Similarity Measure For Clustering Research Articles

Timing based clustering of childhood BMI trajectories reveals differential maturational patterns; Study in the Northern Finland Birth Cohorts 1966 and 1986.

Children's biological age does not always correspond to their chronological age. In the case of BMI trajectories, this can appear as phase variation, which can be seen as shift, stretch, or shrinking between trajectories. With maturation thought of as a process moving towards the final state - adult BMI, we assessed whether children can be divided into latent groups reflecting similar maturational age of BMI. The groups were characterised by early factors and time-related features of the trajectories. We used data from two general population birth cohort studies, Northern Finland Birth Cohorts 1966 and 1986 (NFBC1966 and NFBC1986). Height (n = 6329) and weight (n = 6568) measurements were interpolated in 34 shared time points using B-splines, and BMI values were calculated between 3 months to 16 years. Pairwise phase distances of 2999 females and 3163 males were used as a similarity measure in k-medoids clustering. We identified three clusters of trajectories in females and males (Type 1: females, n = 1566, males, n = 1669; Type 2: females, n = 1028, males, n = 973; Type 3: females, n = 405, males, n = 521). Similar distinct timing patterns were identified in males and females. The clusters did not differ by sex, or early growth determinants studied. Trajectory cluster Type 1 reflected to the shape of what is typically illustrated as the childhood BMI trajectory in literature. However, the other two have not been identified previously. Type 2 pattern was more common in the NFBC1966 suggesting a generational shift in BMI maturational patterns.

CLUSTERING IN COMPILING INVESTMENT PORTFOLIOS

Clustering is an effective tool for diversifying investments, reducing risk and identifying new opportunities. Clustering plays a key role in data analysis, allowing you to group objects with similar characteristics. This study examines the application of clustering to the tasks of forming and optimizing investment portfolios. The paper presents two clustering methods: K-medoids and fuzzy clustering (C-means). K-medoids divides assets into clusters by correlation, and C-means allows assets to belong to several clusters with varying degrees. The article analyzes various clustering methods in the context of the stock market. Similarity measures for stock clustering are compared. The K-means algorithm for clustering companies by time series is presented. Chaotic cartographic clustering is used to analyze the dynamics of the stock market. The TreeGNG algorithm is used to identify stock market sectors. The HRK method has been developed to predict short-term changes in stock prices. The application of data mining methods to predict stock market trends is discussed. The K-means and C-means methods for clustering banking and energy companies are compared. The effectiveness of the SOM-SVR hybrid approach for predicting price dynamics and volatility is demonstrated. C-means combines with artificial neural networks to improve the accuracy of stock market forecasting. The study demonstrates the potential of various clustering methods in the context of compiling and optimizing investment portfolios.

A Data-Driven Approach for Generating Vortex-Shedding Regime Maps for an Oscillating Cylinder

This study presents a data-driven approach for generating vortex-shedding maps, which are vital for predicting flow structures in vortex-induced vibration (VIV) wind energy extraction devices, while addressing the computational and complexity limitations of traditional methods. The approach employs unsupervised clustering techniques on subsequences extracted using the matrix profile method from local flow measurements in the wake of an oscillating circular cylinder generated from 2-dimensional computational fluid dynamics simulations of VIV. The proposed clustering methods were validated by reproducing a benchmark map produced at a low Reynolds number (Re = 4000) and then extended to a higher Reynolds number (Re = 10,000) to gain insights into the complex flow regimes. The multi-step clustering methods used density-based and k-Means clustering for the pre-clustering stage and agglomerative clustering using dynamic time warping (DTW) as the similarity measure for final clustering. The clustering methods achieved exceptional performance at high-Reynolds-number flow, with scores in the silhouette index (0.4822 and 0.4694) and Dunn index (0.3156 and 0.2858) demonstrating the accuracy and versatility of the hybrid clustering methods. This data-driven approach enables the generation of more accurate and feasible maps for vortex-shedding applications, which could improve the design and optimization of VIV wind energy harvesting systems.

