an:05968908
Zbl 1225.68157
Chang, Kai-Wei; Hsieh, Cho-Jui; Lin, Chih-Jen
Coordinate descent method for large-scale L2-loss linear support vector machines
EN
J. Mach. Learn. Res. 9, 1369-1398 (2008).
1532-4435 1533-7928
2008
j
68T05 62H30
linear support vector machines; document classification; coordinate descent
Summary: Linear support vector machines (SVM) are useful for classifying large-scale sparse data. Problems with sparse features are common in applications such as document classification and natural language processing. In this paper, we propose a novel coordinate descent algorithm for training linear SVM with the L2-loss function. At each step, the proposed method minimizes a one-variable sub-problem while fixing other variables. The sub-problem is solved by Newton steps with the line search technique. The procedure globally converges at the linear rate. As each sub-problem involves only values of a corresponding feature, the proposed approach is suitable when accessing a feature is more convenient than accessing an instance. Experiments show that our method is more efficient and stable than state of the art methods such as Pegasos and TRON.