Extract posterior draws of snap indices

Computes draw-level averages of MCMC snap indicators over selected actors and years. The result is useful for system-level rupture indices and focal-actor rupture indices. Fits should be run with keep_snap_draws = "draws" for posterior uncertainty. If only snap_prob is present, the function returns a single score row and warns that intervals cannot be read as posterior intervals.

Usage

snap_index_draws(fit, actors = NULL, years = NULL, side = c("u", "v"))

Arguments

fit

a lame fit with snap-shift MCMC output, or a lame_snap_als fit. MCMC fits should be run with retained snap draws for posterior uncertainty; ALS fits contribute their snap_prob scores as one score row.

actors

optional actor names or indices. Default uses every actor on the selected side.

years

optional year/period names or indices. Default uses every period.

side

"u" for sender/row-side snap indicators or "v" for receiver/column-side indicators.

Value

A data frame with columns draw, year, side, n_actors, and snap_index.