Hierarchical Clustering-Based Framework for Interconnected Power System Contingency Analysis

This paper investigates a conceptual, theoretical framework for power system contingency analysis based on agglomerative hierarchical clustering. The security and integrity of modern power system networks have received considerable critical attention, and contingency analysis plays a vital role in assessing the adverse effects of losing a single element or more on the integrity of the power system network. However, the number of possible scenarios that should be investigated would be enormous, even for a small network. On the other hand, artificial intelligence (AI) techniques are well known for their remarkable ability to deal with massive data. Rapid developments in AI have led to a renewed interest in its applications in many power system studies over the last decades. Hence, this paper addresses the application of the hierarchical clustering algorithm supported by principal component analysis (PCA) for power system contingency screening and ranking. The study investigates the hierarchy clustering under different clustering numbers and similarity measures. The performance of the developed framework has been evaluated using the IEEE 24-bus test system. The simulation results show the effectiveness of the proposed framework for contingency analysis.

Spectral clustering and fuzzy similarity measure for images segmentation

En los algoritmos de segmentación de imágenes mediante agrupamiento espectral, debido al tamaño de las imágenes, la carga computacional para la construcción de la matriz de similitud y la solución al problema de valores propios para la matriz laplaciana son altos. Además, la medida de similitud más utilizada es el kernel gaussiano, el cual presenta problemas con distribuciones de datos irregulares. Este trabajo propone realizar una presegmentación o diezmado mediante superpíxeles con el algoritmo Simple Linear Iterative Clustering, para disminuir el costo computacional y construir la matriz de similaridad con una medida difusa basada en el clasificador Fuzzy C-Means, que proporciona al algoritmo una mayor robustez frente a imágenes con distribuciones complejas; mediante agrupamiento espectral se determina la segmentación final. Experimentalmente, se comprobó que el enfoque propuesto obtiene segmentaciones adecuadas, buenos resultados de agrupamiento y una precisión comparable respecto a cinco algoritmos, midiendo el desempeño bajo cuatro métricas de validación.

Generalized [formula omitted]-means in GLMs with applications to the outbreak of COVID-19 in the United States

Generalized k-means can be combined with any similarity or dissimilarity measure for clustering. Using the well known likelihood ratio or F-statistic as the dissimilarity measure, a generalized k-means method is proposed to group generalized linear models (GLMs) for exponential family distributions. Given the number of clusters k, the proposed method is established by the uniform most powerful unbiased (UMPU) test statistic for the comparison between GLMs. If k is unknown, then the proposed method can be combined with generalized liformation criterion (GIC) to automatically select the best k for clustering. Both AIC and BIC are investigated as special cases of GIC. Theoretical and simulation results show that the number of clusters can be correctly identified by BIC but not AIC. The proposed method is applied to the state-level daily COVID-19 data in the United States, and it identifies 6 clusters. A further study shows that the models between clusters are significantly different from each other, which confirms the result with 6 clusters.

RatioRF: a novel measure for Random Forest clustering based on the Tversky's Ratio model

In this paper we propose RatioRF, a novel Random Forest-based similarity measure for clustering. We build upon Tversky's ratio model definition of similarity and specialize it to the Random Forest case. We study some properties of the proposed axiomatic similarity measure and present an extensive experimental clustering analysis involving different datasets and configurations. Results confirm that RatioRF represents a good alternative to other similar measures for clustering recently studied in the literature.

Disconnected Maximum Common Substructures under Constraints.

The maximum common substructure (MCS) problem is an important, well-studied problem in cheminformatics. It is applied in several application scenarios like molecule superimposition and scaffold detection or as a similarity measure in virtual screening and clustering. In many cases, the connected MCS is preferred since it is faster to calculate and a highly fragmented MCS is not very meaningful from a chemical point of view. Nevertheless, a disconnected MCS (dMCS) can be very instructive if it consists of reasonably sized molecular parts connected by variable groups. We present a new algorithm named RIMACS, which is able to calculate the dMCS under constraints. We can control the maximum number of connected components and their minimal size using a modified local substructure mapping approach. A formal proof of correctness is provided as well as extended runtime evaluations on chemical data. The evaluation of RIMACS shows that a small number of connected components helps us to improve MCS similarity in a meaningful way while keeping the runtime requirements in a reasonable range.

