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{{Short description|Metric of clustering solutions quality}}
 
[[File:DBCV clustering evaluation.png|thumb|500px|In each graph, an increasing level of noise is introduced to the initial data, which consist of two well-defined semicircles. As the noise increases and thus the overlap between the two groups, the value of the DBCV index progressively decreases. Image released under MIT license.<ref name = felsiq>GitHub.
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== Density-Based Clustering Validation (DBCV) ==
 
[[File:DBCV clustering evaluation.png|thumb|500px|In each graph, an increasing level of noise is introduced to the initial data, which consist of two well-defined semicircles. As the noise increases and thus the overlap between the two groups, the value of the DBCV metric progressively decreases.Image released under MIT license <ref name = felsiq>GitHub
FelSiq/DBCV Fast Density-Based Clustering Validation (DBCV) Python
package -- https://github.com/FelSiq/DBCV</ref>]]
 
 
'''Density-Based Clustering Validation (DBCV)''' is a metric designed to assess the quality of clustering solutions, particularly for density-based clustering algorithms like [[DBSCAN]], [[Mean shift]], and [[OPTICS]].
This metric is particularly suited for identifying concave and nested clusters, where traditional metrics such as the [[Silhouette (clustering)|Silhouette coefficient]], [[Davies–Bouldin index]], or [[Calinski–Harabasz index]] often struggle to provide meaningful evaluations.
 
Unlike traditional validation measures, which often rely on compact and well-separated clusters, DBCV index evaluates how well clusters are defined in terms of local density variations and structural coherence.
 
This metric was introduced in 2014 by by David Moulavi and colleagues in their work .<ref name = Moulavi>{{CiteCitation
| last last1 = Moulavi
| first first1 = DavoudDavid
| last2 = Jaskowiak
| first2 = Pablo A.
| last3 = Campello
| first3 = Ricardo J. G. B.
| last4 = Zimek
| first4 = Arthur
| last5 = Sander
| first5 = Jörg
| chapter = Density-Based Clustering Validation
| year = 2014
| title = Proceedings of the 2014 SIAM International Conference on Data Mining
| title = Density-based clustering validation
| journal = Proceedings of the 2014 SIAM International Conference on Data Mining
| doi = 10.1137/1.9781611973440.96
| pages = 839–847
| publisher = SIAM
| isbn = 978-1-61197-344-0
| url = https://www.dbs.ifi.lmu.de/~zimek/publications/SDM2014/DBCV.pdf
}}</ref>. It utilizes density connectivity principles to quantify clustering structures, making it especially effective at detecting arbitrarily shaped clusters in concave datasets, where traditional metrics may be less reliable.
 
The DBCV index has been employed for clustering analysis in bioinformatics,<ref name="Di Giovanni">{{Citation
| last= Di Giovanni
| first= Daniele
| year= 2023
| title= Using machine learning to explore shared genetic pathways and possible endophenotypes in autism spectrum disorder
| journal= Genes
| volume= 14
| issue= 2
| page= 313
| doi = 10.3390/genes14020313
| doi-access= free
| pmid= 36833240
| pmc= 9956345
}}</ref> ecology,<ref name="Poutaraud">{{Citation
| last= Poutaraud
| first= Joachim
| year= 2024
| title= Meta-Embedded Clustering (MEC): A new method for improving clustering quality in unlabeled bird sound datasets
| journal = Ecological Informatics
| volume= 82
| pages = 102687
| publisher = Elsevier
| doi = 10.1016/j.ecoinf.2024.102687
| doi-access= free
}}</ref> techno-economy,<ref name="Shim">{{Citation
| last= Shim
| first= Jaehyun
| year= 2022
| title= Techno-economic analysis of micro-grid system design through climate region clustering
| journal = Energy Conversion and Management
| volume= 274
| pages = 116411
| publisher = Elsevier
| doi = 10.1016/j.enconman.2022.116411
| bibcode= 2022ECM...27416411S
| url = https://www.sciencedirect.com/science/article/abs/pii/S019689042201189X
| url-access= subscription
}}</ref> and health informatics<ref name="Martinez">{{Citation
| last= Martínez
| first= Rubén Yáñez
| year= 2023
| title= Spanish Corpora of tweets about COVID-19 vaccination for automatic stance detection
| journal = Information Processing & Management
| volume= 60
| issue= 3
| pages = 103294
| publisher = Elsevier
| doi = 10.1016/j.ipm.2023.103294
| doi-access= free
}}</ref>
<ref>{{cite journal |
author= Chicco D. |
author2= Oneto L. |
author3= Cangelosi D. |
title = DBSCAN and DBCV application to open medical records heterogeneous data for identifying clinically significant clusters of patients with neuroblastoma |
journal = BioData Mining |
volume = 18 |
issue = 40 |
date = 2025 |
page = 1-17 |
doi = 10.1186/s13040-025-00455-8 |
doi-access=free|
pmc = 12164137 }}</ref>, as well as in numerous other fields.<ref name="Beer">{{cite arXiv |mode=cs2
| last= Beer
| first= Anna
| year= 2025
| title= DISCO: Internal Evaluation of Density-Based Clustering
| class= cs.LG
| eprint = 2503.00127
}}</ref>
<ref name="Veigel">{{Citation
| last= Veigel
| first= Nadja
| year= 2025
| title= Content analysis of multi-annual time series of flood-related Twitter (X) data
| journal = Natural Hazards and Earth System Sciences
| volume= 25
| issue= 2
| pages = 879–891
| publisher = Copernicus Publications Gottingen, Germany
| doi = 10.5194/nhess-25-879-2025
| doi-access= free
| bibcode= 2025NHESS..25..879V
| url = https://nhess.copernicus.org/articles/25/879/2025/
}}</ref>
 
