pytorchloss-functionimbalanced-datalstm-stateful

Using LSTM stateful for passing context b/w batches; may be some error in context passing, not getting good results?


I have checked the data before giving it to the network. The data is correct.

Using LSTM and passing the context b/w batches. per_class_accuracy is changing, but the loss is not going down. Been stuck for long, not sure if there is an error in the Code?

I have multi-class classification problem based upon an imbalanced dataset

Dataset_type: CSV

Dataset_size: 20000

Based upon CSV data of sensors

X = 0.6986111111111111,0,0,1,0,1,0,0,0,1,0,0,0,0,1,0,0,0,1,1,0,0,0

Y = leaveHouse

Per class accuracy: {'leaveHouse': 0.34932855, 'getDressed': 1.0, 'idle': 0.8074534, 'prepareBreakfast': 0.8, 'goToBed': 0.35583413, 'getDrink': 0.0, 'takeShower': 1.0, 'useToilet': 0.0, 'eatBreakfast': 0.8857143}

Training:

# Using loss weights, the inverse of class frequency

criterion = nn.CrossEntropyLoss(weight = class_weights)

 hn, cn = model.init_hidden(batch_size)
            for i, (input, label) in enumerate(trainLoader):
                hn.detach_()
                cn.detach_()
                input = input.view(-1, seq_dim, input_dim)

                if torch.cuda.is_available():
                    input = input.float().cuda()
                    label = label.cuda()
                else:
                    input = input.float()
                    label = label

                # Forward pass to get output/logits
                output, (hn, cn) = model((input, (hn, cn)))

                # Calculate Loss: softmax --> cross entropy loss
                loss = criterion(output, label)#weig pram
                running_loss += loss
                loss.backward()  # Backward pass
                optimizer.step()  # Now we can do an optimizer step
                optimizer.zero_grad()  # Reset gradients tensors

Network


class LSTMModel(nn.Module):
    def init_hidden(self, batch_size):
        self.batch_size = batch_size
        if torch.cuda.is_available():
            hn = torch.zeros(self.layer_dim, self.batch_size, self.hidden_dim).cuda()
            # Initialize cell state
            cn = torch.zeros(self.layer_dim, self.batch_size, self.hidden_dim).cuda()
        else:
            hn = torch.zeros(self.layer_dim, self.batch_size, self.hidden_dim)
            # Initialize cell state
            cn = torch.zeros(self.layer_dim, self.batch_size, self.hidden_dim)
        return hn, cn

    def __init__(self, input_dim, hidden_dim, layer_dim, output_dim, seq_dim):
        super(LSTMModel, self).__init__()
        # Hidden dimensions
        self.hidden_dim = hidden_dim

        # Number of hidden layers
        self.layer_dim = layer_dim

        self.input_dim = input_dim
        # Building your LSTM
        # batch_first=True causes input/output tensors to be of shape
        # (batch_dim, seq_dim, feature_dim)
        self.lstm = nn.LSTM(self.input_dim, hidden_dim, layer_dim, batch_first=True)

        # Readout layer
        self.fc = nn.Linear(hidden_dim, output_dim)
        self.relu = nn.ReLU()
        self.softmax = nn.Softmax(dim=1)
        self.seq_dim = seq_dim

    def forward(self, inputs):
        # Initialize hidden state with zeros
        input, (hn, cn) = inputs
        input = input.view(-1, self.seq_dim, self.input_dim)

        # time steps
        out, (hn, cn) = self.lstm(input, (hn, cn))

        # Index hidden state of last time step
        out = self.fc(out[:, -1, :])
        out = self.softmax(out)
        return out, (hn,cn)


Solution

  • One problem you might have is CrossEntropyLoss combines a log softmax operation with negative log likelihood loss, but you're applying a softmax in your model. You should pass the raw logits out of the final layer to CrossEntropyLoss.

    Also I an't say without seeing the models forward pass, but it looks like you're applying the softmax on dimension 1 to a tensor that (I'm inferring) has shape batch_size, sequence_length, output_dim, when you should be applying it along the output dim.