Override value in another file in hydra

Question

I have the following files:

├── callbacks
│   ├── default.yaml
│   ├── early_stopping.yaml
│   └── finetuning.yaml
├── model
│   ├── model_1.yaml
│   └── model_2.yaml
└── train.yaml

train.yaml

defaults:
  - _self_
  - model: model_1
  - callbacks: default

callbacks/default.yaml

defaults:
  - finetuning
  - early_stopping
  - _self_

callbacks/finetuning.yaml

finetuning:
  _target_: callbacks.custom_finetuning.CustomFinetuning
  unfreeze_at_epoch: null
  refreeze_at_epoch: null

model_1.yaml

_target_: models.Model_1

I want override unfreeze_at_epoch and refreeze_at_epoch from model_1.yaml and model_2.yaml so that each model can have different values. I tried adding the following but it does not work:

callbacks:
  finetuning:
    unfreeze_at_epoch: 125
    refreeze_at_epoch: 350

How can I do that?

Answer 1

The config group for model/model_1.yaml is model, meaning that by default all the config values defined there are under the model node. You can change that using the package directive. In this case, by setting package header to _global_.

e.g, model_1.yaml can become:

# @package _global_

model:
  _target_: models.Model_1
callbacks:
  finetuning:
    unfreeze_at_epoch: 125
    refreeze_at_epoch: 350

A few other things to note is that you config composition order, controlled by the _self_ keyword in the defaults list is correct. You can learn more about it here.

Finally, you may want to use the pattern of configuring experiments.