Fix BOCD API example

Author: jaime-cespedes-sisniega

frouros/detectors/concept_drift/streaming/change_detection/bocd.py

@@ -2,12 +2,13 @@
 
 import abc
 import copy
-from typing import Union, Optional
+from typing import List, Union, Optional
 
 import numpy as np  # type: ignore
 from scipy.special import logsumexp  # type: ignore
 from scipy.stats import norm  # type: ignore
 
+from frouros.callbacks.streaming.base import BaseCallbackStreaming
 from frouros.detectors.concept_drift.streaming.change_detection.base import (
     BaseChangeDetection,
     BaseChangeDetectionConfig,
@@ -122,8 +123,8 @@ def var_params(self):
 class BOCDConfig(BaseChangeDetectionConfig):
     """BOCD (Bayesian Online Change Detection) [adams2007bayesian]_ configuration.
 
-    :param model: BOCD model, (e.g. :class:`frouros.detectors.concept_drift.streaming.change_detection.bocd.GaussianUnknownMean`)
-    :type model: BaseBOCDModel
+    :param model: BOCD model, defaults to None. If None, :class:`frouros.detectors.concept_drift.streaming.change_detection.bocd.GaussianUnknownMean` is used.
+    :type model: Optional[BaseBOCDModel]
     :param hazard: hazard value, defaults to 0.01
     :type hazard: float
     :param min_num_instances: minimum numbers of instances to start looking for changes, defaults to 30
@@ -136,9 +137,11 @@ class BOCDConfig(BaseChangeDetectionConfig):
         arXiv preprint arXiv:0710.3742 (2007).
     """  # noqa: E501
 
+    model_type = GaussianUnknownMean
+
     def __init__(  # noqa: D107
         self,
-        model: BaseBOCDModel = GaussianUnknownMean,  # type: ignore
+        model: Optional[BaseBOCDModel] = None,  # type: ignore
         hazard: float = 0.01,
         min_num_instances: int = 30,
     ) -> None:
@@ -166,20 +169,23 @@ def model(self, model: BaseBOCDModel) -> None:
         :type model: BaseBOCDModel
         :raises TypeError: if model is not an instance of BaseModel
         """
-        if not isinstance(model, BaseBOCDModel):
-            raise TypeError(
-                f"model must be an instance of BaseModel, not {type(model)}"
-            )
-        self._model = model
+        if model is not None:
+            if not isinstance(model, BaseBOCDModel):
+                raise TypeError(
+                    f"model must be an instance of BaseModel, not {type(model)}"
+                )
+            self._model = model
+        else:
+            self._model = self.model_type()
 
 
 class BOCD(BaseChangeDetection):
     """BOCD (Bayesian Online Change Detection) [adams2007bayesian]_ detector.
 
-    :param config: configuration object of the detector
-    :type config: BOCDConfig
-    :param callbacks: list of callbacks, defaults to None
-    :type callbacks: list, optional
+    :param config: configuration object of the detector, defaults to None. If None, the default configuration of :class:`BOCDConfig` is used.
+    :type config: Optional[BOCDConfig]
+    :param callbacks: callbacks, defaults to None
+    :type callbacks: Optional[Union[BaseCallbackStreaming, List[BaseCallbackStreaming]]]
 
     :Note:
      Adapted from the implementation in https://github.com/gwgundersen/bocd.
@@ -192,14 +198,13 @@ class BOCD(BaseChangeDetection):
 
     :Example:
 
-    >>> from frouros.detectors.concept_drift import BOCD, BOCDConfig
-    >>> from frouros.detectors.concept_drift.streaming.change_detection.bocd import GaussianUnknownMean
+    >>> from frouros.detectors.concept_drift import BOCD
     >>> import numpy as np
     >>> np.random.seed(seed=31)
     >>> dist_a = np.random.normal(loc=0.2, scale=0.01, size=1000)
     >>> dist_b = np.random.normal(loc=0.8, scale=0.04, size=1000)
     >>> stream = np.concatenate((dist_a, dist_b))
-    >>> detector = BOCD(config=BOCDConfig(model=GaussianUnknownMean()))
+    >>> detector = BOCD()
     >>> for i, value in enumerate(stream):
     ...     _ = detector.update(value=value)
     ...     if detector.drift:
@@ -211,9 +216,11 @@ class BOCD(BaseChangeDetection):
     config_type = BOCDConfig  # type: ignore
 
     def __init__(  # noqa: D107
-            self,
-            config: BOCDConfig,
-            callbacks: list = None,
+        self,
+        config: Optional[BOCDConfig] = None,
+        callbacks: Optional[
+            Union[BaseCallbackStreaming, List[BaseCallbackStreaming]]
+        ] = None,
     ) -> None:
         super().__init__(
             config=config,