zarr-cm

Python types and utilities for Zarr Conventions Metadata.

Installation

pip install zarr-cm

Supported conventions

Convention	Module	Description
geo-proj	zarr_cm.geo_proj	Coordinate reference system information
spatial	zarr_cm.spatial	Spatial coordinate metadata
multiscales	zarr_cm.multiscales	Multiscale pyramid layout
license	zarr_cm.license	License specifiers
uom	zarr_cm.uom	Units of measurement

Usage

Each convention module provides the following operations:

• create creates convention metadata.
• validate checks convention metadata for validity.
• insert adds convention metadata to a Zarr attributes dict and returns a new dict with a zarr_conventions entry.
• extract removes convention metadata from an attributes dict and returns the remaining attributes and the extracted convention data.

from zarr_cm import geo_proj

# Create
data = geo_proj.create(code="EPSG:4326")
print(data)
#> {'proj:code': 'EPSG:4326'}

# Validate
print(geo_proj.validate({"proj:code": "EPSG:4326"}))
#> {'proj:code': 'EPSG:4326'}

# Insert
attrs = {"foo": "bar"}
result = geo_proj.insert(attrs, data)
print(result)
"""
{
    'foo': 'bar',
    'proj:code': 'EPSG:4326',
    'zarr_conventions': [
        {
            'uuid': 'f17cb550-5864-4468-aeb7-f3180cfb622f',
            'schema_url': 'https://raw.githubusercontent.com/zarr-experimental/geo-proj/refs/tags/v1/schema.json',
            'spec_url': 'https://github.com/zarr-experimental/geo-proj/blob/v1/README.md',
            'name': 'proj:',
            'description': 'Coordinate reference system information for geospatial data',
        }
    ],
}
"""

# Extract
remaining, extracted = geo_proj.extract(result)
print(remaining)
#> {'foo': 'bar'}
print(extracted)
#> {'proj:code': 'EPSG:4326'}

Multiple conventions

create_many, insert_many, extract_many, and validate_many work with several conventions at once, keyed by convention name. extract_all and validate_all are shortcuts that operate on all known conventions.

from zarr_cm import create_many, extract_all

# Create attributes with multiple conventions at once
attrs = create_many(
    {
        "geo-proj": {"proj:code": "EPSG:4326"},
        "spatial": {"spatial:dimensions": ["y", "x"]},
        "license": {"spdx": "MIT"},
    }
)
print(sorted(attrs.keys()))
#> ['license', 'proj:code', 'spatial:dimensions', 'zarr_conventions']

# Extract all known conventions
remaining, extracted = extract_all(attrs)
print(remaining)
#> {}
print(sorted(extracted.keys()))
#> ['geo-proj', 'license', 'spatial']
print(extracted["geo-proj"])
#> {'proj:code': 'EPSG:4326'}