Applications of picture fuzzy similarity measures in pattern recognition, clustering, and MADM

Picture fuzzy set (PFS) is a direct extension of fuzzy sets (FSs) and intuitionistic fuzzy sets (IFSs) and is quite powerful than FSs and IFSs in expressing the uncertainty and vagueness in our daily life problems. In this article, we propose some new similarity measures for PFSs which are capable of distinguishing highly similar but inconsistent PFSs. We also demonstrate their applications in pattern recognition using some illustrative examples as well as with real data. We assess the performance of the proposed measures using the concept of degree of confidence. We also extend the maximum spanning tree (MST) clustering algorithm to PF (picture fuzzy)-environment and propose a picture fuzzy maximum spanning tree (PFMST) clustering method. Further, we introduce a new attribute weight determining formula based on PF-similarity measures in multi-attribute decision-making (MADM) problem. We also establish the superiority of our proposed PF-similarity measures over some existing PF-similarity measures in view of the structured linguistic variables.

A set theory based similarity measure for text clustering and classification

Similarity measures have long been utilized in information retrieval and machine learning domains for multi-purposes including text retrieval, text clustering, text summarization, plagiarism detection, and several other text-processing applications. However, the problem with these measures is that, until recently, there has never been one single measure recorded to be highly effective and efficient at the same time. Thus, the quest for an efficient and effective similarity measure is still an open-ended challenge. This study, in consequence, introduces a new highly-effective and time-efficient similarity measure for text clustering and classification. Furthermore, the study aims to provide a comprehensive scrutinization for seven of the most widely used similarity measures, mainly concerning their effectiveness and efficiency. Using the K-nearest neighbor algorithm (KNN) for classification, the K-means algorithm for clustering, and the bag of word (BoW) model for feature selection, all similarity measures are carefully examined in detail. The experimental evaluation has been made on two of the most popular datasets, namely, Reuters-21 and Web-KB. The obtained results confirm that the proposed set theory-based similarity measure (STB-SM), as a pre-eminent measure, outweighs all state-of-art measures significantly with regards to both effectiveness and efficiency.

Metaheuristic-based possibilistic multivariate fuzzy weighted c-means algorithms for market segmentation

This study proposed the metaheuristic-based possibilistic multivariate fuzzy weighted c-means (PMFWCM) algorithm for clustering mixed data PMFWCM algorithm itself is normally used for numerical data. To implement in the real application of market segmentation, where the data usually contains both numerical and categorical attributes model improvement is a need. First, the distance between two mixed-attribute objects is calculated by using the object–cluster similarity measure. Then, three metaheuristics, i.e., genetic algorithm (GA), particle swarm optimization algorithm (PSO), and sine cosine algorithm (SCA), are employed to integrate with the PMFWCM algorithm for cluster analysis. This combination aims to improve the clustering performance of the PMFWCM algorithm and to make the clustering results more stable. To cluster a real-world dataset certainly, the experiment with benchmark datasets from UCI machine learning repository is conducted to verify the performance of the proposed algorithms. The experiment results show that the clustering performance of the SCA-PMFWCM, GA-PMFWCM and PSO-PMFWCM algorithms are better than that of the PMFWCM algorithm. Moreover, from case study results, the SCA-PMFWCM algorithm gives the smallest sum of squared error and computational time compared with the GA-PMFWCM, PSO-PMFWCM, and PMFWCM algorithms.

Subtractive clustering and phase correlation similarity measure for endmember extraction

Target identification using Remote Sensing techniques saves time, cost and reduces difficulties in field investigation. The endmember is a reference spectral response of a pure pixel in the hyperspectral image and is used for object identification/classification from hyperspectral data. Quality of endmembers selected influences classification accuracy. Though there have been several algorithms proposed for endmember extraction, choosing a benchmark algorithm requires further investigation. To the best of our knowledge, similarity measures have not been explored much in the extraction of spectrally distinct signatures called endmembers. In this paper, we propose a similarity measures based subtractive clustering algorithm (SM-SCA) for endmember extraction. The objective of this paper is to explore the applicability of a SM-SCA and effectiveness of different similarity measures in endmember extraction and to compare it’s performance with classical endmember extraction algorithms. Implementation on airborne hyperspectral (Samson data and AVIRIS data over Cuprite region) and synthetic data proves that SM-SCA is capable of extracting endmembers of all the materials identified in the data, with appropriate similarity measure. Experimental results show that (i) the similarity measures are potential not only to discriminate but also in extraction of different endmember signatures and (ii) the proposed SM-SCA with phase correlation similarity measure perform comparable to the classical endmember extraction algorithms in identifying endmembers.

