add checkpoints

anemoi/utils/checkpoints.py

@@ -0,0 +1,41 @@
+# (C) Copyright 2024 ECMWF.
+#
+# This software is licensed under the terms of the Apache Licence Version 2.0
+# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+# In applying this licence, ECMWF does not waive the privileges and immunities
+# granted to it by virtue of its status as an intergovernmental organisation
+# nor does it submit to any jurisdiction.
+
+import json
+import logging
+import os
+import zipfile
+
+LOG = logging.getLogger(__name__)
+
+DEFAULT_NAME = "anemoi-metadata.json"
+
+
+def load_metadata(path, name=DEFAULT_NAME):
+    with zipfile.ZipFile(path, "r") as f:
+        metadata = None
+        for b in f.namelist():
+            if os.path.basename(b) == name:
+                if metadata is not None:
+                    LOG.warning(f"Found two '{name}' if {path}")
+                metadata = b
+
+    if metadata is not None:
+        with zipfile.ZipFile(path, "r") as f:
+            return json.load(f.open(metadata, "r"))
+    else:
+        raise ValueError(f"Could not find {name} in {path}")
+
+
+def save_metadata(path, metadata, name=DEFAULT_NAME):
+    with zipfile.ZipFile(path, "a") as zipf:
+        base, _ = os.path.splitext(os.path.basename(path))
+        zipf.writestr(
+            f"{base}/{name}",
+            json.dumps(metadata),
+        )