Skip to contents

Telescoping zoom: fine detail in a focus area, coarse elsewhere

Source: R/zoom.R
zoom_geoscale.Rd

Builds a new geoframe that keeps focus atoms at full resolution and collapses everything else into progressively coarser rings drawn from levels. The result is a partition of the atoms, carried as a geoframe.

Usage

zoom_geoscale(x, focus, levels = NULL, name = "zoom", label_rest = "%s_rest")

Arguments

x

A Geoscale.

focus

Character vector of atom codes to keep at full resolution.

levels

Ordered geoframes to build rings from, coarsest first. Defaults to every geoframe of x except the atom layer.

name

Name of the new geoframe. Default "zoom".

label_rest

sprintf format for a ring's code, with %s the parent code. Default "%s_rest".

Value

A Geoscale with geoframes levels[1], name and the atom layer; weights and geometry carried through unchanged.

Details

With focus atoms and levels = c("nuts0", "nuts1", "nuts2") (coarsest first), each remaining atom joins the finest ring that also contains a focus atom, so the cut telescopes outward:

  • the focus atoms themselves, individually;

  • the rest of each nuts2 holding a focus atom;

  • the rest of each nuts1 holding one of those;

  • the rest of each nuts0 holding one of those;

  • every other atom, grouped at levels[1].

The intermediate geoframes are dropped. A ring like "rest of nuts1" spans several nuts2, so the cut cannot nest with the levels it was carved from; only levels[1] and the atom layer are kept beside it. That is checked, not assumed — see geoscale_nests().

See also

filter_geoscale() to sample, prune_geoscale() to coarsen uniformly, geoscale_nests() for the guarantee this relies on.

Examples

gs <- geoscale_example()
z <- zoom_geoscale(gs, focus = "A1", levels = c("country", "state"))
geoscale_geoframes(z)
#> [1] "country" "zoom"    "atom"   
geoscale_regions(z, "zoom")
#> [1] "A1"      "N1_rest" "N_rest"  "S"