摘要:
A system that incorporates an interactive graphical user interface for visualizing clusters (categories) and segments (summarized clusters) of data. Specifically, the system automatically categorizes incoming case data into clusters, summarizes those clusters into segments, determines similarity measures for the segments, scores the selected segments through the similarity measures, and then forms and visually depicts hierarchical organizations of those selected clusters. The system also automatically and dynamically reduces, as necessary, a depth of the hierarchical organization, through elimination of unnecessary hierarchical levels and inter-nodal links, based on similarity measures of segments or segment groups. Attribute/value data that tends to meaningfully characterize each segment is also scored, rank ordered based on normalized scores, and then graphically displayed. The system permits a user to browse through the hierarchy, and, to readily comprehend segment inter-relationships, selectively expand and contract the displayed hierarchy, as desired, as well as to compare two selected segments or segment groups together and graphically display the results of that comparison. An alternative discriminant-based cluster scoring technique is also presented.
摘要:
A system that incorporates an interactive graphical user interface for visualizing clusters (categories) and segments (summarized clusters) of data. Specifically, the system automatically categorizes incoming case data into clusters, summarizes those clusters into segments, determines similarity measures for the segments, scores the selected segments through the similarity measures, and then forms and visually depicts hierarchical organizations of those selected clusters. The system also automatically and dynamically reduces, as necessary, a depth of the hierarchical organization, through elimination of unnecessary hierarchical levels and inter-nodal links, based on similarity measures of segments or segment groups. Attribute/value data that tends to meaningfully characterize each segment is also scored, rank ordered based on normalized scores, and then graphically displayed. The system permits a user to browse through the hierarchy, and, to readily comprehend segment inter-relationships, selectively expand and contract the displayed hierarchy, as desired, as well as to compare two selected segments or segment groups together and graphically display the results of that comparison. An alternative discriminant-based cluster scoring technique is also presented.
摘要:
In one exemplary embodiment the invention provides a data mining system for use in finding cluster of data items in a database or any other data storage medium. A portion of the data in the database is read from a storage medium and brought into a rapid access memory buffer whose size is determined by the user or operating system depending on available memory resources. Data contained in the data buffer is used to update the original model data distributions in each of the K clusters in a clustering model. Some of the data belonging to a cluster is summarized or compressed and stored as a reduced form of the data representing sufficient statistics of the data. More data is accessed from the database and the models are updated. An updated set of parameters for the clusters is determined from the summarized data (sufficient statistics) and the newly acquired data. Stopping criteria are evaluated to determine if further data should be accessed from the database. Each time the data is read from the database, a holdout set of data is used to evaluate the model then current as well as other possible cluster models chosen from a candidate set of cluster models. The evaluation of the holdout data set allows a cluster model with a different cluster number K′ to be chosen if that model more accurately models the data based upon the evaluation of the holdout set.
摘要:
Iterative validation for efficiently determining error-tolerant frequent itemsets is disclosed. A description of the application of error-tolerant frequent itemsets to efficiently determining clusters as well as initializing clustering algorithms are also given. In one embodiment, a method determines a sample set of error-tolerant frequent itemsets (ETF's) within a uniform random sample of data within a database. This sample set of ETF's is independently validated, so that, for example, spurious ETF's and spurious dimensions within the ETF's can be removed. The validated sample set of ETF's, is added to the set of ETF's for the database. This process is repeated with additional uniform samples that are mutually exclusive from prior uniform samples, to continue building the database's set of ETF's, until no new sample sets can be found. The method is significantly more efficient than disk-based methods in the prior art, and the data clusters found are often not discovered by traditional clustering algorithm in the prior art.
摘要:
One exemplary embodiment of a scalable clustering algorithm accesses a database of records having attributes or data fields of both enumerated discrete and ordered values and brings a portion of the data records into a rapid access memory. A cluster model for the data includes a table of probabilities for the enumerated, discrete data fields of the data records. The cluster model for data fields that are ordered comprises a mean and spread of the cluster. The cluster model is updated from the database records brought into the rapid access memory. At least some of the database records in the rapid access memory are summarized and stored within the rapid access memory. A criteria is then evaluated to determine if further data should be accessed from the database to further cluster data records in the database. Based on the evaluating step, additional database records in the database are accessed and brought into the rapid access memory for further updating of the cluster model.
