PREPROCESSING THE FEATURE SELECTION ON MINING ALGORITHM - REVIEW

PREPROCESSING THE FEATURE SELECTION ON MINING ALGORITHM - REVIEW G.VENKATESWARAN ASSISTANT PROFESSOR, Department of IT &BCA, NPR ARTS AND SCIENCE COLLEGE, NATHAM, ABSTRACT Filtration is the process by which it can refine the unwanted data from dataset. It is the major process in data mining technique. It makes perfection of the dataset to process a learning algorithm on it. Many algorithms can be very helpful to process the filtered data from metadata. Data from UCI data repository can be procedure of proposed method and evaluate the data from it. This Paper mainly focused on preprocessing the data and evaluates the data. In this feature selection, it can be used evaluate each attributes by filtering based algorithm. It may also used to classify the whole dataset by using clustering and other specifying algorithm. Finally, Preprocessing data can be used to refine the data from whole dataset. KEYWORDS: Filtration; preprocessing; INTRODUCTION Data mining is the exploration and analysis of large quantities of data in order to discover valid, novel, potentially useful and ultimately understandable patterns in data.data mining is the process of extracting information or patterns from large database, data warehouses, XML repository, etc. Also data mining is known as one of the core processes of Knowledge Discovery in Database (KDD).In machine learning and statistics, feature selection also known as attribute selection or variable subset selection. It is the process of selecting a subset of relevant features for model construction. Feature selection techniques are a subset of the more general field of feature extraction. Feature extraction can creates new attributes that obtained as original attributes of the dataset, whereas attributes filtering that returns a relevant set of the attributes. An attribute selection is generally categories into main four categories as Filter, Wrapper, Embedded and Hybrid Method. Wrapper Method A predictive model is used in wrapper method score feature subsets. To train a model each new subset is used, which is tested on a hold-out set. On that hold-out set, counting the number of mistakes made (the error rate of the model) gives the score for that subset. G.VENKATESWARAN 1

Filter Method Instead of the error rate, proxy measure is used in filter method to score a feature subset. This measure is very fast to compute. Filters are less computationally intensive than wrappers, they produce feature set which is not tuned to a specific type of predictive model. Embedded Method Embedded method is a catch-all group of techniques that perform feature selection as part of the model construction process. These approaches are between filters and wrappers in terms of computational complexity. The embedded method incorporate feature selections and are specific to given learning algorithm so it is efficient than other methods. Hybrid Method Filter and wrapper method are combined in Hybrid method. To reduce the search space, filter method is used, that will be considered by subsequent wrapper. These methods mainly focus on combination of filter and wrapper methods in order to achieve best performance with particular learning algorithm with similar time complexity of the filter methods. LITERATURE REVIEW: In paper [1], Data mining has one of the key problems that arise in a great variety of fields, including pattern recognition and machine learning, is the so-called feature selection. It can be defined as finding M relevant features from N original features. Algorithms that perform feature selection can generally be categorized into two classes: Wrappers and Filters. The former consider the feature selection as a preprocessing step and independent of the learning algorithm; for the latter, feature selection is wrapped around the learning algorithm and the result of learning algorithm is used as the evaluation criterion. In general, the characteristics of Filters are low time cost and not better effect, on the contrary, the time cost of Wrappers is high for its calling the learning algorithm to evaluate candidate subset of considered features, but the effect is better to predetermined learning algorithm. In recent years, data has become increasingly larger in both the number of instances and the number of features, when the number of features is very large, the Filters model is usually chosen due to its computation efficiency or apply Filters to reduce the dimensionality of feature set before Wrappers. Generally, the characteristics of problems with high-dimensional feature set are described as Large numbers of features, Many irrelevant features, Many redundant features, Noisy data. In paper [2], the development of feature selection has two major directions. One is the filters [8] and the other is the wrappers [9]. The filters work fast using a simple measurement, but its result is not always satisfactory. On the other hand, the wrappers guarantee good results through examining learning results, but it is very slow when applied to wide feature sets which contain hundreds or even thousands of features. Through the filters are very efficient in selecting features, they are unstable when performing on wide feature sets. This research tries to incorporate the wrappers to deal with this problem. It is not a pure wrapper procedure, but rather a hybrid feature selection model which utilizes both filter and wrapper methods. In these method, two feature sets are first filtered out by F-score and information gain, G.VENKATESWARAN 2

