Fold-change in non-core rate, from a reference month to now

For each of several sources, compare each popularity stratum's trailing 12-month rate at a fixed reference month against its most recent value. A fixed reference month (rather than each stratum's own peak) is used deliberately: individual per-stratum peaks are noisy, especially for sparser low-popularity strata where a single active month can dominate a small repo-month denominator, so anchoring on one shared calendar month both avoids cherry-picking and keeps strata/sources comparable.

Usage

step_change_tbl(
  issue_authors_tbl,
  repo_tbl,
  sources,
  n_strata = 4L,
  metric = "issues",
  contrib_threshold = 0.01,
  window = 12L,
  ref_date = as.Date("2021-01-01")
)

Arguments

issue_authors_tbl

As returned by fetch_issue_authors().

repo_tbl

As returned by build_repo_tbl().

sources

Character vector of source_name values to include (see issue_rate_tbl()).

n_strata

Number of popularity strata, passed to issue_rate_tbl(). n_strata = 1 pools every repo into a single, unstratified rate and drops popularity_stratum from the returned tibble.

metric, contrib_threshold, window

Passed to issue_rate_tbl().

ref_date

Reference Date (first-of-month) to compare against the latest available month.

Value

A tibble: source, popularity_stratum, rate_ref, rate_latest, step_change (rate_latest / rate_ref), latest_month.

Examples

if (FALSE) { # \dontrun{
fc <- step_change_tbl (issue_authors_tbl, repo_tbl, c ("cran", "npm"))
plot_step_change (fc)
} # }