Plot country-year onset/event coverage of a binary variable

Draws a country-by-year heatmap of a binary (0/1) event column: 1 years are shaded as an event, 0 years as no event, and years where the state does not appear in panel at all (e.g. before independence) or var is NA are left blank. Useful for eyeballing when and where events (e.g. conflict onsets) actually occurred, as opposed to just where a source has any data.

Usage

plot_coverage(panel, var, drop_empty = TRUE, show_labels = TRUE)

Arguments

panel

A data frame produced by build_states_panel(), containing a cow or gw column, a year column, and var.

var

Character. Name of a binary (0/1) column in panel, such as "ucdp_prio_onset".

drop_empty

Logical. If TRUE (default), drop states with zero years where var == 1 before plotting. A state that never has the event contributes a row with no blue tiles at all, which adds clutter without showing where/when events happened; set to FALSE to include these states anyway.

show_labels

Logical. If TRUE (default), label each row with its country (or cow/gw code, if panel has no country column). Set to FALSE to drop these labels, which otherwise overlap and become illegible once panel covers more than a few dozen states.

Value

A ggplot object (one tile per country-year, filled by "Event" / "No event", with unobserved country-years left blank). States are ordered top-to-bottom by their number of events, most first. Requires the ggplot2 package.

Examples

if (requireNamespace("ggplot2", quietly = TRUE)) {
  build_states_panel(1990, 2015, coding_system = "cow") |>
    add_conflict("ucdp_prio") |>
    plot_coverage("ucdp_prio_onset")

  build_states_panel(1990, 2015, coding_system = "cow") |>
    add_conflict("ucdp_prio") |>
    plot_coverage("ucdp_prio_onset", show_labels = FALSE)
}