respectively. The feature sets are then combined and further tuned by a wrapper procedure. We take advantages of both the filter and the wrapper. It is not as fast as a pure filter, but it can achieve a better result than a filter does. Most importantly, the computational time and complexity can be reduced in comparison to a pure wrapper. The hybrid mechanism is more feasible in real bioinformatics applications which usually involve a large amount of related features. In the experiments, we applied the proposed hybrid feature selection mechanism to the problems of disordered protein prediction [10] and gene selection of microarray cancer data [11].The effective feature selection is always very helpful. In paper [3], an important challenge in the problem of classification of high-dimensional data is to design a learning algorithm that can construct an accurate classifier that depends on the smallest possible number of attributes. Further, it is often desired that there should be realizable guarantees associated with the future performance of such feature selection approaches See, for instance, a recent algorithm proposed by [12] involving the identification of a gene subset based on importance ranking and, subsequently, combinations of genes for classification. The traditional methods used for classifying high dimensional data are often characterized as either filters (e.g., [12], [13]) or wrappers (e.g., [14]), depending on whether the attribute selection is performed independent of, or in conjunction with, the base learning algorithm. The proposed approaches are a step toward more general learning strategies that combine feature selection with the classification algorithm and have tight realizable guarantees. In paper [4], With the aim of choosing a subset of good features with respect to the target concepts, feature subset selection is an effective way for reducing dimensionality, removing irrelevant data, increasing learning accuracy, and improving result comprehensibility [15], [16]. Many feature subset selection methods have been proposed and studied for machine learning applications. They are divided into four broad categories, Embedded, Wrapper, Filter, and Hybrid approaches. The embedded methods incorporate feature selection as a part of the training process and are usually specific to given learning algorithms, and therefore may be more efficient than the other three categories [17]. The wrapper methods use the predictive accuracy of a predetermined learning algorithm to determine the goodness of the selected subsets, the accuracy of the learning algorithms is usually high. However, the generality of the selected features is limited and the computational complexity is large. The filter methods are independent of learning algorithms, with good generality. The hybrid methods are a combination of filter and wrapper methods [18-22] by using a filter method to reduce search space that will be considered by the subsequent wrapper. They mainly focus on combining filter and wrapper methods to achieve the best possible performance with a particular learning algorithm with similar time complexity of the filter methods. The wrapper methods are computationally expensive. The filter methods, in addition to their generality, are usually a good choice when the number of features is very large. Thus, we will focus on the filter method in this paper. With respect to the filter feature selection methods, the application of cluster analysis has been demonstrated to be more effective than traditional feature selection algorithms. In paper [5], Feature selection is the process of detecting the relevant features and discarding the irrelevant ones. A correct selection of the features can lead to an improvement of the inductive learner, G.VENKATESWARAN 3

either in terms of learning speed, generalization capacity or simplicity of the induced model. There are some other benefits associated with a smaller number of features: a reduced measurement cost and hopefully a better understanding of the domain. There are several situations that can hinder the process of feature selection, such as the presence of irrelevant and redundant features, noise in the data or interaction between attributes. In the presence of hundreds or thousands of features, such as DNA microarray analysis, researchers notice [23, 24] that is common that a large number of features is not informative because they are either irrelevant or redundant with respect to the class concept. Moreover, when the number of features is high but the number of samples is small, machine learning gets particularly difficult, since the search space will be sparsely populated and the model will not be able to distinguish correctly the relevant data and the noise [25]. There exist two major approaches in feature selection: individual evaluation and subsetevaluation. Individual evaluation is also known as feature ranking [26] and assesses individual features by assigning them weights according to their degrees of relevance. On the other hand, subset evaluation produces candidate feature subsets based on a certain search strategy. Besides this classification, feature selection methods can also be divided into three models: filters, wrappers and embedded methods [27].With such a vast body of feature selection methods, the need arises to find out some criteria that enable users to adequately decide which algorithm to use (or not) in certain situations. This work reviews several feature selection methods in the literature and checks their performance in an artificial controlled experimental scenario, contrasting the ability of the algorithms to select the relevant features and to discard the irrelevant ones without permitting noise or redundancy to obstruct this process. In paper [6], a supervised learning algorithm receives a set of labeled training examples, each with a feature vector and a class. The presence of irrelevant or redundant features in the feature set can often hurt the accuracy of the induced classifier [28]. Feature selection, the process of selecting a feature subset from the training examples and ignoring features not in this set during induction and classification, is an effective way to improve the performance and decrease the training time of a supervised learning algorithm. Feature selection typically improves classifier performance when the training set is small without significantly degrading performance on large training sets [29]. Feature selection is sometimes essential to the success of a learning algorithm.feature selection can reduce the number of features to the extent that such an algorithm can be applied.algorithms used for selecting features prior to concept induction fall into two categories. Wrapper methods wrap the feature selection around the induction algorithm to be used, using cross-validation to predict the benefits of adding or removing a feature from the feature subset used. Filter methods are general preprocessing algorithms that do not rely on any knowledge of the algorithm to be used. There are strong arguments in favor of both methods. This paper presents a careful analysis of arguments for both methods. It also introduces a new method of feature selection that is based on the concept of boosting from computational learning theory and combines the advantages of filter and wrapper methods. Like filters, it is very fast and general, while at the same time using knowledge of the learning algorithm to inform the search and provide a natural stopping criterion. We present empirical results using two different wrappers and three variants of our algorithm. In paper [7], Feature subset selection (FSS) is one of the techniques to preprocess the data before we perform any data mining tasks, e.g., classification and clustering. FSS is to identify a subset of G.VENKATESWARAN 4

