This helper is useful for interfaces that should keep all label state, but
show only a manageable subset by default. It returns label IDs only; callers
can pass the result to label_values in drag_map_prototype() or
render_dragged_map().
Arguments
- labels
A drag label table accepted by
as_drag_labels().- max_labels
Maximum number of label IDs to return.
- prefer
Optional label IDs to keep first, for example labels from an expanded branch or labels the user has edited.
Examples
labels <- as_drag_labels(data.frame(
label_id = c("A", "B", "C"), region = c("A", "B", "C"),
label = c("A", "B", "C"), x = 1:3, y = 1:3
))
select_label_ids(labels, max_labels = 2)
#> [1] "A" "B"