Convert a collection of features to a fixed-dimensional matrix using the hashing trick.

Note, this requires Jina>=2.2.4.


Here I use FeatureHasher to hash each sentence of Pride and Prejudice into a 128-dim vector, and
then use .match to find top-K similar sentences.

from jina import Document, DocumentArray, Flow

# load <Pride and Prejudice by Jane Austen>
d = Document(uri='https://www.gutenberg.org/files/1342/1342-0.txt').convert_uri_to_text()

# cut into non-empty sentences store in a DA
da = DocumentArray(Document(text=s.strip()) for s in d.text.split('\n') if s.strip())

# use FeatureHasher in a Flow
f = Flow().add(uses='jinahub://FeatureHasher')

embed_da = DocumentArray()
with f:
    f.post('/', da, on_done=lambda req: embed_da.extend(req.docs), show_progress=True)

embed_da.match(embed_da, exclude_self=True, limit=5, normalization=(1, 0))
print('total sentences: ', len(embed_da))
for d in embed_da:
    for m in d.matches:
        print(m.scores['cosine'], m.text)

           [email protected][I]:πŸŽ‰ Flow is ready to use!
	πŸ”— Protocol: 		GRPC
	🏠 Local access:
	πŸ”’ Private network:
	🌐 Public address:
β Ή       DONE ━╸━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 0:00:01 100% ETA: 0 seconds 40 steps done in 1 second
total sentences:  12153
ο»ΏThe Project Gutenberg eBook of Pride and Prejudice, by Jane Austen
<jina.types.score.NamedScore ('value',) at 5798762768> *** END OF THE PROJECT GUTENBERG EBOOK PRIDE AND PREJUDICE ***
<jina.types.score.NamedScore ('value',) at 5798763472> *** START OF THE PROJECT GUTENBERG EBOOK PRIDE AND PREJUDICE ***
<jina.types.score.NamedScore ('value',) at 5798762448> production, promotion and distribution of Project Gutenberg-tm
<jina.types.score.NamedScore ('value',) at 5798762576> Pride and Prejudice
<jina.types.score.NamedScore ('value',) at 5798762512> By Jane Austen

This eBook is for the use of anyone anywhere in the United States and
<jina.types.score.NamedScore ('value',) at 5798762384> This eBook is for the use of anyone anywhere in the United States and
<jina.types.score.NamedScore ('value',) at 5798762512> by the awkwardness of the application, and at length wholly
<jina.types.score.NamedScore ('value',) at 5798762832> Elizabeth passed the chief of the night in her sister’s room, and
<jina.types.score.NamedScore ('value',) at 5798762704> the happiest memories in the world. Nothing of the past was
<jina.types.score.NamedScore ('value',) at 5798761680> charities and charitable donations in all 50 states of the United

In practice, you can implement matching and storing via an indexer inside Flow.
This example is only for demo purpose so any non-feature hashing related ops are implemented outside the Flow to avoid distraction.


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