original features/variables [30] from a given data set while removing irrelevant and/or redundant features [31]. The objectives of FSS are to improve the prediction performance of the predictors, to provide faster and more cost-effective predictors, and to provide a better understanding of the underlying process that generated the data. ANALYSIS: REFERENCE ID PROBLEM DATASET DATA FEATURE SELECTION STATUS 1.Efficient feature selection for highdimensional data using two-level filters Feature subset selection contain high correlated to each other. More irrelevant and redundancy. While using genetic time expense is high. UCI dataset Ionosphere Sonar Spectf Multi-feature Using ReliefF& KNNC to remove irrelevant and redundancy data. ALGORITHM K-Nearest Neighbors cluster algorithm 2.Hybrid selection by combining filters and wrappers Feature subset selection has not accurate and fast. Disordered protein dataset and Microarray dataset. AML and ALL Lung cancer Using three step procedure such as preliminary screening, combination and fine tuning the feature should accurate and fast. Filters Vs Wrappers Hybrid Feature selection 3.Feature selection with conjunctions of decisions stumps and learning from microarray data Learning from high-dimensional data of DNA microarray Microarray dataset Colon Leukemia B_MD and C_MD Lung BreastER Celliac disease Colon epithelial biopsies multiple mylenoma and bone lesion By using three learning algorithm, the microarray dataset process with highdimensional data. An Occam s Razor Learning Algorithm A PAC-Bayes Learning Algorithm G.VENKATESWARAN 5

4. A fast-clustering based feature subset selection algorithm for high-dimensional data 5. A review of feature selection methods on synthetic data 6.Filters,Wrappers and a boosting based hybrid for feature selection Irrelevant and redundant data. Some Irrelevant can be removed but redundant data remains in it. Irrelevant, redundant and noisy in the data Both Filter and Wrapper method has some 35 Bench Marks dataset Artificial dataset Multi-class dataset Chess mfeat-fourier coil2000 elephant arrhythmia fqs-nowe colon fbis.wc AR10P PIE10P oh0.wc oh10.wc B-cell1, cell2 cell3, base-hock TOX-171 tr12.wc tr23.wc tr11.wc embryonal-tumours leukemia1 leukemia2 tr21.wc wap.wc PIX10P ORL10P CLL-SUB-111 ohscal.wc la2s.wc la1s.wc GCM SMK-CAN-187 new3s.wc GLA-BRA-180 Corral Corral-100 XOR-100 Parity3+3 Led-25 Led-100 Monk3 SD1* SD2* SD3* Madelon Vote Chess Mushroom DNA Using FAST algorithm and t clusters technique, the irrelevant and redundant data can be removed. Using filters, embedded and wrappers methods used to filters it and ranking the data by ranker method. Using BBHFS(hybrid algorithm), it can merge both methods Fast algorithm Filters method Embedded method Wrappers method Hybrid algorithm Naive Bayes (NB) ID3 with χ2 G.VENKATESWARAN 6

7. Feature subset selection and ranking for multi-variate time series drawbacks to retrieve the significant data from large dataset. Feature selection cannot be specified with ranking and time to get the data from it. 1.HumanGait dataset 2.Brain Computer interface (BCI) data set at the Max Planck Institute (MPI) 3.Brain and Behavior Correlates of Arm Rehabilitation (BCAR) kinematics data set Lymphography Ads - to getting the relevant data. Using many method and algorithm it can specified the data with rank and also calculate the time of the data. pruning (ID3) k- Nearest Neighbors (knn). PC and DCPC CLeVer-Rank. CLeVer Cluster CLeVer-Hybrid CONCLUSION: This literature paper provides distinct types of existing feature selection techniques. Feature selection is one of the important process in data mining which can be used to reduce the irrelevant data and discover the significant data from the dataset. This data mining techniques can help to improve the classifier accurate. It ma y also process in other applications such as medical field etc.. The study of distinct techniques of data mining can concluded that there is a novel method for handling insignificant feature in high dimensional datasets. REFERENCES 1) Ferreira and M. Figueiredo, Efficient feature selection filtersfor high-dimensional data, Pattern Recognit. Lett., vol. 33, no. 13,pp. 1794 1804, 2012. 2) H.-H. Hsu, C.-W. Hsieh, and M.-D. Lu, Hybrid feature selectionby combining filters and wrappers, Expert Syst. Appl., vol. 38,no. 7, pp. 8144 8150, 2011. 3) M. Shah, M. Marchand, and J. Corbeil, Feature selection withconjunctions of decision stumps and learning from microarraydata, IEEE Trans. Pattern Anal. Mach. Intell., vol. 34, no. 1,pp. 174 186, Jan. 2012. 4) Qinbao Song, Jingjie Ni and Guangtao Wang A Fast Clustering-Based Feature SubsetSelection Algorithm for High Dimensional Data IEEE transactions on knowledge and data engineering VOL:25 NO:1 YEAR 2013 5) VerónicaBolón-Canedo Noelia Sánchez-MaroñoAmparo Alonso-Betanzos A review of feature selection methods on synthetic data KnowlInfSyst (2013) 34:483 519 6) S. Das, Filters, wrappers and a boosting-based hybrid for featureselection, in Proc. 18th Int. Conf. Mach. Learn., 2001, pp. 74 81. 7) Hyunjin Yoon, Kiyoung Yang, and Cyrus Shahabi, Feature subset selection and ranking G.VENKATESWARAN 7

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