Lag penalized weighted correlation for time series clustering

BackgroundThe similarity or distance measure used for clustering can generate intuitive and interpretable clusters when it is tailored to the unique characteristics of the data. In time series datasets generated with high-throughput biological assays, measurements such as gene expression levels or protein phosphorylation intensities are collected sequentially over time, and the similarity score should capture this special temporal structure.ResultsWe propose a clustering similarity measure called Lag Penalized Weighted Correlation (LPWC) to group pairs of time series that exhibit closely-related behaviors over time, even if the timing is not perfectly synchronized. LPWC aligns time series profiles to identify common temporal patterns. It down-weights aligned profiles based on the length of the temporal lags that are introduced. We demonstrate the advantages of LPWC versus existing time series and general clustering algorithms. In a simulated dataset based on the biologically-motivated impulse model, LPWC is the only method to recover the true clusters for almost all simulated genes. LPWC also identifies clusters with distinct temporal patterns in our yeast osmotic stress response and axolotl limb regeneration case studies.ConclusionsLPWC achieves both of its time series clustering goals. It groups time series with correlated changes over time, even if those patterns occur earlier or later in some of the time series. In addition, it refrains from introducing large shifts in time when searching for temporal patterns by applying a lag penalty. The LPWC R package is available at https://github.com/gitter-lab/LPWC and CRAN under a MIT license.

A Novel Cosine Similarity Like Data Clustering Method for Effective Data Classification in Data Mining

In data mining ample techniques use distance based measures for data clustering. Improving clustering performance is the fundamental goal in cluster domain related tasks. Many techniques are available for clustering numerical data as well as categorical data. Clustering is an unsupervised learning technique and objects are grouped or clustered based on similarity among the objects. A new cluster similarity finding measure, which is cosine like cluster similarity measure (CLCSM), is proposed in this paper. The proposed cluster similarity measure is used for data classification. Extensive experiments are conducted by taking UCI machine learning datasets. The experimental results have shown that the proposed cosinelike cluster similarity measure is superior to many of the existing cluster similarity measures for data classification.

Joint Robust Multi-view Spectral Clustering

Current multi-view clustering algorithms use multistage strategies to conduct clustering, or require cluster number or similarity matrix prior, or suffer influence of irrelevant features and outliers. In this paper, we propose a Joint Robust Multi-view (JRM) spectral clustering algorithm that considers information from all views of the multi-view dataset to conduct clustering and solves the issues, such as initialization, cluster number determination, similarity measure, feature selection, and outlier reduction around clustering, in a unified way. The optimal performance could be reached when all views are considered and the separated stages are combined in a unified way. Experiments have been performed on six real-world benchmark datasets and our proposed JRM algorithm outperforms the comparison clustering algorithms in terms of two evaluation metrics for clustering algorithms including accuracy and purity.

An evaluation of the efficiency of similarity functions in density-based clustering of spatial trajectories

ABSTRACTSpatiotemporal movement pattern discovery has stimulated considerable interest due to its numerous applications, including data analysis, machine learning, data segmentation, data reduction, abnormal behaviour detection, noise filtering, and pattern recognition. Trajectory clustering is among the most widely used approaches of extracting interesting patterns in large trajectory datasets. In this paper, regarding the optimal performance of density-based clustering, we present a comparison between eight similarity measures in density-based clustering of moving objects’ trajectories. In particular, Distance Functions such as Euclidean, L1, Hausdorff, Fréchet, Dynamic Time Warping (DTW), Longest Common SubSequence (LCSS), Edit Distance on Real signals (EDR), and Edit distance with Real Penalty (ERP) are applied in DBSCAN on three different datasets with varying characteristics. Also, experimental results are evaluated using both internal and external indices. Furthermore, we propose two modified validation measures for density-based trajectory clustering, which can deal with arbitrarily shaped clusters with different densities and sizes. These proposed measures were aimed at evaluating trajectory clusters effectively in both spatial and spatio-temporal aspects. The evaluation results show that choosing an appropriate Distance Function is dependent on data and its movement parameters. However, in total, Euclidean distance proves to show superiority over the other Distance Functions regarding the Purity index and EDR distance can provide better performance in terms of spatial and spatio-temporal quality of clusters. Finally, in terms of computation time and scalability, Euclidean, L1, and LCSS are the most efficient Distance Functions.

