Load and save configs

Use OmegaConf.create() for a YAML string and OmegaConf.load() for a YAML file. Both return an OmegaConf config:

>>> from omegaconf import OmegaConf
>>> cfg = OmegaConf.create("""
... server:
...   port: 80
... """)
>>> cfg.server.port
80

Save and load YAML

OmegaConf.save(cfg, path) writes YAML, and OmegaConf.load(path) reads it back. Paths, filenames, and file objects are accepted. YAML preserves values but not the Python schema of a structured config. Use OmegaConf.to_yaml(cfg) when you need a YAML string or OmegaConf.to_container(cfg) when another Python API needs ordinary dictionaries and lists.

>>> yaml_text = OmegaConf.to_yaml(cfg)
>>> print(yaml_text, end="")
server:
  port: 80

to_yaml() accepts PyYAML's default_flow_style option for controlling compact sequence formatting.

>>> matrix = OmegaConf.create({"rows": [[1, 0], [0, 1]]})
>>> print(OmegaConf.to_yaml(matrix, default_flow_style=None), end="")
rows:
- [1, 0]
- [0, 1]

The same operations accept file objects. Loading YAML does not restore a structured config's dataclass or attrs type:

>>> import io
>>> buffer = io.StringIO()
>>> OmegaConf.save(config=cfg, f=buffer)
>>> restored = OmegaConf.load(io.StringIO(buffer.getvalue()))
>>> restored == cfg
True

Pickle

For a Python-only round trip that retains OmegaConf type information, use pickle with trusted data. The resulting file is not guaranteed to work across OmegaConf versions:

>>> import pickle
>>> restored = pickle.loads(pickle.dumps(cfg))
>>> restored == cfg
True