# similarity and distance measures in clustering ppt

Points, Spaces, and Distances: The dataset for clustering is a collection of points, where objects belongs to some space. For example, consider the following data. In KNN we calculate the distance between points to find the nearest neighbor, and in K-Means we find the distance between points to group data points into clusters based on similarity. INTRODUCTION: For algorithms like the k-nearest neighbor and k-means, it is essential to measure the distance between the data points.. Clustering is a useful technique that organizes a large quantity of unordered text documents into a small number of meaningful and coherent cluster. Common Distance Measures Distance measure will determine how the similarity of two elements is calculated and it will influence the shape of the clusters. •Basic algorithm: Documents with similar sets of words may be about the same topic. Chapter 3 Similarity Measures Written by Kevin E. Heinrich Presented by Zhao Xinyou [email_address] 2007.6.7 Some materials (Examples) are taken from Website. a space is just a universal set of points, from which the points in the dataset are drawn. If meaningful clusters are the goal, then the resulting clusters should capture the “natural” Introduction to Clustering Techniques. 3 5 Minkowski distances • One group of popular distance measures for interval-scaled variables are Minkowski distances where i = (xi1, xi2, …, xip) and j = (xj1, xj2, …, xjp) are two p-dimensional data objects (e.g. Similarity Measures for Binary Data Similarity measures between objects that contain only binary attributes are called similarity coefficients, and typically have values between 0 and 1. A wide variety of distance functions and similarity measures have been used for clustering, such as squared Euclidean distance, and cosine similarity. Here, the contribution of Cost 2 and Cost 3 is insignificant compared to Cost 1 so far the Euclidean distance … A value of 1 indicates that the two objects are completely similar, while a value of 0 indicates that the objects are not at all similar. The Euclidean distance (also called 2-norm distance) is given by: 2. similarity measure 1. Clustering (HAC) •Assumes a similarity function for determining the similarity of two clusters. Chapter 3 Similarity Measures Data Mining Technology 2. A major problem when using the similarity (or dissimilarity) measures (such as Euclidean distance) is that the large values frequently swamp the small ones. •Starts with all instances in a separate cluster and then repeatedly joins the two clusters that are most similar until there is only one cluster. The Manhattan distance (also called taxicab norm or 1-norm) is given by: 3.The maximum norm is given by: 4. They include: 1. Introduction 1.1. The requirements for a function on pairs of points to be a distance measure are that: Scope of This Paper Cluster analysis divides data into meaningful or useful groups (clusters). 4 1. 10 Example : Protein Sequences Objects are sequences of {C,A,T,G}. Clustering Distance Measures Hierarchical Clustering k-Means Algorithms. vectors of gene expression data), and q is a positive integer q q p p q q j x i x j •The history of merging forms a binary tree or hierarchy. Introduction to Hierarchical Clustering Analysis Dinh Dong Luong Introduction Data clustering concerns how to group a set of objects based on their similarity of ... – A free PowerPoint PPT presentation (displayed as a Flash slide show) on PowerShow.com - id: 71f70a-MTNhM I.e. For clustering, such as squared Euclidean distance, and cosine similarity, and Distances: the for. That: similarity measure 1 will determine how the similarity of two elements calculated... 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