Clustering
Salvatore (Sal) Magnone on LinkedIn: Breaking it Down: K-Means Clustering
We are pleased to announce, thanks to the acquisition of Latham BioPharm Group, we are accelerating in the Life Sciences sector with the creation of a Life Science Consulting division. Latham BioPharm Group founded in 1996 by Peter Latham, is one of the top Life Science Consulting specialty firms supporting Non-Dilutive Funding, Product Development, and Strategic decision-making for a wide range of sectors and clients. "Pete and I have agreed on a global goal, supported by significant financial resources, that will allow us to grow organically at more than 20% per year...." says Matthieu Courtecuisse, Founder and CEO of Sia Partners.
A Pipeline for Business Intelligence and Data-Driven Root Cause Analysis on Categorical Data
Thakar, Shubham, Kalbande, Dhananjay
Business intelligence (BI) is any knowledge derived from existing data that may be strategically applied within a business. Data mining is a technique or method for extracting BI from data using statistical data modeling. Finding relationships or correlations between the various data items that have been collected can be used to boost business performance or at the very least better comprehend what is going on. Root cause analysis (RCA) is discovering the root causes of problems or events to identify appropriate solutions. RCA can show why an event occurred and this can help in avoiding occurrences of an issue in the future. This paper proposes a new clustering + association rule mining pipeline for getting business insights from data. The results of this pipeline are in the form of association rules having consequents, antecedents, and various metrics to evaluate these rules. The results of this pipeline can help in anchoring important business decisions and can also be used by data scientists for updating existing models or while developing new ones. The occurrence of any event is explained by its antecedents in the generated rules. Hence this output can also help in data-driven root cause analysis.
Inv-SENnet: Invariant Self Expression Network for clustering under biased data
Singh, Ashutosh, Singh, Ashish, Masoomi, Aria, Imbiriba, Tales, Learned-Miller, Erik, Erdogmus, Deniz
Subspace clustering algorithms are used for understanding the cluster structure that explains the dataset well. These methods are extensively used for data-exploration tasks in various areas of Natural Sciences. However, most of these methods fail to handle unwanted biases in datasets. For datasets where a data sample represents multiple attributes, naively applying any clustering approach can result in undesired output. To this end, we propose a novel framework for jointly removing unwanted attributes (biases) while learning to cluster data points in individual subspaces. Assuming we have information about the bias, we regularize the clustering method by adversarially learning to minimize the mutual information between the data and the unwanted attributes. Our experimental result on synthetic and real-world datasets demonstrate the effectiveness of our approach.
Doubly Inhomogeneous Reinforcement Learning
Hu, Liyuan, Li, Mengbing, Shi, Chengchun, Wu, Zhenke, Fryzlewicz, Piotr
This paper studies reinforcement learning (RL) in doubly inhomogeneous environments under temporal non-stationarity and subject heterogeneity. In a number of applications, it is commonplace to encounter datasets generated by system dynamics that may change over time and population, challenging high-quality sequential decision making. Nonetheless, most existing RL solutions require either temporal stationarity or subject homogeneity, which would result in sub-optimal policies if both assumptions were violated. To address both challenges simultaneously, we propose an original algorithm to determine the ``best data chunks" that display similar dynamics over time and across individuals for policy learning, which alternates between most recent change point detection and cluster identification. Our method is general, and works with a wide range of clustering and change point detection algorithms. It is multiply robust in the sense that it takes multiple initial estimators as input and only requires one of them to be consistent. Moreover, by borrowing information over time and population, it allows us to detect weaker signals and has better convergence properties when compared to applying the clustering algorithm per time or the change point detection algorithm per subject. Empirically, we demonstrate the usefulness of our method through extensive simulations and a real data application.
Non-parametric Clustering of Multivariate Populations with Arbitrary Sizes
Bakam, Yves Ismaรซl Ngounou, Pommeret, Denys
We propose a clustering procedure to group K populations into subgroups with the same dependence structure. The method is adapted to paired population and can be used with panel data. It relies on the differences between orthogonal projection coefficients of the K density copulas estimated from the K populations. Each cluster is then constituted by populations having significantly similar dependence structures. A recent test statistic from Ngounou-Bakam and Pommeret (2022) is used to construct automatically such clusters. The procedure is data driven and depends on the asymptotic level of the test. We illustrate our clustering algorithm via numerical studies and through two real datasets: a panel of financial datasets and insurance dataset of losses and allocated loss adjustment expense.
MGTCOM: Community Detection in Multimodal Graphs
Dmitriev, E., Chekol, M. W., Wang, S.
