use 'cpu' instead of None for Iterator

[avinashsai]

Fixes #376
Points default device to torch cpu instead of None if no device is specified to be compatible with torch device types

[zhangguanheng66]

It makes sense that the default device is cpu if device is None. But if device is provided in the init func, you still force to use cpu. Seem not correct. And double check the doc explains this clearly.

[avinashsai]

Should I change accordingly or leave it as it is??

[zhangguanheng66]

Should I change accordingly or leave it as it is??

If device is provided in the __init__ func, it should be assigned to device. Otherwise, the device is set to the default, which is cpu

[avinashsai]

I will change accordingly

[avinashsai]

Made changes as per your comments

[zhangguanheng66]

This is not correct. The device is under if isinstance statement. For None device, it's no way to enter it.

[zhangguanheng66]

You have to rebase to the master branch

[avinashsai]

changed as per your comments

[zhangguanheng66]

The CI tests fail.

[avinashsai]

i fixed indentation issue

[zhangguanheng66]

The circleci tests need to pass. Please check the log since the errors are relevant.

[avinashsai]

Fixed

[zhangguanheng66]

nit: could you remove the parentheses in Python conditional?

[avinashsai]

Done!!

[zhangguanheng66]

In the doc, device could also be string. Should we also cover that as:

if device is None:
    device = torch.device('cpu')
elif isinstance(device, str):
    device = torch.device(device)

[avinashsai]

I would also like to add one more thing. How about adding a warning if cuda is available and user still preferred 'cpu'

if torch.cuda.is_available():
    if device is None or device=='cpu':
        logger.warning("you have gpu available but preferred device as cpu")
if device is None:
    device = torch.device('cpu')
elif isinstance(device, str):
    device = torch.device(device)

[cpuhrsch]

I wouldn't assume that GPU is preferred if it is available. This might be used in some unexpected context.

Alongside updating the default behavior we should also update the doc string to document this.

[avinashsai]

Sometimes users forget to pass 'gpu' parameter even if gpu is available. So, if we send a warning, users can rectify it.

[cpuhrsch]

Yes, but it adds verbosity we commonly don't have. I suggest we do this in a separate PR where we address logging issues in general. If we were to do it for this operator we should also do it for the other ones and that'll require some strategy.

[avinashsai]

ok then, for now i will ignore and add only required ones.

[avinashsai]

@zhangguanheng66 please merge this

[cpuhrsch]

@avinashsai - The docstring wasn't updated. Please send a follow-up PR.

[cpuhrsch]

 device (str or `torch.device`): A string or instance of `torch.device`
            specifying which device the Variables are going to be created on.	            specifying which device the Variables are going to be created on.
            If left as default, the tensors will be created on cpu. Default: None.	            If left as default, the tensors will be created on cpu. Default: None.

but it should be Default: cpu or such.

[avinashsai]

@cpuhrsch where should I edit the docs? Iam not able to find the location.

[zhangguanheng66]

The default is None and None will be converted to cpu device.