I thought that I found my answer:
x1_dataset = torch.tensor(D.inputFeature1.values, dtype=torch.float)

x2_dataset = torch.tensor(D.inputFeature2.values, dtype=torch.float)

x3_dataset = torch.tensor(D.inputFeature3.values, dtype=torch.float)

x_dataset = [x1_dataset, x2_dataset, x3_dataset]

However, in this way x_dataset is of type list while I would like to have a type tensor
Could you help me?