Smoothed density (isobands) layer — viz

The viz_smooth function creates smoothed density contours (isobands) from a set of spatial points. It is a wrapper around contour-based density estimation, with styling optimized for smooth thematic visualizations.

Usage

viz_smooth(
  map,
  data = NULL,
  var = NULL,
  id = NULL,
  nb = 1e+05,
  bandwidth = NULL,
  fixbandwidth = FALSE,
  thresholds = NULL,
  cellSize = NULL,
  stroke = "white",
  strokeOpacity = 0.8,
  strokeWidth = 0.3,
  shadow = TRUE,
  fill = NULL,
  colors = "RdPu",
  opacity = NULL,
  fillOpacity = 0.6,
  tip = NULL,
  tipstyle = NULL,
  coords = "geo",
  legend = TRUE,
  leg_pos = c(10, 10),
  ...
)

Arguments

map: A geoviz map created with viz_create.
data: A spatial dataframe Use data to enable iteration over features.
var: character or numeric. Optional. Variable used to weight points.
id: character. Optional. Layer identifier.
nb: numeric. Optional. Number of sampled points used for density estimation (default 100000).
bandwidth: numeric. Optional. Bandwidth used for density computation.
fixbandwidth: logical. Optional. Whether to scale bandwidth by zoom factor (default FALSE).
thresholds: numeric. Optional. Number of contour levels.
cellSize: numeric. Optional. Grid cell size for density computation.
stroke: character. Optional. Stroke color (default "white").
strokeOpacity: numeric. Optional. Stroke opacity (default 0.8).
strokeWidth: numeric. Optional. Stroke width (default 0.3).
shadow: logical. Optional. Whether to add a shadow filter (default TRUE).
fill: character or function. Optional. Single fill color (used if colors is not defined).
colors: character. Optional. Name of a Dicopal sequential palette (default "RdPu"). See https://observablehq.com/@neocartocnrs/dicopal-library.
opacity: numeric. Optional. Global opacity.
fillOpacity: numeric. Optional. Fill opacity for polygons (default 0.6).
tip: logical or function. Optional. Tooltip function; if TRUE displays all properties.
tipstyle: list. Optional. Custom tooltip styling.
coords: character. Optional. Coordinate system (default "geo"). One of: "geo", "svg".
legend: logical. Optional. Whether to display legend (default TRUE).
leg_pos: numeric vector. Optional. Legend position (default c(10, 10)).
...: Additional SVG attributes (e.g. strokeDasharray, opacity, strokeLinecap, etc.).

Examples

library(sf)
world <- st_read(
  system.file("gpkg/world.gpkg", package = "geoviz"),
  quiet = TRUE
)
cities <- st_read(
  system.file("gpkg/cities.gpkg", package = "geoviz"),
  quiet = TRUE
)

viz_create(projection = "EqualEarth") |>
viz_path(datum = world, fill = "#f1f3f5") |>
viz_smooth(data = cities, var = "population") |>
viz_render()