Feature Selection for Multi-label Learning: A Systematic Literature Review and Some Experimental Evaluations

Many real-world data have multiple class labels known as multi-label data, where the labels are correlated with each other, and as such, they are not independent. Since these data are usually high-dimensional, and the current multi-label feature selection methods have not been precise enough, then a new feature selection method is necessary. In this paper, for the first time, we have modeled the problem of multi-label feature selection to a bipartite graph matching process. The proposed method constructs a bipartite graph of features (as the left vertices) and labels (as the right vertices), called Feature-Label Graph (FLG), where each feature is connected to the set of labels, where the weight of the edge between each feature and label is equal to their correlation. Then, the Hungarian algorithm estimates the best matching in FLG. The selected features in each matching are sorted by weighted correlation distance and added to the ranking vector. To select the discriminative features, the proposed method considers both the redundancy of features and the relevancy of each feature to the class labels. The results indicate the superiority of the proposed method against the other methods in classification measures.

Feature selection based on label distribution and fuzzy mutual information

Existing feature selection methods mainly target single-label learning and multi-label learning, and only a few algorithms are optimized for label distribution learning. In label distribution learning, the associated labels of each sample have different levels of importance. Therefore, multi-label feature selection algorithms cannot be directly applied to label distribution learning. Discretizing label distribution data into multi-label data will cause part of the supervision information to be lost. In most practical applications of label distribution learning, the feature space is undefined, and the features are in the form of flow features. To solve this problem, this paper applies fuzzy rough set theory and applies the flow feature framework to propose a dynamic label distribution feature selection algorithm that handles flow features. Experimental results show that the proposed method is more effective than six state-of-the-art feature selection algorithms on 12 datasets with respect to six representative evaluation metrics.

A label-specific multi-label feature selection algorithm based on the Pareto dominance concept

In a conventional supervised learning paradigm, each data instance is associated with one single class label. Multilabel learning differs in the way that data instances may belong to multiple concepts simultaneously, which naturally appear in a variety of high impact domains, ranging from bioinformatics and information retrieval to multimedia analysis. It targets leveraging the multiple label information of data instances to build a predictive learning model that can classify unlabeled instances into one or multiple predefined target classes. In multilabel learning, even though each instance is associated with a rich set of class labels, the label information could be noisy and incomplete as the labeling process is both time consuming and labor expensive, leading to potential missing annotations or even erroneous annotations. The existence of noisy and missing labels could negatively affect the performance of underlying learning algorithms. More often than not, multilabeled data often has noisy, irrelevant, and redundant features of high dimensionality. The existence of these uninformative features may also deteriorate the predictive power of the learning model due to the curse of dimensionality. Feature selection, as an effective dimensionality reduction technique, has shown to be powerful in preparing high-dimensional data for numerous data mining and machine-learning tasks. However, a vast majority of existing multilabel feature selection algorithms either boil down to solving multiple single-labeled feature selection problems or directly make use of the imperfect labels to guide the selection of representative features. As a result, they may not be able to obtain discriminative features shared across multiple labels. In this article, to bridge the gap between a rich source of multilabel information and its blemish in practical usage, we propose a novel noise-resilient multilabel informed feature selection framework (MIFS) by exploiting the correlations among different labels. In particular, to reduce the negative effects of imperfect label information in obtaining label correlations, we decompose the multilabel information of data instances into a low-dimensional space and then employ the reduced label representation to guide the feature selection phase via a joint sparse regression framework. Empirical studies on both synthetic and real-world datasets demonstrate the effectiveness and efficiency of the proposed MIFS framework.

Robust feature selection using label enhancement and β-precision fuzzy rough sets for multilabel fuzzy decision system

Text datasets have many terms, which decrease the classification accuracy. According to the high-dimensional text data, there are more challenges for these methods. Each classification method has strengths and weaknesses in its feature selection function. Therefore, ensembling should be used for better classifications and exploitation of strengths. In this paper, for the first time, we have presented an ensemble multi-label (ML) feature selection method for the text datasets using the Geometric-Mean (GM) aggregation approach. For this purpose, we have used four multi-label feature selection (MLFS) algorithms with different structures to achieve a good result. Then, the performance and results obtained by the GM method are compared with the four algorithms and based on the six classification criteria on three ML datasets with text domains. According to the obtained outputs, it is possible to realize the ability of the GMA (proposed method) method in using strengths and ignoring weaknesses in the path of feature selection, and be more accurate. Finally, according to experiments and obtained results, superiority of the GMA over other methods can be well seen.

