method_shepherd: Shepherd method

In polehalieutique/demerstem: This package aims to falicitate Fish stock assessement for west african partners involved in the EU DEMERSTEM project

Shepherd method

Description

method_shepherd returns an estimation of growth parameters K and L_inf (growth coefficient and growth asymptotic length) from Von Bertallanfy equation and the value of objective function.

Usage

method_shepherd(data_freq, K, L_inf, step_class, plot = FALSE)

Arguments

data_freq	input dataset data_freqle
K	range aof tested values for K
L_inf	range of tested valyes for L_inf
step_class	length step between two length class
plot	FALSE by default. IF TRUE, print plot of S
title	fraction of the title in the plots

Examples

data(length_frequency)
data_freq <- length_frequency %>%  group_by(lclass, month) %>%  dplyr::summarise(total_sampling=sum(frequence, na.rm = T))
lmax <- 48 # choose lmax according to some bibliography
K <- seq(0.33, 0.40, 0.01)
L_inf <- seq(0.95*lmax, 1.05 * lmax, 0.01)
step_class <- 1
method_shepherd(data_freq, K, L_inf, step_class,  plot=F)

polehalieutique/demerstem documentation built on Aug. 4, 2024, 5:12 a.m.