International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 56

ISSN 2229-5518

Presentation of Hybrid Genetic Algorithm for

Effective Feature Selection

Hamideh Ganji Arjenaki, Mohammad Nadimi Shahraki, Nasim Noorafza

Abstract—Many sciences encounter large volume of information with advancement of data collection and storage capabilities in recent decades. Nowadays, substrate data creates new challenges in data analysis while traditional statistical methods are not responsible for these data analysis due to the increase in number of observations and variables. Feature selection was used for solving this problem. In selection feature, the best combination of features is surveyed and it requires time and high processing. This paper tried to use the combination of genetic algorithm and artificial neural network for solving this problem. A single-layer Perceptron is topology of artificial neural network. The results of the study showed that the best combination from set of features was found in the shortest time and more optimal way.

Index Terms— Feature selection, Genetic algorithm, Artificial neural networks.

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esearchers in different fields such as engineering, astron- omy, biology, and economics face with more and more observations. Traditional statistical methods missed their efficiency because of two reasons. The fist reason is the in- crease in number of observations.The second reason which is of utmost importance, is the increase of variables in one ob- servation. Therefore, new data analyses face with serious chal- lenges [1]. For example, the varied experiments should be per- formed on the patients in order to diagnose disease in medical field. This work is in company with cost and side effects on the patients. At last, large volume of information is available that all of them are not used in diagnosing. There is a high probability that they cannot be used for disease diagnosis [2],
[3], [4].
Effective feature selection not only reduces cost and time of
disease diagnosis, but also achieves the best combination. The
present study consists of the following sections: reduction of
data dimensions, genetic algorithm, and advantages of using
genetic algorithm in feature selection, results, and future


Substrate data have many dimensions and create many com- putational challenges although they generate opportunities. One of the problems in data with numerous dimensions is that all features of data for finding knowledge hided in data are not vital. So, reduction of data dimensions is still one of im- portant topic in many fields. Data dimension reduction meth- ods are divided for two
groups: methods based on feature extraction and methods


Faculty of Computer Engineering, Najafabad branch, Islamic Azad Univer- sity, Najafabad , Iran .E-mail:.

Faculty of Computer Engineering, Najafabad branch, Islamic Azad Univer- sity, Najafabad , Iran. E-mail:

Faculty of Computer Engineering, Najafabad branch, Islamic Azad Univer- sity, Najafabad , Iran. E-mail:

based on feature selection [1], [5]. The aim of this paper is to present an effective method for feature selection.
Feature selection is finding a subset from features with the minimum numbers. So, it should include sufficient infor- mation. The main purpose of all algorithms and feature selec- tion method is this subset.
Fakunaga and Narewenda (1977) presented a definition and they brought up selection of a subset with M elements from among N features, while M is smaller than N (M < N) and value of criterion function for subset should be more optimal than other subsets. Various feature selection methods try to find the best subset between 2 subsets of candidate. In all of these methods, the subset is selected as an answer that can optimize value of criterion function. Each method tries to
select the best features, however, with the respect the breadth
of possible answer and the increase of sets of answer exponen-
tially with N, finding optimal answer is difficult and N medi-
um and large is very costly [6].
Feature selection process includes four steps: production sub-
set, evaluation subset, stopping criterion, and validation re-
sults [7].


John Holland from Michigan University proposed the use of genetic algorithm in optimizing engineering. The main point of this algorithm is transmission of inherited attributes by genes. Set of features are transferred in human beings to next population by their chromosomes. Each gene is representative of one attribute in these chromosomes.
Two events were happened for chromosomes simultaneously. The first event is mutation and another one is crossover [8], [9].


As mentioned before, the experts try to reduce the data di- mension in different fields and select effective features be- cause of the increase in the number of features and dimen- sions. There are applied researches in medical field about this issue. Some of these studies are investigated on feature selec-

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International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 57

ISSN 2229-5518

tion and some other investigated on feature extraction.
Arsalan and Turkoglu (2002) presented one system for di-
agnosing heart valve disease by using data diming and its
techniques. In this system, the interpretation of Doppler sig-
nals of the heart was carried out on the basis of pattern recog-
nition. Disease diagnosis was done based on the feature ex-
traction from waveform and classification of features was done with neural network of propagation [10].
Damtew (2011) used feature selection for predicting of heart disease.In this method ,the preprocessing was done on the data and then, features were selected by best first search method. After that, they were classified by J48 method in or- der to determine the percentage of accuracy in predicting [11]. In this search method, all subsets were searched by feature selection method and the answer did not far from algorithm. On the one hand, in this method was checked all subsets. So, That can be time-consuming especially when the number of features are large.
Lee et al. (2008) used solution of feature extraction and clas- sification for predicting heart disease. Greedy hill climbing was used for feature extraction and CPAR and SVM methods was used for classification [12].
R. Alizadeh et al. was done some researches on three ves- sels of LCX, LAD, and RCA for determining cardiovascular. The use of feature selection method and classification for evaluating selected features was the solution of this study. Also, the gain ratio was used for feature selection. The effec- tive features were recognized based on its value. C4.5 Classifi- er was used based on obtained features [4].
H. Yan et al. searched about use of feature selection for di- agnosing of heart. The aim of this paper was to select effective features. Algorithm genetic was used for diagnosing of heart disease [13].


