Extract spatial interaction models produced by individual runs

Extracts the spatial interaction model objects produced by the individual algorithm runs performed by blvim().

Usage

sim_runs(sim)

Arguments

sim

A spatial interaction model object produced by blvim(), i.e. an object of class sim and sim_blvim

Value

A sim_list containing the available spatial interaction models produced by the algorithm runs.

For a single run, a one-element sim_list containing x is returned. For multiple runs retained with keep_runs = TRUE, the models are returned in the same order as the starting points supplied to blvim().

The function returns NULL when multiple runs were performed with keep_runs = FALSE, because only the model associated with the largest final potential was retained.

Details

See blvim() for details on how the Z and keep_runs arguments determine the number of runs and whether the resulting spatial interaction models are retained.

Use sim_logs() to extract the summary information recorded for multiple runs.

See also

blvim() for computing equilibrium spatial interaction models, sim_logs() for summaries of the individual runs, and sim_list() for collections of spatial interaction models.

Examples

distances <- french_cities_distances[1:10, 1:10] / 1000
production <- rep(1, 10)
attractiveness <- log(french_cities$area[1:10])
attractiveness <- attractiveness / sum(attractiveness) * sum(production)

# A single run produces a one-element sim_list
single <- blvim(
  distances,
  production,
  1.5,
  1 / 250,
  attractiveness,
  algorithm = "gradient"
)
length(sim_runs(single))
#> [1] 1

# Multiple runs, with all spatial interaction models retained
starts <- rbind(
  attractiveness,
  rev(attractiveness)
)

multiple <- blvim(
  distances,
  production,
  1.5,
  1 / 250,
  starts,
  algorithm = "gradient",
  keep_runs = TRUE
)

runs <- sim_runs(multiple)
length(runs)
#> [1] 2