[SOLVED] Overriding Hydra config with experiment

Overriding Hydra config with experiment

I'm working through this Hydra doc example to override the main config with an experiment config. I'm trying to override main with experiment and I'm not sure where I'm going wrong.

The error I get is:

Exception has occurred: ConstructorError
while constructing a mapping
  in "/home/ghb/projects/aisc/embeddings_and_difficulty/configs_hydra/experiment/experiment.yaml", line 2, column 1
found duplicate key main
  in "/home/ghb/projects/aisc/embeddings_and_difficulty/configs_hydra/experiment/experiment.yaml", line 9, column 1
  File "/home/ghb/projects/aisc/embeddings_and_difficulty/runner.py", line 70, in <module>
    main()
yaml.constructor.ConstructorError: while constructing a mapping
  in "/home/ghb/projects/aisc/embeddings_and_difficulty/configs_hydra/experiment/experiment.yaml", line 2, column 1
found duplicate key main
  in "/home/ghb/projects/aisc/embeddings_and_difficulty/configs_hydra/experiment/experiment.yaml", line 9, column 1

Folder structure:

configs
   |--- experiment
    |--- experiment.yaml
   |--- main
    |--- general.yaml
    |--- debug.yaml
   config.yaml

My config.yaml:

defaults:
  - main: general
  - experiment: experiment

My experiment.yaml:

# @package _global_
defaults:
  - override /main: debug

main:
  TRAINING:
    BACKBONE:
      MAX_EPOCH: 20

My general.yaml:

main:
  TRAINING:
    BACKBONE:
      MAX_EPOCH: 200

My debug.yaml:

main:
  TRAINING:
    BACKBONE:
      MAX_EPOCH: 2

Solution

This error normally appears when Hydra loads a YAML file with a duplicate key. I this case configs_hydra/experiment/experiment.yaml. The file content you provided here does not have a duplicate main key, but I suspect your actual file does. If it doesn't, please provide a zip file with a minimal repro.