Variable interpolation, get the name of a group instead of the configuration provided by that group.

[YerePhy]

Hi,

When I try to do varaible interpolation:

defaults:
  - datamodule: monai_holdout
  - lightningmodule: unet_like
  - trainer: standard
  - _self_
datamodule_type: "${datamodule}"

Being my main script:

import hydra
from omegaconf import DictConfig, OmegaConf
from utils import datamodule_factory, lightningmodule_factory


@hydra.main(config_path="./configs/train", config_name="config")
def main(cfg: DictConfig):
    """
    Perform training.
    """
    OmegaConf.register_new_resolver("get_method", hydra.utils.get_method)
    cfg = hydra.utils.instantiate(cfg, _recursive_=True)
    
    print(cfg['datamodule_type'])
main()

I would like to have in cfg["datamodule_type"] the name of the group provided to datamodule in the defaults list i.e. "monai_holdout". However, I am getting the configuration provided by that group:

Output main script:
{'dataset_path': '/home/yere/Repositories/brain_tumor/datasets/dataset_concat', 'modalities': , 'ext': '.nii.gz', 'batch_size': 5, 'num_workers': 1, 'load_subset': 0.01, 'splitter': functools.partial(, ratios=[0.7, 0.15, 0.15], num_partitions=3), 'patch_func': , 'train_stage_transformations': , 'test_stage_transformations': }

Is it possible to have only the name of the group by variable interpolation or by other method?

[Jasha10]

I believe this is currently not possible. Once Hydra composes the config object, the defaults lists are erased and the information about "where a given subconfig came from" is gone.
One idea I have seen before is to add name: monai_holdout to your monai_holdout.yaml file.

[YerePhy]

Okay, thanks for pointing that out @Jasha10, I was doing something similar but now I've changed to this approach.