svm

892 Words2 Pages

Generally, feature selection techniques designed with different appraisement criteria, are categorized into two divisions: the filter algorithms (Huang and Tesai, 2009;Kara et al ,2011), and the wrapper algorithms(Liang et al,2011;Nair et al,2010). Gaining no feedback from classifier, the filter algorithms estimate the classification performance by some indirect assessments, such as distance measures that reflect how well the classes separate from each other (Li-Ping et al, 2011).On the contrary, the wrapper algorithms are classifier-dependent. Based on the classification accuracy, the methods evaluate the ‘‘goodness” of the selected feature subset directly that should intuitively yield better performance. Many experimental results reported so far, are in favor of the wrapper methods (Luo and Chen, 2013;Teixeria and Olivieria,2010). In spite of the good performance, the wrapper methods have had restricted employment because of the high computational intricacy involved. In this paper genetic algorithm (GA) as a filter technique is employed in terms of feature selection purpose to result in a better diagnosis of the stock’s trends.

3.3. Support vector machine (SVM)
Support vector machine (SVM), which is based on structural risk minimizations concepts and statistical learning theory, was developed firstly by Vapnik (1995).Two remarkable applications of SVM is pattern recognition (classification) as well as regression estimation (approximation of functions).These applications make SVM as a popular method among researchers to implement it to solve problems such as nonlinear modeling, time series forecasting and etc. In this article, it’s classification algorithm has been applied to forecast the price of each stock in certain time peri...

... middle of paper ...

...diction. When using the RBF kernel, there are two notable parameters C, γis needed to be carefully chose in the SVM algorithm.In this article, the parameters of C, γ are optimized by cross-validation (Lin et al, 2008) and grid search. The training set is divided into six folds. One fold was taken as the validation set and the others applied for training. The grid point with the highest precision of predicting is used as the value of the two parameters. Rapid Miner software SVM’’s operator was used for conduction of SVM algorithm. The original data (selected technical indicators resulted by GA) are scaled into the range of (0, 1). The purpose of linear scaling is to autonomously normalize each feature quantity to the specified range. It guarantees that the larger value input attributes do not overwhelm smaller value inputs; hence helps to decrease prediction errors.

Open Document