add_alpha: Calculate and add alpha

In trps: Bayesian Trophic Position Models using 'stan'

Calculate and add \alpha

Description

Calculate \alpha for a two source trophic position model using equations from Post 2002.

Usage

add_alpha(data, abs = FALSE)

Arguments

data	data.frame of stable isotope samples with mean values for two baselines. For aquatic ecosystems, baseline one needs to come from a benthic source and baseline two needs to come from a pelagic source. Baseline \delta^{13}C columns need to be named c1 and c2, with the consumer's \delta^{13}C column named d13c.
abs	logical that controls whether the absolute value is taken for the numerator and denominator. Default is FALSE meaning that the absolute value is not taken.

Details

\alpha = (\delta^{13}C_c - \delta ^{13}C_2) / (\delta ^{13}C_1 - \delta ^{13}C_2)

where \delta^{13}C_c is the isotopic value for consumer, \delta^{13}C_1 is the mean isotopic value for baseline 1 and \delta^{13}C_2 is the mean isotopic value for baseline 2.

Value

a data.frame that has alpha, min_alpha, and max_alpha added.

Examples

combined_iso |>
  add_alpha()

trps documentation built on April 4, 2025, 12:20 a.m.