Full text search engine for Python
"Sphinx does not have a Python API"

is not true. Download the release and look at sphinx/api/sphinxapi.py
I use it myself and I'm pretty happy with it. The documentation is for PHP only but the Python API uses the exact same names for all functions.
I'm searching for a Python full text search engine.
I took a look at PyLucense, but I think that using a Java-based library in a Python project is not good. As I understand, Sphinx does not have a Python API.
Any ideas ?