== Definition ==
DBCV index evaluates clustering structures by analyzing the relationships between data points within and across clusters. Given a dataset <math>X = {x_1,x_2,...,x_n}</math>, a density-based algorithm partitions it into ''K '' clusters <math>{C_1,C_2,...,C_n}</math>. Each point belongs to a specific cluster, denoted as <math>Cluster(X_i)</math>
 
A key concept in DBCV index is the notion of density-connected paths.<ref>{{CiteCitation
| last = Ester
| first = M.
Line 35 ⟶ 126:
| title = Density-based Clustering
| journal = Encyclopedia of Database Systems
| pages = 795–799
| editor1-last = Liu
| editor1-first = L.
Line 44 ⟶ 136:
| doi = 10.1007/978-0-387-39940-9_605
| url = https://doi.org/10.1007/978-0-387-39940-9_605
| url-access= subscription
}}</ref>. Two points within the same cluster are considered density-connected if there exists a sequence of intermediate points linking them, where each consecutive pair meets a predefined density criterion. The '''density-based distance''' between two points is determined by identifying the optimal path that minimizes the maximum local reachability distance along its trajectory.
}}</ref> Two points within the same cluster are considered density-connected if there exists a sequence of intermediate points linking them, where each consecutive pair meets a predefined density criterion. The '''density-based distance''' between two points is determined by identifying the optimal path that minimizes the maximum local reachability distance along its trajectory.
 
DBCV extends the [[Silhouette (clustering)|Silhouette coefficient]] by redefining cluster cohesion and separation using density-based distances:
 
DBCV index extends the [[Silhouette (clustering)|Silhouette coefficient]] by redefining cluster cohesion and separation using density-based distances:
 
* '''Within-cluster density distance''' measures how closely a point is related to other members of its cluster:
 
 
<math>
Line 56 ⟶ 147:
</math>
 
* '''Nearest-cluster density distance''' quantifies how far a point is from the closest external cluster:
 
 
<math>
b_i = \min_{{C \neq C_{\text{cluster}(x_i)} \atop C \in \{C_1,\dots,C_k\}}}
\left( \frac{1}{|C|} \sum_{x_j \in C} d_{\text{density}}(x_i, x_j) \right).
</math>
 
 
Using these measures, the '''DBCV index''' is computed as:
Line 73 ⟶ 162:
== Explanation ==
 
DBCV index values range between -1−1 and +1:
 
* +1: Strongly cohesive and well-separated clusters.
* 0: Ambiguous clustering structure.
* -1−1: Poorly formed clusters or incorrect assignments.
 
By leveraging density-based distances instead of traditional [[Euclidean distance|Euclidean measures]], DBCV index provides a more robust evaluation of clustering performance in datasets with irregular or non-spherical distributions.<ref name = Moulavi />
 
== References ==
By leveraging density-based distances instead of traditional [[Euclidean distance|Euclidean measures]], DBCV provides a more robust evaluation of clustering performance in datasets with irregular or non-spherical distributions<ref name = Moulavi />
*{{Citation
.
| last1 = Moulavi
| first1 = David
| last2 = Jaskowiak
| first2 = Pablo A.
| last3 = Campello
| first3 = Ricardo J. G. B.
| last4 = Zimek
| first4 = Arthur
| last5 = Sander
| first5 = Jörg
| chapter = Density-based clustering validation
| year = 2014
| title = Proceedings of the 2014 SIAM International Conference on Data Mining
| doi = 10.1137/1.9781611973440.96
| pages = 839–847
| publisher = SIAM
| isbn = 978-1-61197-344-0
| url = https://www.dbs.ifi.lmu.de/~zimek/publications/SDM2014/DBCV.pdf
| doi-access=free
}}
 
*{{Citation
== Implementations ==
| last1 = Chicco
| first1 = Davide
| last2 = Sabino
| first2 = Giuseppe
| last3 = Oneto
| first3 = Luca
| last4 = Jurman
| first4 = Giuseppe
| chapter = The DBCV index is more informative than DCSI, CDbw, and VIASCKDE indices for unsupervised clustering internal assessment of concave-shaped and density-based clusters
| year = 2025
| title = PeerJ Computer Science
| doi = 10.7717/peerj-cs.3095
| pages = 1-37
| publisher = PeerJ Inc.
| url = https://doi.org/10.7717/peerj-cs.3095
| doi-access=free
}}
 
== Implementations ==
* [https://github.com/christopherjenness/DBCV Python DBCV Implementation by Christopher Jennes]
* [https://github.com/FelSiq/DBCV Python DBCV Implementation by Felipe Alves Siqueira]
 
* [https://githubdoi.comorg/FelSiq10.32614/DBCVcran.package.dbcvindex PythonR DBCV Implementation by FelipePablo Andretta SilvaJaskowiak]
 
* [https://doi.org/10.32614/CRAN.package.DBCVindex R DBCV Implementation]
 
== See also ==
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== References ==
<references/>
 
{{Machine learning evaluation metrics}}
 
[[Category:Cluster analysis]]