c3  # FA_CPSO新增参数
        self.S = np.zeros((self.size_pop, self.dimension))  # 储存每个个体的历代最优位置
        self.F = np.zeros(self.size_pop)  # 储存每个个体的当前适应度值
        self.Fbest = np.zeros(self.max_iter + 1)  # 储存每次迭代的最优适应度值
        self.Fbest[0] = self.gbest_y
        self.S = self.X.copy()

    def evolve(self):
        self.F = self.cal_fitness(self.X)
        self.Fbest[self.gbest_iter] = self.gbest_y
        for i in range(self.size_pop):
            if uniform.rvs() < self.p:
                # 个体位置更新
                self.X[i] = self.S[i] + self.c3 * (self.gbest - self.X[i]) + self.c1 * \
                            (self.pbest[i] - self.X[i]) + self.c2 * (self.pbest[np.random.choice(self.neighbor[i])] - self.X[i])
            else:
                # 个体位置更新
                self.X[i] = self.S[i] + self.c1 * (self.pbest[i] - self.X[i]) + self.c2 * (self.pbest[np.random.choice(self.neighbor[i])] - self.X[i])
            # 边界处理
            self.X[i] = np.clip(self.X[i], self.lb, self.ub)
            # 适应度值更新
            self.F[i] = self.func(self.X[i])
            # 个体历代最优位置更新
            if self.F[i] < self.func(self.S[i]):
                self.S[i] = self.X[i]
        # 全局最优位置更新
        self.gbest = self.S[self.F.argmin()]
        self.gbest_y = self.F.min()

# 定义优化目标函数
def objective_function(para):
    hidden_size, dropout, batch_size, learning_rate = para
    model = LSTMAttention(10, hidden_size, 2, 2, dropout).to(device)
    criterion = nn.CrossEntropyLoss()
    optimizer = torch.optim.Adam(model.parameters(), lr=learning_rate)

    train_dataset = torch.utils.data.TensorDataset(X_train, y_train)
    train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=batch_size, shuffle=True)

    for epoch in range(100):
        for i, (inputs, labels) in enumerate(train_loader):
            inputs = inputs.to(device)
            labels = labels.to(device)

            optimizer.zero_grad()

            outputs = model(inputs)
            loss = criterion(outputs, labels)
            loss.backward()

            optimizer.step()

    test_dataset = torch.utils.data.TensorDataset(X_test, y_test)
    test_loader = torch.utils.data.DataLoader(test_dataset, batch_size=len(test_dataset))

    for inputs, labels in test_loader:
        inputs = inputs.to(device)
        labels = labels.to(device)

        outputs = model(inputs)
        pred = torch.argmax(outputs, dim=1)
        test_loss = criterion(outputs, labels)
        rmse = torch.sqrt(torch.mean((pred - labels) ** 2))

    return test_loss.item() + rmse.item()

# 运行FA_CPSO算法进行超参数优化
device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
fa_cpso = FA_CPSO(objective_function, lb, ub, dim, size_pop=50, max_iter=100)
fa_cpso.run()

# 输出最优超参数
best_hidden_size, best_dropout, best_batch_size, best_learning_rate = fa_cpso.gbest

# 使用最优超参数训练模型
model = LSTMAttention(10, best_hidden_size, 2, 2, best_dropout).to(device)
criterion = nn.CrossEntropyLoss()
optimizer = torch.optim.Adam(model.parameters(), lr=best_learning_rate)

train_dataset = torch.utils.data.TensorDataset(X_train, y_train)
train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=best_batch_size, shuffle=True)

for epoch in range(100):
    for i, (inputs, labels) in enumerate(train_loader):
        inputs = inputs.to(device)
        labels = labels.to(device)

        optimizer.zero_grad()

        outputs = model(inputs)
        loss = criterion(outputs, labels)
        loss.backward()

        optimizer.step()

# 在测试集上进行预测
test_dataset = torch.utils.data.TensorDataset(X_test, y_test)
test_loader = torch.utils.data.DataLoader(test_dataset, batch_size=len(test_dataset))

for inputs, labels in test_loader:
    inputs = inputs.to(device)
    labels = labels.to(device)

    outputs = model(inputs)
    pred = torch.argmax(outputs, dim=1)
    test_loss = criterion(outputs, labels)
    test_rmse = torch.sqrt(torch.mean((pred - labels) ** 2))

# 输出测试损失和测试集的均方根误差
print('Test loss: {:.4f}, Test RMSE: {:.4f}'.format(test_loss.item(), test_rmse.item()))

# 绘制测试集的预测值和实际值
import matplotlib.pyplot as plt

plt.plot(pred.cpu().numpy(), label='Predict')
plt.plot(labels.cpu().numpy(), label='Actual')
plt.legend()
plt.show()

# 在预测集上进行预测
X_pred = torch.from_numpy(pd.read_csv('X_pred.csv').values).float().to(device)

outputs = model(X_pred)
pred = torch.argmax(outputs, dim=1)

# 计算预测值到达警戒线的时间和实际值到达警戒线的时间
threshold = y_train.max() * 0.85
pred_time = np.argmax(pred.cpu().numpy() >= threshold)
actual_time = np.argmax(y_test.cpu().numpy() >= threshold)

# 绘制预测集的实际值到达的时间和预测值到达的时间
plt.axvline(x=pred_time, color='r', linestyle='--')
plt.axvline(x=actual_time, color='g', linestyle='--')
plt.plot(pred.cpu().numpy(), label='Predict')
plt.plot(y_test.cpu().numpy(), label='Actual')
plt.legend()
plt.show()

请注意，这只是一个代码示例，可能需要根据数据集的特点进行调整和修改。