Expand a structured model so that it is represented in an unstructured
format requiring a more verbose description. Currently,
this is only applicable for mp_tmb_model_spec objects
that have explicit flows
(e.g. mp_per_capita_flow). For such models, mp_expand
produces a model with expression lists composed entirely of plain R
formulas.
Examples
sir = mp_tmb_library("starter_models", "sir", package = "macpan2")
print(sir)
#> ---------------------
#> Default values:
#> ---------------------
#> quantity value
#> beta 0.2
#> gamma 0.1
#> N 100.0
#> I 1.0
#> R 0.0
#>
#> ---------------------
#> Before the simulation loop (t = 0):
#> ---------------------
#> 1: S ~ N - I - R
#>
#> ---------------------
#> At every iteration of the simulation loop (t = 1 to T):
#> ---------------------
#> 1: mp_per_capita_flow(from = "S", to = "I", rate = "beta * I / N",
#> abs_rate = "infection")
#> 2: mp_per_capita_flow(from = "I", to = "R", rate = "gamma", abs_rate = "recovery")
#>
print(mp_expand(sir))
#> ---------------------
#> Default values:
#> ---------------------
#> quantity value
#> beta 0.2
#> gamma 0.1
#> N 100.0
#> I 1.0
#> R 0.0
#>
#> ---------------------
#> Before the simulation loop (t = 0):
#> ---------------------
#> 1: S ~ N - I - R
#>
#> ---------------------
#> At every iteration of the simulation loop (t = 1 to T):
#> ---------------------
#> 1: infection ~ S * (beta * I/N)
#> 2: recovery ~ I * (gamma)
#> 3: S ~ S - infection
#> 4: I ~ I + infection - recovery
#> 5: R ~ R + recovery
#>