Multi-label feature selection, which is an efficient and effective pre-processing step in machine learning and data mining, can select a feature subset that contains more contributions for multi-label classification while improving the performance of the classifiers. In real-world applications, an instance may be associated with multiple related labels with different relative importances, and the process of obtaining different features usually requires different costs, containing money, and time, etc. However, most existing works with regard to multi-label feature selection do not take into consideration the above two critical issues simultaneously. Therefore, in this paper, we exploit the idea of neighborhood granularity to enhance the traditional logical labels into label distribution forms to excavate the deeper supervised information hidden in multi-label data, and further consider the effect of the test cost under three different distributions, simultaneously. Motivated by these issues, a novel test cost multi-label feature selection algorithm with label enhancement and neighborhood granularity is designed. Moreover, the proposed algorithm is tested upon ten publicly available benchmark multi-label datasets with six widely-used metrics from two different aspects. Finally, two groups of experimental results demonstrate that the proposed algorithm achieves the satisfactory and superior performance over other four state-of-the-art comparing algorithms, and it is effective for improving the learning performance and decreasing the total test costs of the selected feature subset.

Feature selection for multilabel classification with missing labels via multi-scale fusion fuzzy uncertainty measures

Multiple reference points-based multi-objective feature selection for multi-label learning

Label Correlation Guided Feature Selection for Multi-label Learning

In multi-label classification, each example can be associated with multiple labels simultaneously. The task of learning from multilabel data can be addressed by methods that transform the multi-label classification problem into several single-label classification problems. The binary relevance approach is one of these methods, where the multilabel learning task is decomposed into several independent binary classification problems, one for each label in the set of labels, and the final labels for each example are determined by aggregating the predictions from all binary classifiers. However, this approach fails to consider any dependency among the labels. In this paper, we consider a simple approach which can be used to explore labels dependency aiming to accurately predict label combinations. An experimental study using decision trees, a kernel method as well as Naive Bayes as base-learning techniques shows the potential of the proposed approach to improve the multi-label classification performance.

Due to the existence of text data, multi-label (ML) text classification is an essential task in machine learning. Feature selection is an essential and effective preprocess to enhance the learning process. Choosing a Multi-Label Feature Selection (MLFS) algorithm is the most basic, critical, and sensitive choice in ML classification operations. If this choice is based on a criterion, it cannot be attributed to always being sound. Choosing the best algorithm must be evaluated using several different criteria to be examined from different aspects. In this article, we turn the issue into an election and use the Weighted Borda Count method for voting. We do the voting in three stages continuously so that a subset of different features does the voting. In the second stage, voting of different methods is done with six criteria, and each criterion selects the methods in order of priority from the beginning to the end. Voting steps 1 and 2 are performed on eighteen text datasets used. Finally, in the final voting stage, the methods are evaluated and voted on by different text datasets. The final result of the voting in the third stage shows the desired MLFS methods based on their performance from beginning to end. According to the experiments performed and the results obtained, it can be seen that the selection of the algorithm based on several different criteria and considering the overall performance of the algorithm will be better than the selection based on one criterion.

Enhanced multi-label feature selection considering label-specific relevant information

Feature selection has attracted considerable attention due to the wide application of multi-label learning. However, previous methods do not fully consider the relationship between feature sets and label sets but devote attention to either of them. Furthermore, conventional multi-label learning utilizes logical labels to estimate relevance between feature sets and label sets so that the importance of corresponding labels cannot be well reflected. Additionally, numerous irrelevant and redundant labels degrade the classification performance of models. To this end, we propose a multi-label feature selection method named Robust multi-label Feature Selection with shared Label Enhanced (RLEFS). First, we obtain a robust label enhancement term by reconstructing labels from logical labels to numerical labels and imposing \(l_{2,1}\)-norm onto the label enhancement term. Second, RLEFS utilizes the robust label enhancement term to share the similar latent semantic structure between feature matrix and label matrix. Third, local structure is considered to ensure the consistency of label information during the feature selection process. Finally, we integrate the above terms into one joint learning framework, and then, a simple but effective optimization method with provable convergence is proposed to solve RLEFS. Experimental results demonstrate the classification superiority of RLEFS in comparison with seven state-of-the-art methods.