Using CONN
==========

``CONN`` evaluates connectivity between prototypes rather than relying only on centroid distances.
Its batch and incremental modes therefore require an explicit choice of prototype backend.

Batch mode
----------

The default backend is ``MiniBatchKMeans`` and supports batch input only:

.. code-block:: python

   import cvi

   index = cvi.CONN(
       model_type="MiniBatchKMeans",
       kmeans_k=8,
       kmeans_kwargs={"random_state": 0, "n_init": 10},
   )
   value = index.get_cvi(samples, labels)

``model_type="KMeans"`` selects ordinary scikit-learn KMeans.
For either KMeans backend, ``kmeans_k`` may be a positive integer applied to every input label or a dictionary keyed by the original integer labels.
Counts larger than a label's sample count are capped automatically.
Do not pass ``n_clusters`` in ``kmeans_kwargs``; configure it through ``kmeans_k``.

With the default ``normalize_batch=True``, each feature is min-max normalized over the full batch before prototypes are fitted.
Disable this only when the data are already on the intended scale.

Incremental mode
----------------

Incremental updates require the FuzzyART backend:

.. code-block:: python

   index = cvi.CONN(model_type="Fuzzy")

   for sample, label in stream:
       value = index.get_cvi(sample, int(label))

Incremental samples are not normalized by the class because future feature
bounds are unknown. They must normally already lie in ``[0, 1]``.
The default ``check_incremental_normalized=True`` validates that assumption; disabling the
check does not normalize the samples.

The FuzzyART parameters ``rho``, ``alpha``, ``beta``, and ``match_tracking`` control prototype formation and are passed to the underlying ART model.
Streamorder and those parameters can therefore affect the learned prototypes and the resulting criterion trajectory.

Limitations
-----------

``CONN`` does not currently implement :meth:`cvi.CVI.remove` or
:meth:`cvi.CVI.merge`.
A KMeans-backed object also rejects incremental samples.
Use a new object when changing backend or evaluating another independent partition.