Update body composition during simulation (Mid-level) — update_body

Updates body composition as fish grows or changes condition Used during simulation loops - assumes pre-validated inputs

Usage

update_body_composition(
  old_weight,
  new_weight,
  old_composition = NULL,
  processed_composition_params
)

Arguments

old_weight: Previous weight (g)
new_weight: New weight (g)
old_composition: Previous composition (optional)
processed_composition_params: List with processed composition parameters

Value

A named list with the same 13 elements as calculate_body_composition, describing the body composition at new_weight. If old_composition is supplied, an additional element changes is appended — a named list with five numeric scalars: weight_change, water_change, protein_change, fat_change, and energy_density_change (all in the same units as the corresponding composition elements).

Examples

params <- list(water_fraction = 0.72, fat_energy = 36450,
               protein_energy = 17990, max_fat_fraction = 0.30)
old <- calculate_body_composition(weight = 100,
                                  processed_composition_params = params)
update_body_composition(old_weight = 100, new_weight = 110,
                        old_composition = old,
                        processed_composition_params = params)
#> $total_weight
#> [1] 110
#> 
#> $water_g
#> [1] 79.2
#> 
#> $protein_g
#> [1] 17.15258
#> 
#> $ash_g
#> [1] 1.973042
#> 
#> $fat_g
#> [1] 11.67437
#> 
#> $water_fraction
#> [1] 0.72
#> 
#> $protein_fraction
#> [1] 0.1559326
#> 
#> $ash_fraction
#> [1] 0.01793674
#> 
#> $fat_fraction
#> [1] 0.1061307
#> 
#> $energy_density
#> [1] 6673.69
#> 
#> $total_energy
#> [1] 734105.9
#> 
#> $total_fraction
#> [1] 1
#> 
#> $balanced
#> [1] TRUE
#> 
#> $changes
#> $changes$weight_change
#> [1] 10
#> 
#> $changes$water_change
#> [1] 7.2
#> 
#> $changes$protein_change
#> [1] 1.670393
#> 
#> $changes$fat_change
#> [1] 0.9436867
#> 
#> $changes$energy_density_change
#> [1] -22.89148
#> 
#>