def forward(self, x): ''' Given input of size (batch_size x input_dim), compute output of the network ''' return self.net(x).squeeze(1) def cal_loss(self, pred, target): ''' Calculate loss ''' # TODO: you may implement L1/L2 regularization here eps = 1e-6 l2_reg = 0 alpha = 0.0001 #这段代码是l2正则,但是实际操作l2正则效果不好,大家也也可以调,把下面这段代码取消注释就行 # for name, w in self.net.named_parameters(): # if 'weight' in name: # l2_reg += alpha * torch.norm(w, p = 2).to(device) return torch.sqrt(self.criterion(pred, target) + eps) + l2_reg #lr_reg=0, 上面这段代码用的是均方根误差torch.sqrt(),均方根误差和kaggle评测指标一致,而且训练模型也更平稳
时间: 2024-02-14 09:31:55 浏览: 93
这段代码是定义了一个前向传播函数(forward)和计算损失函数(cal_loss)的方法。
在前向传播函数中,输入x经过self.net神经网络的计算得到输出,然后通过squeeze(1)操作将输出的维度从(batch_size, 1)压缩为(batch_size)。
在计算损失函数时,首先定义了一个很小的常数eps(用于数值稳定性),然后初始化L2正则化项l2_reg为0,并设置正则化系数alpha为0.0001。
接下来的注释部分是一个L2正则化的实现,遍历self.net神经网络的参数,如果参数名中包含'weight',则将该参数的L2范数加到l2_reg上。
最后,计算损失函数的值,使用了均方根误差(RMSE)作为主要的损失项。通过调用self.criterion计算预测值pred和目标值target之间的均方误差,再加上一个很小的常数eps,然后将L2正则化项l2_reg加到损失函数中。
综上所述,这段代码实现了一个带有L2正则化的损失函数的计算,并且使用均方根误差作为主要的损失项。
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class MLP(nn.Module): def __init__( self, input_size: int, output_size: int, n_hidden: int, classes: int, dropout: float, normalize_before: bool = True ): super(MLP, self).__init__() self.input_size = input_size self.dropout = dropout self.n_hidden = n_hidden self.classes = classes self.output_size = output_size self.normalize_before = normalize_before self.model = nn.Sequential( nn.Linear(self.input_size, n_hidden), nn.Dropout(self.dropout), nn.ReLU(), nn.Linear(n_hidden, self.output_size), nn.Dropout(self.dropout), nn.ReLU(), ) self.after_norm = torch.nn.LayerNorm(self.input_size, eps=1e-5) self.fc = nn.Sequential( nn.Dropout(self.dropout), nn.Linear(self.input_size, self.classes) ) self.output_layer = nn.Linear(self.output_size, self.classes) def forward(self, x): self.device = torch.device('cuda') # x = self.model(x) if self.normalize_before: x = self.after_norm(x) batch_size, length, dimensions = x.size(0), x.size(1), x.size(2) output = self.model(x) return output.mean(dim=1) class LabelSmoothingLoss(nn.Module): def __init__(self, size: int, smoothing: float, ): super(LabelSmoothingLoss, self).__init__() self.size = size self.criterion = nn.KLDivLoss(reduction="none") self.confidence = 1.0 - smoothing self.smoothing = smoothing def forward(self, x: torch.Tensor, target: torch.Tensor) -> torch.Tensor: batch_size = x.size(0) if self.smoothing == None: return nn.CrossEntropyLoss()(x, target.view(-1)) true_dist = torch.zeros_like(x) true_dist.fill_(self.smoothing / (self.size - 1)) true_dist.scatter_(1, target.view(-1).unsqueeze(1), self.confidence) kl = self.criterion(torch.log_softmax(x, dim=1), true_dist) return kl.sum() / batch_size
这段代码中定义了一个 MLP 模型以及一个 LabelSmoothingLoss 损失函数。MLP 模型包含了多个线性层和 ReLU 激活函数,以及一个 LayerNorm 层和一个 dropout 层。LabelSmoothingLoss 损失函数主要用于解决分类问题中的过拟合问题,它通过对真实标签进行平滑处理来减少模型对噪声的敏感度。这段代码的 forward 方法实现了 MLP 模型的前向传播,以及 LabelSmoothingLoss 的计算。其中,true_dist 是经过平滑处理后的真实标签分布,kl 是计算 KL 散度的结果,最终返回的是 kl 的平均值。
请在这个DeepCFD的网络添加attention机制,并给出示例代码:import paddle import paddle.nn as nn class Attention(nn.Layer): def __init__(self, input_size, hidden_size): super(Attention, self).__init__() self.input_size = input_size self.hidden_size = hidden_size self.attn = nn.Linear(self.input_size + self.hidden_size, 1) self.softmax = nn.Softmax(axis=1) def forward(self, input, hidden): max_len = input.shape[0] attn_energies = paddle.zeros([max_len, 1]) for i in range(max_len): attn_energies[i] = self.score(input[i], hidden) attn_weights = self.softmax(attn_energies) context = paddle.sum(attn_weights * input, axis=0) return context.unsqueeze(0) def score(self, input, hidden): energy = self.attn(paddle.concat([input, hidden], axis=1)) return energy class DeepCFD(nn.Layer): def __init__(self, input_size, hidden_size, output_size): super(DeepCFD, self).__init__() self.input_size = input_size self.hidden_size = hidden_size self.output_size = output_size self.lstm = nn.LSTM(input_size, hidden_size, num_layers=2, batch_first=True) self.attention = Attention(input_size, hidden_size) self.fc = nn.Linear(hidden_size, output_size) def forward(self, input): output, (hidden, cell) = self.lstm(input) context = self.attention(output, hidden[-1]) output = self.fc(context) return output
好的,下面是添加了Attention机制的DeepCFD网络的示例代码:
import paddle
import paddle.nn as nn
class Attention(nn.Layer):
def __init__(self, input_size, hidden_size):
super(Attention, self).__init__()
self.input_size = input_size
self.hidden_size = hidden_size
self.attn = nn.Linear(self.input_size + self.hidden_size, 1)
self.softmax = nn.Softmax(axis=1)
def forward(self, input, hidden):
max_len = input.shape[1]
attn_energies = paddle.zeros([input.shape[0], max_len, 1])
for i in range(max_len):
attn_energies[:, i] = self.score(input[:, i, :], hidden)
attn_weights = self.softmax(attn_energies)
context = paddle.sum(attn_weights * input, axis=1)
return context
def score(self, input, hidden):
energy = self.attn(paddle.concat([input, hidden], axis=1))
return energy
class DeepCFD(nn.Layer):
def __init__(self, input_size, hidden_size, output_size):
super(DeepCFD, self).__init__()
self.input_size = input_size
self.hidden_size = hidden_size
self.output_size = output_size
self.lstm = nn.LSTM(input_size, hidden_size, num_layers=2, batch_first=True)
self.attention = Attention(input_size, hidden_size)
self.fc = nn.Linear(hidden_size, output_size)
def forward(self, input):
output, (hidden, cell) = self.lstm(input)
context = self.attention(output, hidden[-1])
output = self.fc(context)
return output
在这个示例代码中,我们将Attention机制应用到了LSTM的输出上。在Attention中,我们计算了每个时间步的注意力能量,然后使用softmax函数计算注意力权重。然后,我们将这些权重与LSTM输出相乘并求和,得到上下文向量作为Attention机制的输出。
在DeepCFD中,我们使用了两层LSTM,然后将LSTM输出和最后一个时刻的隐藏状态作为Attention机制的输入。最后,我们将Attention机制的输出传递到一个全连接层中,得到最终的输出。
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