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Lay out child geography around a parent

Source: R/child-layout.R
layout_children.Rd

Computes a renderer-neutral child expansion in projected map units. Child features move radially away from the parent anchor, then a bounded axis-aligned bounding-box or circle solver separates collisions while an attraction term and bearing guard preserve the source geography's mental map. The returned base offsets are algorithmic movement; manual/editorial movement belongs in a dragmapr_state and can be composed downstream.

Usage

layout_children(
  x,
  id_col,
  parent = NULL,
  parent_geometry = NULL,
  scale = 1.6,
  radial_kick = NULL,
  gap = NULL,
  collision = c("bbox", "circle"),
  attraction = 0.08,
  max_bearing_drift = 0.22,
  bounds = NULL,
  max_iter = 180L
)

Arguments

x

Projected polygon sf object containing child features.

id_col

Stable unique feature identifier column.

parent

Optional single parent identifier recorded in the output.

parent_geometry

Optional parent sf, sfc, or sfg geometry whose representative point anchors the expansion. Defaults to the union of x.

scale

Radial expansion multiplier applied to source vectors.

radial_kick

Additional outward movement in projected map units. Defaults to two percent of the child layer's bounding-box diagonal.

gap

Minimum separation in projected map units. Defaults to one percent of the child layer's bounding-box diagonal.

collision

Collision approximation: feature bounding boxes or centroid circles derived from those boxes.

attraction

Fraction of the remaining distance to the geographic target applied during each refinement iteration.

max_bearing_drift

Maximum angular drift from the source bearing, in radians.

bounds

Optional bounding box supplied as an sf/sfc object, st_bbox, or numeric c(xmin, ymin, xmax, ymax).

max_iter

Maximum collision-refinement iterations.

Value

An explodemap_child_layout with offsets, composed geometry, source geometry, diagnostics, and parameters. offsets contains stable IDs, source/final anchors, base offsets, distance, bearing, bearing drift, and residual collision counts.