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Create a choropleth map of polygon-level values

Source: R/choropleth.R
choropleth.Rd

Creates a choropleth map from an `sf` object containing polygon-level reporting values, 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,
  ...,
  basemaps = c("Esri.WorldGrayCanvas", "OpenStreetMap", "Esri.WorldImagery")
)

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().

basemaps

Character vector of basemap providers for mode = "view". The first provider is shown initially; the others are available in the layer control. Defaults to "Esri.WorldGrayCanvas", "OpenStreetMap", and "Esri.WorldImagery". Ignored in static mode. Passed to tmap::tm_basemap().

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")
#> Registered S3 method overwritten by 'stars':
#>   method                  from
#>   st_interpolate_aw.stars sf  

if (FALSE) { # \dontrun{
choropleth(test, value = "amount_sum", id = "areaname", mode = "view")
choropleth(test, value = "amount_sum", mode = "view",
           basemaps = "Esri.WorldImagery")
} # }