Search

Network embedding is a fundamental part of many network analysis tasks, including node classification and link prediction. The existing random walk-based embedding methods aim to learn node embedding that preserves information on either node proximity or structural similarity. However, the information on both role and community is important to network nodes. To address the shortcomings of the existing methods, this paper proposes a novel method for network embedding called the RARE, which can be used for the analysis of different types of networks and even disconnected networks. The proposed method uses the role and community information of nodes to preserve both node proximity and structural similarity in the learned node embeddings. The walks generated through the role-aware random walk can capture the role and community information of nodes. The obtained walks are input to the Skip-gram model to learn the final embedding of nodes. In addition, the RARE is extended to the CRARE that adds the sampling of high-order community members to the customized random walk so that the node's representation can preserve more structural information of the network. The performances of the proposed methods are evaluated on multi-class node classification, link prediction, and network visualization tasks. Experimental results on different domain datasets indicate that the proposed methods outperform the baseline methods. The proposed methods can be further accelerated using parallelization in the random walk generation process. The source code: https://github.com/HeguiZhang/RARE. [ABSTRACT FROM AUTHOR]

As each imbalanced classification problem comes with its own set of challenges, the measure used to evaluate classifiers must be individually selected. To help researchers make this decision in an informed manner, experimental and theoretical investigations compare general properties of measures. However, existing studies do not analyze changes in measure behavior imposed by different imbalance ratios. Moreover, several characteristics of imbalanced data streams, such as the effect of dynamically changing class proportions, have not been thoroughly investigated from the perspective of different metrics. In this paper, we study measure dynamics by analyzing changes of measure values, distributions, and gradients with diverging class proportions. For this purpose, we visualize measure probability mass functions and gradients. In addition, we put forward a histogram-based normalization method that provides a unified, probabilistic interpretation of any measure over data sets with different class distributions. The results of analyzing eight popular classification measures show that the effect class proportions have on each measure is different and should be taken into account when evaluating classifiers. Apart from highlighting imbalance-related properties of each measure, our study shows a direct connection between class ratio changes and certain types of concept drift, which could be influential in designing new types of classifiers and drift detectors for imbalanced data streams. [ABSTRACT FROM AUTHOR]