NumPy decoding docs, plus extra tests for llm.encode/decode

!stable-docs

Refs https://discord.com/channels/823971286308356157/1128504153841336370/1151975583237034056

docs/embeddings/storage.md

@@ -20,3 +20,12 @@ def decode(binary):
 ```
 
 These functions are available as `llm.encode()` and `llm.decode()`.
+
+If you are using [NumPy](https://numpy.org/) you can decode one of these binary values like this:
+
+```python
+import numpy as np
+
+numpy_array = np.frombuffer(value, "<f4")
+```
+The `<f4` format string here ensures NumPy will treat the data as a little-endian sequence of 32-bit floats.

setup.py

@@ -51,6 +51,7 @@ setup(
     extras_require={
         "test": [
             "pytest",
+            "numpy",
             "requests-mock",
             "cogapp",
             "mypy",

tests/test_encode_decode.py

@@ -0,0 +1,19 @@
+import llm
+import pytest
+import numpy as np
+
+
+@pytest.mark.parametrize(
+    "array",
+    (
+        (0.0, 1.0, 1.5),
+        (3423.0, 222.0, -1234.5),
+    ),
+)
+def test_roundtrip(array):
+    encoded = llm.encode(array)
+    decoded = llm.decode(encoded)
+    assert decoded == array
+    # Try with numpy as well
+    numpy_decoded = np.frombuffer(encoded, "<f4")
+    assert tuple(numpy_decoded.tolist()) == array