CalinskiHarabasz¶
Calinski-Harabasz index (CH).
The Calinski-Harabasz index (CH) index measures the criteria simultaneously with the help of average between and within cluster sum of squares.
-
The numerator reflects the degree of separation in the way of how much centers are spread.
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The denominator corresponds to compactness, to reflect how close the in-cluster objects are gathered around the cluster center.
Attributes¶
-
bigger_is_better
Indicates if a high value is better than a low one or not.
Examples¶
>>> from river import cluster
>>> from river import stream
>>> from river import metrics
>>> X = [
... [1, 2],
... [1, 4],
... [1, 0],
... [4, 2],
... [4, 4],
... [4, 0],
... [-2, 2],
... [-2, 4],
... [-2, 0]
... ]
>>> k_means = cluster.KMeans(n_clusters=3, halflife=0.4, sigma=3, seed=0)
>>> metric = metrics.cluster.CalinskiHarabasz()
>>> for x, _ in stream.iter_array(X):
... k_means = k_means.learn_one(x)
... y_pred = k_means.predict_one(x)
... metric = metric.update(x, y_pred, k_means.centers)
>>> metric
CalinskiHarabasz: 6.922666
Methods¶
get
Return the current value of the metric.
revert
Revert the metric.
Parameters
- x
- y_pred
- centers
- sample_weight – defaults to
1.0
update
Update the metric.
Parameters
- x
- y_pred
- centers
- sample_weight – defaults to
1.0
works_with
Indicates whether or not a metric can work with a given model.
Parameters
- model (river.base.estimator.Estimator)
References¶
-
Calinski, T., Harabasz, J.-A. (1974). A Dendrite Method for Cluster Analysis. Communications in Statistics 3(1), 1 - 27. DOI: 10.1080/03610927408827101 ↩