First, a certain number of inputs (x1, x2, …, xn) from sam- ple space of X are selected. Then, they are put in a vector x=(x1, x2, ….) that xn is called chromosome. The group of chromosomes is called population. Each chromosome grows in each period and develops based on specific rules of biologi- cal evolution.
There is a fitness function for each chromosome xi which is called f (Xi). The stronger elements or chromosomes value of optimization is competence of chromosomes. The stronger elements or chromosomes. They have more chance to survive in other periods and they can be reproduced.
Weak elements are ruined. In fact, genetic algorithm retains inputs that are near to more optimal answer and abandon oth- ers. Birthday is another important step in this algorithm and accrues in this period. The contents of two chromosomes are combined with together in process of generation in order to generate two new chromosomes. This rule allows two the best parents combine with together for generating better offspring. Furthermore, a series of chromosomes may be mutated in each period.
In this solution in order to create new generation, firstly, the new generation are formed by roulette wheel selection,
crossover and mutation operation. In crossover operator use one point, two point and three points.
Fitness function is used for evaluating new generation which the amount of competency is determined in that chro- mosome. In this solution, the artificial neural networks with the topology single layer of Perceptron is used for fitness func- tion. Therefore, the primary data set are filtered with respect to set of generated feature (chromosomes which are surveyed) and they are classified with artificial neural network. The higher percentage of accuracy shows the better set of features.


Genetic algorithm does not require certain mathematic and it tries to solve optimization problems without paying atten- tion to inner performance. This algorithm is able to solve any limitations (such as linear or nonlinear) which is defined on continuous, discrete or mixed search space.
Performance of this algorithm has been demonstrated ex- perimentally. Structure of genetic algorithm operations makes this algorithm to act more successful in finding optimal an- swers. In traditional methods, the search is done with adjacent points by comparison and move to the points with relative optimization. Genetic algorithm has high flexibility in combi- nation with innovative techniques. So, it can solve the problem effectively [9].
Genetic algorithm can solve different problems by coding in the form of chromosome.Structure of genetic algorithm pre- sents tools for optimizing parameter solution in a specific problem. This is an easy and understandable method that math requirements are very low (or even no). This tool can be simulated easily by mediums [14].
This algorithm is considered an effective tool for the search if there is a little background knowledge about the problem and evaluating quality of selected samples is not available.
Genetic algorithm is a random search model and produces and evaluates set of various features in a short of time. In this algorithm, the number of subsets can be increased in several times with trifle changes. If this method is done with algo- rithms of other selected features, it requires time and high cal- culations.
Genetic algorithm is more common and useful method among other methods for finding suitable feature selection because of two reasons. The first reason is having high power in selecting varied features and the second one is having high speed. Use of genetic algorithm makes a rapid move in space of problem. This algorithm has high capability in problem solving [15]. If feature selection is based on fitness function, the subsets having negative effect are not selected as the final subset. Genetic algorithm has more power in finding answer of problem, especially when space of mode is big.
With selection of fitness function, the subset having higher accuracy of classification and lower cost, has a bigger value of fitness function. The final value of fitness function is consid- ered as a ranking for each generated subset and the subset that acquires higher rank, is selected as the best subset.
Structure of problem and capability of genetic algorithm in suitable modeling is another reason in selection of genetic al- gorithm for problem solving and feature selection.

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In addition to above-mentioned advantages for genetic al- gorithm, previous researches applied this technique for dis- ease diagnosis and achieved good results. This is another rea- son for reliability in using this algorithm [3], [16].
If the answer is among chromosomes that are in lower rank with respect to fitness function, the chromosomes will have chance of selecting by the use roulette wheel operator [17], [18].
The proposed solution can be used in other problems easily and can be taken advantage of its benefits. So, other parame- ters are involved in fitness function with respect to this issue. The way of parameter’s relation with fitness function should be determined. For example, in the problem that the time re- duction is surveyed, whatever the time be shorter, the features are more suitable.
So, the cost parameter is placed in the denominator of fit- ness function.


Researchers should use some techniques for reduction of dimensions in order to analyze them because of large volume of information.
In this way, feature selection methods reduce the effective number features and perform analysis in an effective form. Genetic algorithm is one the more efficient and more applica- ble feature selection methods in this field. It has a lot of ad- vantages in most of fields such as high speed of algorithm, processing of different modes, acting well even with little background knowledge.
In this field, future researches can be done on combination of genetic algorithm with other algorithms such as phase algo- rithms in different issues for effective feature selection.


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