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Table 17 Summary of deep learning class imbalance methods

From: Survey on deep learning with class imbalance

Method

Network type

Method type

Description

ROS [23, 79]

CNN

Data

ROS of minority classes until class balance is achieved

RUS [23]

CNN

Data

RUS of majority classes until class balance is achieved

Two-phase learning [20, 23]

CNN

Data

Pre-training with RUS or ROS, then fine-tuning with all data

Dynamic sampling [21]

CNN

Data

Sampling rates adjust throughout training based on previous iteration’s class-wise F1-scores

MFE and MSFE loss [18]

MLP

Algorithm

New loss functions allow positive and negative classes to contribute to loss equally

Focal loss [88, 103]

CNN

Algorithm

New loss function down-weights easy-to-classify samples, reducing their impact on total loss

CSDNN [89]

MLP

Algorithm

CE loss function modified to incorporate a pre-defined cost matrix

CoSen CNN [19]

CNN

Algorithm

Cost matrix is learned through backpropagation and incorporated into output layer

CSDBN-DE [90]

DBN

Algorithm

Cost matrix is learned through evolutionary algorithm and incorporated into output layer

Threshold moving [23]

CNN

Algorithm

Decision threshold is adjusted by dividing output probabilities by prior class probabilities

Category centers [91]

CNN

Algorithm

Class centroids are calculated in deep feature space and K-NN method discriminates

Very-deep NNs [92]

CNN

Algorithm

CNN network depths of up to 50 layers are used to examine convergence rates

LMLE [22]

CNN

Hybrid

Triple-header hinge loss and quintuplet sampling generate more discriminative features

DOS [117]

CNN

Hybrid

Minority class over-sampled in deep feature space using K-NN and micro-cluster loss

CRL loss [118]

CNN

Hybrid

Class Rectification loss and hard sample mining produce more discriminative features