Create choropleth map — choropleth • spatialrisk

Creates a choropleth map from an `sf` object, for example one produced by summarise_points_by_polygon(). Polygons are shaded according to values in a specified column, with clustering based on the Fisher–Jenks algorithm.

Usage

choropleth(
  data,
  value = "output",
  id = NULL,
  mode = c("plot", "view"),
  n = 7,
  legend_title = "Value",
  palette = "viridis",
  id_name = NULL,
  ...
)

Arguments

data: An object of class sf.
value: A string giving the name of the column used to shade the polygons.
id: Optional string giving the name of the column containing polygon IDs used for tooltips.
mode: A string indicating whether to create a static map ("plot", default) or an interactive map ("view").
n: Integer; number of clusters. Default is 7.
legend_title: A string giving the legend title.
palette: A palette name or vector of colors. See tmaptools::palette_explorer() for available palettes. Prefix the name with "-" to reverse the order. Default is "viridis".
id_name: Deprecated. Use id instead.
...: Additional arguments passed to tmap::tm_polygons().

Value

A tmap object (static or interactive, depending on mode).

Details

The function uses the Fisher–Jenks algorithm (style = "fisher") to classify values into n groups.

Author

Martin Haringa

Examples

test <- summarise_points_by_polygon(nl_provincie, insurance, "amount")
#> 109 points are outside any polygon.
choropleth(test, value = "amount_sum")

choropleth(test, value = "amount_sum", id = "areaname", mode = "view")