Integral Curve Clustering and Simplification for Flow Visualization: A Comparative Evaluation.

Unsupervised clustering techniques have been widely applied to flow simulation data to alleviate clutter and occlusion in the resulting visualization. However, there is an absence of systematic guidelines for users to evaluate (both quantitatively and visually) the appropriate clustering technique and similarity measures for streamline and pathline curves. In this work, we provide an overview of a number of prevailing curve clustering techniques. We then perform a comprehensive experimental study to qualitatively and quantitatively compare these clustering techniques coupled with popular similarity measures used in the flow visualization literature. Based on our experimental results, we derive empirical guidelines for selecting the appropriate clustering technique and similarity measure given the requirements of the visualization task. We believe our work will inform the task of generating meaningful reduced representations for large-scale flow data and inspire the continuous investigation of a more refined guidance on clustering technique selection.

The impact of learner metacognition and goal orientation on problem-solving in a serious game environment

To understand the impact of learner metacognition and goal orientation on problem-solving, this study investigated 159 undergraduate students’ metacognition, goal orientations, and their problem-solving performances and processes in a laboratory setting using a Serious Game (SG) environment that adopts problem-based learning (PBL) pedagogy to teach space science. Utilizing cluster analysis, multiple regression, similarity measure and data visualization, this study analyzed multiple data sources, including computer log data, problem-solving performance scores, and survey data. The results show that both learner metacognition and goal orientation affected problem-solving. The findings of this study offer insights of how learner characteristics impact on problem-solving in SG environments with PBL pedagogy. It also contributes to understanding the design of SG environments to benefit learners based on their metacognitive levels.

Element-centric clustering comparison unifies overlaps and hierarchy

Clustering is one of the most universal approaches for understanding complex data. A pivotal aspect of clustering analysis is quantitatively comparing clusterings; clustering comparison is the basis for many tasks such as clustering evaluation, consensus clustering, and tracking the temporal evolution of clusters. In particular, the extrinsic evaluation of clustering methods requires comparing the uncovered clusterings to planted clusterings or known metadata. Yet, as we demonstrate, existing clustering comparison measures have critical biases which undermine their usefulness, and no measure accommodates both overlapping and hierarchical clusterings. Here we unify the comparison of disjoint, overlapping, and hierarchically structured clusterings by proposing a new element-centric framework: elements are compared based on the relationships induced by the cluster structure, as opposed to the traditional cluster-centric philosophy. We demonstrate that, in contrast to standard clustering similarity measures, our framework does not suffer from critical biases and naturally provides unique insights into how the clusterings differ. We illustrate the strengths of our framework by revealing new insights into the organization of clusters in two applications: the improved classification of schizophrenia based on the overlapping and hierarchical community structure of fMRI brain networks, and the disentanglement of various social homophily factors in Facebook social networks. The universality of clustering suggests far-reaching impact of our framework throughout all areas of science.

K-means 클러스터링 방법과 유사도 측정 기반의 채팅 말뭉치 반자동 확장 방법

본 논문에서는 영화 자막, 극 대본과 같이 대량의 발화 데이터를 이용하여 채팅 말뭉치를 반자동으로 확장하는 방법을 제안한다. 채팅 말뭉치 확장을 위해 미리 구축된 채팅 말뭉치와 유사도 기법을 이용하여 채팅 유사도를 구하고, 채팅 유사도가 실험을 통해 얻은 임계값보다 크다면 올바른 채팅 쌍이라고 판단하였다. 본 논문에서 제안하는 것은 형태소 단위 임베딩 벡터와 합성곱 신경망 모델을 이용하여 발화 단위 표상을 생성하는 것이다. 그리고 반자동 구축 모델의 속도를 개선하기 위해서 K-means 클러스터링 방법을 적용하여 채팅 말뭉치를 군집, 계산량을 줄일 것을 제안한다. 그 결과 기본 발화 단위 표상생성 방법인 TF를 이용하는 것보다 정확률, 재현율, F1에서 각각 5,16%p, 6.09%p, 5.73%p 각각 상승하여 61.28%, 53.19%, 56.94%의 성능을 도출하였다. 그리고 속도 개선을 위해 발화를 클러스터링하여 속도 면에서도 103배 향상된 채팅 말뭉치 반자동 구축 모델을 구축할 수 있었다.