Table 5 Summary of hyperparameters and hyperparameter optimization (HPO) methods for various machine learning algorithms.

From: Ensemble deep learning and EfficientNet for accurate diagnosis of diabetic retinopathy

ML algorithm

Main HPs

Optional HPs

HPO methods

Libraries

Ridge & lasso

Alpha

BO-GP

Skopt

Logistic regression

Penalty, c, solver

BO-TPE, SMAC

Hyperopt, SMAC

KNN

n_neighbors

Weights, p, algorithm

BOs, Hyperband

Skopt, Hyperopt, SMAC, Hyperband

SVM

C, kernel, epsilon (for SVR)

Gamma, coef0, degree

BO-TPE, SMAC, BOHB

Hyperopt, SMAC, BOHB

NB

Alpha

BO-GP

Skopt

DT

Criterion, max_depth, min_samples_split, min_samples_leaf, max_features, splitter, min_weight_fraction_leaf, max_leaf_nodes

GA, PSO, BO-TPE, SMAC, BOHB

TPOT, Optunity, SMAC, BOHB

RF & ET

n_estimators, max_depth, criterion, min_samples_split, min_samples_leaf, max_features, splitter, min_weight_fraction_leaf, max_leaf_nodes

GA, PSO, BO-TPE, SMAC, BOHB

TPOT, Optunity, SMAC, BOHB

XGBoost

n_estimators, max_depth, learning_rate, subsample, colsample_bytree, min_child_weight, gamma, alpha, lambda

GA, PSO, BO-TPE, SMAC, BOHB

TPOT, Optunity, SMAC, BOHB

Voting

Estimators, voting weights

GS

Sklearn

Bagging

Base_estimator, n_estimators

max_samples, max_features

GS, BOs

Sklearn, Skopt, Hyperopt, SMAC

AdaBoost

Base_estimator, n_estimators, learning_rate

BO-TPE, SMAC

Hyperopt, SMAC

Deep learning

Number of hidden layers, ‘units’ per layer, loss, optimizer, Activation, learning_rate, dropout rate, epochs, batch_size, early stop patience, number of frozen layers (if transfer learning is used)

PSO, BOHB

Optunity, BOHB

Hierarchical clustering

n_clusters, distance_threshold

Linkage

BOs, Hyperband

Skopt, Hyperopt, SMAC, Hyperband

DBSCAN

eps, min_samples

BO-TPE, SMAC, BOHB

Hyperopt, SMAC, BOHB

Gaussian mixture

n_components

covariance_type, max_iter, tol

BO-GP

Skopt

PCA

n_components

svd_solver

BOs, Hyperband

Skopt, Hyperopt, SMAC, Hyperband

LDA

n_components

solver, shrinkage

BOs, Hyperband

Skopt, Hyperopt, SMAC, Hyperband