摘要:
A data mining system for use in finding clusters of data items in a database or any other data storage medium. The clusters are used in categorizing the data in the database into K different clusters within each of M models. An initial set of estimates (or guesses) of the parameters of each model to be explored (e.g. centriods in K-means), of each cluster are provided from some source. Then a portion of the data in the database is read from a storage medium and brought into a rapid access memory buffer whose size is determined by the user or operating system depending on available memory resources. Data contained in the data buffer is used to update the original guesses at the parameters of the model in each of the K clusters over all M models. Some of the data belonging to a cluster is summarized or compressed and stored as a reduced form of the data representing sufficient statistics of the data. More data is accessed from the database and the models are updated. An updated set of parameters for the clusters is determined from the summarized data (sufficient statistics) and the newly acquired data. Stopping criteria are evaluated to determine if further data should be accessed from the database. If further data is needed to characterize the clusters, more data is gathered from the database and used in combination with already compressed data until the stopping criteria has been met.
摘要:
A generalization of frequent item sets to error-tolerant frequent item sets (ETF) is disclosed, together with its application in data clustering using error-tolerant frequent item sets to either build clusters or as an initialization technique for standard clustering algorithms. Efficient feasible computational algorithms for computing ETF's from very large databases is presented. In one embodiment, a method determines a plurality of weak ETF's, which are strongly tolerant of errors, and determines a plurality of strong ETF's therefrom, which are less tolerant of errors. The resulting clusters can be used as an initial model for a standard clustering approach, or may themselves be used as the end clusters. In one embodiment, the data covered by the strong clusters is removed from the data, and the process is repeated, until no more weak clusters can be found. Te invention includes methods for constructing ETF's from more general data types: data sets that include categorical discrete, continuous, and binary attributes.
摘要:
In one exemplary embodiment the invention provides a data mining system for use in finding clusters of data items in a database or any other data storage medium. Before the data evaluation begins a choice is made of the number M of models to be explored, and the number of clusters (K) of clusters within each of the M models. The clusters are used in categorizing the data in the database into K different clusters within each model. An initial set of estimates for a data distribution of each model to be explored is provided. Then a portion of the data in the database is read from a storage medium and brought into a rapid access memory buffer whose size is determined by the user or operating system depending on available memory resources. Data contained in the data buffer is used to update the original model data distributions in each of the K clusters over all M models. Some of the data belonging to a cluster is summarized or compressed and stored as a reduced form of the data representing sufficient statistics of the data. More data is accessed from the database and the models are updated. An updated set of parameters for the clusters is determined from the summarized data (sufficient statistics) and the newly acquired data. Stopping criteria are evaluated to determine if further data should be accessed from the database.
摘要:
As an optimization problem, clustering data (unsupervised learning) is known to be a difficult problem. Most practical approaches use a heuristic, typically gradient-descent, algorithm to search for a solution in the huge space of possible solutions. Such methods are by definition sensitive to starting points. It has been well-known that clustering algorithms are extremely sensitive to initial conditions. Most methods for guessing an initial solution simply make random guesses. In this paper we present a method that takes an initial condition and efficiently produces a refined starting condition. The method is applicable to a wide class of clustering algorithms for discrete and continuous data. In this paper we demonstrate how this method is applied to the popular K-means clustering algorithm and show that refined initial starting points indeed lead to improved solutions. The technique can be used as an initializer for other clustering solutions. The method is based on an efficient technique for estimating the modes of a distribution and runs in time guaranteed to be less than overall clustering time for large data sets. The method is also scalable and hence can be efficiently used on huge databases to refine starting points for scalable clustering algorithms in data mining applications.
摘要:
A computer data processing system. A method for clustering data in a database comprising providing a database having a number of data records having both discrete and continuous attributes. Grouping together data records from the database which have specified discrete attribute configurations. Clustering data records having the same or similar specified discrete attribute configuration based on the continuous attributes to produce an intermediate set of data clusters. And, merging together clusters from the intermediate set of data clusters to produce a clustering model.