zarr-cm

Python types and utilities for Zarr Conventions Metadata.

Overview

zarr-cm provides typed Python support for the published Zarr 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

Each module provides:

• TypedDict types for convention-specific metadata
• create — create convention metadata
• insert — add convention metadata to a Zarr attributes dict
• extract — remove and return convention metadata from an attributes dict
• validate — check runtime invariants the type system cannot express

Installation

pip install zarr-cm

Usage

from zarr_cm import geo_proj

# Create convention metadata
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 into an attributes dict
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 it back out
remaining, extracted = geo_proj.extract(result)
print(remaining)
#> {'foo': 'bar'}
print(extracted)
#> {'proj:code': 'EPSG:4326'}