Summarize posterior rank uncertainty for snap years

Ranks year-level snap indices within each retained draw, with rank 1 assigned to the highest snap index.

Usage

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

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.

A data frame with year-level index means and rank probabilities.