Annlite

One can use Annlite as the document store for DocumentArray. It is useful when one wants to have faster Document retrieval on embeddings, i.e. .match(), .find().

Tip

This feature requires annlite. You can install it via pip install "docarray[annlite]".

Usage

One can instantiate a DocumentArray with Annlite storage like so:

from docarray import DocumentArray

da = DocumentArray(storage='annlite', config={'n_dim': 10})

The usage would be the same as the ordinary DocumentArray.

To access a DocumentArray formerly persisted, one can specify the data_path in config.

from docarray import DocumentArray

da = DocumentArray(storage='annlite', config={'data_path': './data', 'n_dim': 10})

da.summary()

Note that specifying the n_dim is mandatory before using Annlite as a backend for DocumentArray.

Other functions behave the same as in-memory DocumentArray.

Config

The following configs can be set:

Name	Description	Default
n_dim	Number of dimensions of embeddings to be stored and retrieved	This is always required
data_path	The data folder where the data is located	A random temp folder
metric	Distance metric to be used during search. Can be ‘cosine’, ‘dot’ or ‘euclidean’	‘cosine’
ef_construction	The size of the dynamic list for the nearest neighbors (used during the construction)	None, defaults to the default value in the AnnLite package*
ef_search	The size of the dynamic list for the nearest neighbors (used during the search)	None, defaults to the default value in the AnnLite package*
max_connection	The number of bi-directional links created for every new element during construction.	None, defaults to the default value in the AnnLite package*

*You can check the default values in the AnnLite source code

Vector search with filter

Search with .find can be restricted by user-defined filters. Filters can be constructed following the guidelines provided in the AnnLite source repository.

Example of .find with a filter only

Consider you store Documents with a certain tag price into annlite and you want to retrieve all Documents with price lower or equal to some max_price value.

You can index such Documents as follows:

from docarray import Document, DocumentArray
import numpy as np

n_dim = 3
da = DocumentArray(
    storage='annlite',
    config={
        'n_dim': n_dim,
        'columns': {'price': 'float'},
    },
)

with da:
    da.extend([Document(id=f'r{i}', tags={'price': i}) for i in range(10)])

print('\nIndexed Prices:\n')
for price in da[:, 'tags__price']:
    print(f'\t price={price}')

Then you can retrieve all documents whose price is lower than or equal to max_price by applying the following filter:

max_price = 3
n_limit = 4

filter = {'price': {'$lte': max_price}}
results = da.find(filter=filter)

print('\n Returned examples that verify filter "price at most 3":\n')
for price in results[:, 'tags__price']:
    print(f'\t price={price}')

This would print

 Returned examples that satisfy condition "price at most 3":

	 price=0
	 price=1
	 price=2
	 price=3

Example of .find with query vector and filter

Consider Documents with embeddings [0,0,0] up to [9,9,9] where the document with embedding [i,i,i] has as tag price with value i. We can create such example with the following code:

from docarray import Document, DocumentArray
import numpy as np

n_dim = 3
metric = 'Euclidean'

da = DocumentArray(
    storage='annlite',
    config={'n_dim': n_dim, 'columns': {'price': 'float'}, 'metric': metric},
)

with da:
    da.extend(
        [
            Document(id=f'r{i}', embedding=i * np.ones(n_dim), tags={'price': i})
            for i in range(10)
        ]
    )

Consider we want the nearest vectors to the embedding [8. 8. 8.], with the restriction that prices must follow a filter. As an example, let’s consider that retrieved documents must have price value lower or equal than max_price. We can encode this information in annlite using filter = {'price': {'$lte': max_price}}.

Then the search with the proposed filter can be implemented and used with the following code:

max_price = 7
n_limit = 4

np_query = np.ones(n_dim) * 8
print(f'\nQuery vector: \t{np_query}')

filter = {'price': {'$lte': max_price}}
results = da.find(np_query, filter=filter, limit=n_limit)
print('\nEmbeddings Nearest Neighbours with "price" at most 7:\n')
for embedding, price in zip(results.embeddings, results[:, 'tags__price']):
    print(f'\tembedding={embedding},\t price={price}')

This would print:

Query vector: 	[8. 8. 8.]

Embeddings Nearest Neighbours with "price" at most 7:

	embedding=[7. 7. 7.],	 price=7
	embedding=[6. 6. 6.],	 price=6
	embedding=[5. 5. 5.],	 price=5
	embedding=[4. 4. 4.],	 price=4