Table 2 Candidate solutions’ coding.

From: Short-term streamflow modeling using data-intelligence evolutionary machine learning models

Estimator

IP

Description

Settings/range

EN

\(\theta _{1}\)

Penalty term, \(\alpha \)

[\(10^{-6}, 2\)]

\(\theta _{2}\)

\(L_1\)-ratio parameter, \(\rho \)

[0,1]

ELM

\(\theta _{1}\)

No. neurons in the hidden layer, L

[1, 500]

\(\theta _{2}\)

Regularization parameter C

[0.0001, 10000]

\(\theta _{3}\)

Activation function G

1: Identity; 2: Sigmoid; 3: Hyperbolic Tangent; 4: Gaussian; 5: Swish; 6: ReLU;

SVR

\(\theta _{1}\)

Loss parameter, \(\varepsilon \)

[10\(^{-5}\), 100]

\(\theta _{2}\)

Regularization parameter, C

[1, 10000]

\(\theta _{3}\)

Bandwidth parameter, \(\gamma \)

[0.001, 10]

MARS

\(\theta _{1}\)

Degree of piecewise polynomials, q

[0,3]

\(\theta _{2}\)

Penalty factor, \(\gamma \)

[1, 9]

\(\theta _{3}\)

Maximum number of terms, M

[1, 500]

XGB

\(\theta _{1}\)

Learning rate, \(\eta \)

[10\(^{-6}\), 1]

\(\theta _{2}\)

No. weak estimators, \(M_{est}\)

[10, 500]

\(\theta _{3}\)

Maximum depth, \(m_{depth}\)

[1, 20]

\(\theta _{4}\)

Regularization parameter, \(\lambda _{reg}\)

[0, 100]

  1. The IP column denotes the internal parameter used in the bioinspired algorithms’ encoding.