Working with attributes

Zarr arrays and groups support custom key/value attributes, which can be useful for storing application-specific metadata. For example:

import zarr
store = zarr.storage.MemoryStore()
root = zarr.create_group(store=store)
root.attrs['foo'] = 'bar'
z = root.create_array(name='zzz', shape=(10000, 10000), dtype='int32')
z.attrs['baz'] = 42
z.attrs['qux'] = [1, 4, 7, 12]
print(sorted(root.attrs))

['foo']

print('foo' in root.attrs)

True

print(root.attrs['foo'])

bar

print(sorted(z.attrs))

['baz', 'qux']

print(z.attrs['baz'])

42

print(z.attrs['qux'])

[1, 4, 7, 12]

Internally Zarr uses JSON to store array attributes, so attribute values must be JSON serializable.