This paper proposes an efficient method for clustering large amount of time sequences using dynamic time warping (DTW). This method introduces a "maxDist" constraint to limit the distance between time sequences. Based on this constraint, we developed a new hierarchical clustering algorithm which leverages multi-dimensional indexing to prune unnecessary DTW computations. In addition, in order to reduce the expensive computation cost of DTW, a new constraint-based DTW algorithm is proposed which can stop calculation for cells in the cost matrix once the partial distance is larger than the maxDist constraint. Experiments have been performed on a synthetic data set to evaluate its performance as well as on a real cyber security data set in order to identify groups of entities with common time sequence patterns.

Predictive Coding, also called Text Categorization, has been widely used in legal industry. By leveraging machine learning models such as logistic regression and SVM, the review of documents can be prioritized based on their probability of relevance to the legal case, thus improving review efficiency and cutting cost. In recent years, deep learning models-combined with word embeddings-have shown better performance in predictive coding. However, deep learning models involve many parameters and it is challenging and time-consuming for legal practitioners to select appropriate settings. Based on the experiments on several public legal text datasets, this paper shows the preliminary results about how various key parameter settings impact the performance of Convolutional Neural Networks (CNNs).

Spatial outliers are the spatial objects whose nonspatial attribute values are quite different from those of their spatial neighbors. Identification of spatial outliers is an important task for data mining researchers and geographers. A number of algorithms have been developed to detect spatial anomalies in meteorological images, transportation systems, and contagious disease data. In this paper, we propose a set of graph-based algorithms to identify spatial outliers. Our method first constructs a graph based on k-nearest neighbor relationship in spatial domain, assigns the nonspatial attribute differences as edge weights, and continuously cuts high- weight edges to identify isolated points or regions that are much dissimilar to their neighboring objects. The proposed algorithms have two major advantages compared with the existing spatial outlier detection methods: accurate in detecting point outliers and capable of identifying region outliers. Experiments conducted on the US Housing data demonstrate the effectiveness of our proposed algorithms.

Spatial outliers are the spatial objects with distinct features from their surrounding neighbors. Detection of spatial outliers helps reveal valuable information from large spatial data sets. In many real applications, spatial objects can not be simply abstracted as isolated points. They have different boundary, size, volume, and location. These spatial properties affect the impact of a spatial object on its neighbors and should be taken into consideration. In this paper, we propose two spatial outlier detection methods which integrate the impact of spatial properties to the outlierness measurement. Experimental results on a real data set demonstrate the effectiveness of the proposed algorithms.

Spatial outliers are the spatial objects with distinct features from their surrounding neighbors. Detection of spatial outliers helps reveal important and valuable information from large spatial data sets. In the field of meteorology, for example, spatial outliers can be associated with disastrous natural events such as tornadoes, hurricane, and forest fires. Previous study of spatial outlier mainly focuses on point data. However, in the meteorological data or other applications, spatial outliers are frequently represented in region, i.e., a group of points, with two dimensions or even three dimensions, and the previous point-based approaches may not be appropriate to be used. As region outliers are commonly multi-scale objects, wavelet analysis is an effective tool to study them. In this paper, we propose a wavelet analysis based approach to detect region outliers. We discuss the region outlier detection problem and design a suite of algorithms to effectively discover them. The algorithms were implemented and evaluated with a real-world meteorological data set.

A spatial outlier is a spatially referenced object whose non-spatial attribute values are significantly different from the values of its neighborhood. Identification of spatial outliers can lead to the discovery of unexpected, interesting, and useful spatial patterns for further analysis. One drawback of existing methods is that normal objects tend to be falsely detected as spatial outliers when their neighborhood contains true spatial outliers. We propose a suite of spatial outlier detection algorithms to overcome this disadvantage. We formulate the spatial outlier detection problem in a general way and design algorithms which can accurately detect spatial outliers. In addition, using a real-world census data set, we demonstrate that our approaches can not only avoid detecting false spatial outliers but also find true spatial outliers ignored by existing methods.

A spatial outlier is a spatially referenced object whose non-spatial attribute values are significantly different from the values of its neighborhood. Identification of spatial outliers can lead to the discovery of unexpected, interesting, and useful spatial patterns for further analysis. Previous work in spatial outlier detection focuses on detecting spatial outliers with a single attribute. In the paper, we propose two approaches to discover spatial outliers with multiple attributes. We formulate the multi-attribute spatial outlier detection problem in a general way, provide two effective detection algorithms, and analyze their computation complexity. In addition, using a real-world census data, we demonstrate that our approaches can effectively identify local abnormality in large spatial data sets.