I’m currently switching from tensorflow to pytorch and facing the warning `UserWarning: Using a target size (torch.Size([400])) that is different to the input size (torch.Size([400, 1])). This will likely lead to incorrect results due to broadcasting. Please ensure they have the same size`

I came across that `unsqueeze(1)`

on my target could help to resolve my problem, however, I do so obtain problems in regard of the multitarget which results from the shape my loss function (crossentropy) expects.

Here is a minimal example to my code:

```
import torch
import torch.nn as nn
import torch.optim as optim
from torch.utils.data import Dataset, DataLoader, TensorDataset
import torch.nn.functional as F
X1 = torch.randn(400, 1, 9999)
X2 = torch.randn((400,1, 9999))
aux1 = torch.randn(400,1)
aux2 = torch.randn(400,1)
aux3 = torch.randn(400,1)
y1 = torch.rand(400,)
y2 = torch.rand(400,)
y3 = torch.rand(400,)
import torch
import torch.nn as nn
import torch.optim as optim
from torch.utils.data import Dataset, DataLoader, TensorDataset
import torch.nn.functional as F
# In[18]:
class MultiTaskDataset:
def __init__(self,
amplitude,
phase,
weight,
temperature,
humidity,
shelf_life_clf,
shelf_life_pred,
thickness_pred
):
self.amplitude = amplitude
self.phase = phase
self.weight = weight
self.temperature = temperature
self.humidity = humidity
self.shelf_life_clf = shelf_life_clf
self.shelf_life_pred = shelf_life_pred
self.thickness_pred = thickness_pred
def __len__(self):
return self.amplitude.shape[0]
def __getitem__(self, idx):
#inputs
amplitude = self.amplitude[idx]
phase = self.phase[idx]
weight = self.weight[idx]
temperature = self.temperature[idx]
humidity = self.humidity[idx]
#outputs
shelf_life_clf = self.shelf_life_clf[idx]
shelf_life_reg = self.shelf_life_pred[idx]
thickness_pred = self.thickness_pred[idx]
return ([torch.tensor(amplitude, dtype=torch.float32),
torch.tensor(phase, dtype=torch.float32),
torch.tensor(weight, dtype=torch.float32),
torch.tensor(temperature, dtype=torch.float32),
torch.tensor(humidity, dtype=torch.float32)],
[torch.tensor(shelf_life_clf, dtype=torch.long),
torch.tensor(shelf_life_reg, dtype=torch.float32),
torch.tensor(thickness_pred, dtype=torch.float32)])
# In[19]:
# train loader
dataset = MultiTaskDataset(X1, X2, aux1, aux2, aux3,
y1,y2,y3)
train_loader = DataLoader(dataset, batch_size=512, shuffle=True, num_workers=0)
# test loader
# In[20]:
class MyModel(nn.Module):
def __init__(self):
super(MyModel, self).__init__()
self.features_amp = nn.Sequential(
nn.LazyConv1d(1, 3, 1),
)
self.features_phase = nn.Sequential(
nn.LazyConv1d(1, 3, 1),
)
self.backbone1 = nn.Sequential(
nn.LazyConv1d(64,3,1),
nn.LazyConv1d(64,3,1),
nn.AvgPool1d(3),
nn.Dropout(0.25),
)
self.backbone2 = nn.Sequential(
nn.Conv1d(64, 32,3,1),
nn.Conv1d(32, 32,3,1),
nn.AvgPool1d(3),
nn.Dropout(0.25),
)
self.backbone3 = nn.Sequential(
nn.Conv1d(32, 16,3,1),
nn.Conv1d(16, 16,3,1),
nn.AvgPool1d(3),
nn.Dropout(0.25),
)
self.classifier = nn.LazyLinear(2)
self.shelf_life_reg = nn.LazyLinear(1)
self.thickness_reg = nn.LazyLinear(1)
def forward(self, x1, x2, aux1, aux2, aux3):
x1 = self.features_amp(x1)
x2 = self.features_phase(x2)
x1 = x1.view(x1.size(0),-1)
x2 = x2.view(x2.size(0),-1)
x = torch.cat((x1, x2), dim=-1)
print(x.size())
x = x.unsqueeze(1)
print(x.size())
x = self.backbone1(x)
print(x.size())
x = torch.flatten(x, start_dim=1, end_dim=-1)
x = torch.cat([x, aux1, aux2, aux3], dim=-1)
shelf_life_clf = self.classifier(x)
shelf_life_reg = self.shelf_life_reg(x)
thickness_reg = self.thickness_reg(x)
return (shelf_life_clf,
shelf_life_reg,
thickness_reg)
model = MyModel()
optimizer = optim.Adam(model.parameters(), lr=0.003)
criterion1 = nn.CrossEntropyLoss()
criterion2 = nn.MSELoss()
criterion3 = nn.MSELoss()
# In[21]:
def train(epoch):
model.train()
#exp_lr_scheduler.step()
arr_loss = []
#first_batch = next(iter(train_loader))
for batch_idx, (data, target) in enumerate(train_loader):
#amp, phase = data
clf, reg1, reg2 = target
#print(amp.shape, phase.shape)
#print(target[2].shape)
if torch.cuda.is_available():
device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")
data = [data[i].cuda() for i in range(len(data))]
target = [target[i].cuda() for i in range(len(target))]
model.to(device)
optimizer.zero_grad()
output1, output2, output3 = model(*data)
#losses
loss = criterion1(output1, target[0].long())
loss1 = criterion2(output2, target[1].float())
loss2 = criterion3(output3, target[2].float())
loss = loss + loss1 + loss2
#metrices
loss.backward()
optimizer.step()
print('Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f}'.format(
epoch, (batch_idx + 1) * len(data), len(train_loader.dataset),
100. * (batch_idx + 1) / len(train_loader), loss.data))
arr_loss.append(loss.data)
return arr_loss
def averaged_accuracy(outputs, targets):
assert len(outputs) != len(targets), "number of outputs should equal the number of targets"
accuracy = []
for i in range(len(outputs)):
_, predicted = torch.max(output1.data, 1)
total += target[0].size(0)
correct += (predicted == target[0]).sum()
acc = correct / total *100
accuracy.append(acc)
return torch.mean(accuracy)
# In[22]:
optimizer = optim.Adam(model.parameters(), lr=0.00003)
criterion1 = nn.CrossEntropyLoss()
criterion2 = nn.MSELoss()
criterion3 = nn.MSELoss()
n_epochs = 10
for epoch in range(n_epochs):
train(epoch)
```

Can anybody provide guidance to resolve this problem?