Community detection is the task of discovering groups of nodes sharing similar patterns within a network. With recent advancements in deep learning, methods utilizing graph representation learning and deep clustering have shown great results in community detection. However, these methods often rely on the topology of networks (i) ignoring important features such as network heterogeneity, temporality, multimodality, and other possibly relevant features. Besides, (ii) the number of communities is not known a priori and is often left to model selection. In addition, (iii) in multimodal networks all nodes are assumed to be symmetrical in their features; while true for homogeneous networks, most of the real-world networks are heterogeneous where feature availability often varies. In this paper, we propose a novel framework (named MGTCOM) that overcomes the above challenges (i)--(iii). MGTCOM identifies communities through multimodal feature learning by leveraging a new sampling technique for unsupervised learning of temporal embeddings. Importantly, MGTCOM is an end-to-end framework optimizing network embeddings, communities, and the number of communities in tandem. In order to assess its performance, we carried out an extensive evaluation on a number of multimodal networks. We found out that our method is competitive against state-of-the-art and performs well in inductive inference.
10 Most Used Machine Learning Algorithms In Python With Code
Understanding what Artificial Intelligence is and learning how Machine Learning and Deep Learning power it, are overwhelming experiences. In ML, there is something called the "No Free Lunch" theorems which states that no machine learning algorithms works best for every problem, and it's particularly relevant for supervised learning. For example, you can't say that decision trees are always better than neural networks or vice-versa. There are various factors at play, such as the size and structure of your dataset. As a result, you should try many different algorithms for your problem, while using a hold-out "test set" of data to decide performance and select the winning algorithm.
An Empirical Study on Clustering Pretrained Embeddings: Is Deep Strictly Better?
Scott, Tyler R., Liu, Ting, Mozer, Michael C., Gallagher, Andrew C.
Recent research in clustering face embeddings has found that unsupervised, shallow, heuristic-based methods -- including $k$-means and hierarchical agglomerative clustering -- underperform supervised, deep, inductive methods. While the reported improvements are indeed impressive, experiments are mostly limited to face datasets, where the clustered embeddings are highly discriminative or well-separated by class (Recall@1 above 90% and often nearing ceiling), and the experimental methodology seemingly favors the deep methods. We conduct a large-scale empirical study of 17 clustering methods across three datasets and obtain several robust findings. Notably, deep methods are surprisingly fragile for embeddings with more uncertainty, where they match or even perform worse than shallow, heuristic-based methods. When embeddings are highly discriminative, deep methods do outperform the baselines, consistent with past results, but the margin between methods is much smaller than previously reported. We believe our benchmarks broaden the scope of supervised clustering methods beyond the face domain and can serve as a foundation on which these methods could be improved. To enable reproducibility, we include all necessary details in the appendices, and plan to release the code.
Spatiotemporal k-means
Dorabiala, Olga, Webster, Jennifer, Kutz, Nathan, Aravkin, Aleksandr
The widespread use of sensor and data acquisition technologies, including IOT, GPS, RFID, LIDAR, satellite, and cellular networks allows for, among other applications, the continuous monitoring of the positions of moving objects of interest. These technologies create rich spatiotemporal data that is found across many scientific and real-world domains including ecologists' studies of collective animal behavior [13], the surveillance of large groups of people for suspicious activity [17], and traffic management [12]. Often, the data collected is large and unlabeled, motivating the development of unsupervised learning methods that can efficiently extract information about object behavior with no human supervision. In this study, we propose a method of spatiotemporal k-means (STKM) clustering that is able to analyze the multi-scale relationships within spatiotemporal data. Clustering is a major unsupervised data mining tool used to gain insight from unlabeled data by grouping objects based on some similarity measure [6, 11]. The most common methods for unsupervised clustering include k-means, Gaussian mixture models, and hierarchical clustering [18], all of which are workhorse algorithms for the data science industry.
How Hierarchical Clustering works part1
Abstract: The time needed to apply a hierarchical clustering algorithm is most often dominated by the number of computations of a pairwise dissimilarity measure. Such a constraint, for larger data sets, puts at a disadvantage the use of all the classical linkage criteria but the single linkage one. However, it is known that the single linkage clustering algorithm is very sensitive to outliers, produces highly skewed dendrograms, and therefore usually does not reflect the true underlying data structure -- unless the clusters are well-separated. To overcome its limitations, we propose a new hierarchical clustering linkage criterion called Genie. Namely, our algorithm links two clusters in such a way that a chosen economic inequity measure (e.g., the Gini- or Bonferroni-index) of the cluster sizes does not drastically increase above a given threshold. The presented benchmarks indicate a high practical usefulness of the introduced method: it most often outperforms the Ward or average linkage in terms of the clustering quality while retaining the single linkage's speed.