expected scalar type Long but found Float

This error message occurs when there is a type mismatch between the expected data type and the actual data type in a PyTorch tensor.

In this case, the code is expecting a Long data type but found a Float data type. To fix this error, you need to convert the Float tensor to a Long tensor using the `long()` method.

For example:

import torch

# create a Float tensor
float_tensor = torch.tensor([1.0, 2.0, 3.0])

# convert the Float tensor to a Long tensor
long_tensor = float_tensor.long()

# print the Long tensor
print(long_tensor)

Output:

tensor([ 1,  2,  3])

Alternatively, you can also specify the data type when creating the tensor:

import torch

# create a Long tensor
long_tensor = torch.tensor([1, 2, 3], dtype=torch.long)

# print the Long tensor
print(long_tensor)

Output:

tensor([ 1,  2,  3])