Made torch device configurable

Made torch device configurable for each device. Provided default implementation so defining the torch device is not mandatory. Defaults to cuda:0 if cuda is available and CPU otherwise.

edml/helpers/config_helpers.py

 from inspect import signature
 
+import torch
 from hydra.utils import get_class, instantiate
 from omegaconf import OmegaConf, DictConfig
+from omegaconf.errors import ConfigAttributeError
 
 from edml.controllers.base_controller import BaseController
 
@@ -117,3 +119,36 @@ def instantiate_controller(cfg: DictConfig) -> BaseController:
     # Instantiate the controller.
     controller: BaseController = instantiate(cfg.controller)(cfg=cfg)
     return controller
+
+
+def get_torch_device_id(cfg: DictConfig) -> str:
+    """
+    Returns the configured torch_device for the current device.
+    Resorts to default if no torch_device is configured.
+
+    Args:
+        cfg (DictConfig): The config loaded from YAML files.
+
+    Returns:
+        The id of the configured torch_device for the current device.
+
+    Raises:
+        StopIteration: If the device with the given ID cannot be found.
+        ConfigAttributeError: If no device id is present in the config.
+    """
+    own_device_id = cfg.own_device_id
+    try:
+        return next(
+            device_cfg.torch_device
+            for device_cfg in cfg.topology.devices
+            if device_cfg.device_id == own_device_id
+        )
+    except ConfigAttributeError:
+        return _default_torch_device()
+
+
+def _default_torch_device():
+    """
+    Returns the default torch devices, depending on whether cuda is available.
+    """
+    return "cuda:0" if torch.cuda.is_available() else "cpu"