If the vectors you are working with are provided as a list of floats, you can convert them into the compact BLOB format that `sqlite-vec` uses with [`struct.pack()`](https://docs.python.org/3/library/struct.html#struct.pack).
```python
import struct
def serialize(vector: List[float]) -> bytes:
""" serializes a list of floats into a compact "raw bytes" format """
return struct.pack('%sf' % len(vector), *vector)
embedding = [0.1, 0.2, 0.3, 0.4]
result = db.execute('select vec_length(?)', [serialize(embedding)]).fetchone()[0]
print(result) # 4
```
### NumPy Arrays
If your vectors are from `numpy` arrays, the Python SQLite package allows you to pass it along as-is. Make sure you convert your array elements to 32-bit floats with [`.astype(np.float32)`](https://numpy.org/doc/stable/reference/generated/numpy.ndarray.astype.html), as some embedding services will use `np.float64` elements.
Some features of `sqlite-vec` will require an up-to-date SQLite library. You can see what version of SQLite your Python environment uses with [`sqlite3.sqlite-version`](https://docs.python.org/3/library/sqlite3.html#sqlite3.sqlite_version), or with this one-line command:
Currently, **SQLite version 3.41 or higher** is recommended but not required. `sqlite-vec` will work with older version, but certain features and queries will only work correctly in >=3.41.
To "upgrade" the SQLite version your Python installation uses, you have a few options.
### Compile your own SQLite version
You can compile an up-to-date version of SQLite and use some system environment variables (like `LD_PRELOAD` and `DYLD_LIBRARY_PATH`) to force Python to use a different SQLite library. [This guide](https://til.simonwillison.net/sqlite/sqlite-version-macos-python) goes into this approach in more details.
Although compiling SQLite can be straightforward, there are a lot of different compilation options to consider, which makes it confusing. This also doesn't work with Windows, which statically compiles its own SQLite library.
### Use `pysqlite3`
[`pysqlite3`](https://github.com/coleifer/pysqlite3) is a 3rd party PyPi package that bundles an up-to-date SQLite library as a separate pip package.
While it's mostly compatible with the Python `sqlite3` module, there are a few rare edge cases where the APIs don't match.
### Upgrading your Python version
Sometimes installing a latest version of Python will "magically" upgrade your SQLite version as well. This is a nuclear option, as upgrading Python installations can be quite the hassle, but most Python 3.12 builds will have a very recent SQLite version.