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Map exposure with a classified scale

Source: R/fire_exp_map_class.R
fire_exp_map_class.Rd

fire_exp_map_class() produces a standardized map by classifying exposure into predetermined exposure classes.

Usage

fire_exp_map_class(
  exposure,
  aoi,
  classify = c("local", "landscape", "custom"),
  class_breaks,
  zoom_level,
  title = "Classified Exposure"
)

Arguments

exposure

SpatRaster (e.g. from fire_exp())

aoi

(Optional) SpatVector of an area of interest to mask exposure

classify

character, either "local", "landscape", or "custom", to specify classification scheme to use. The default is "local". If set to "custom": the parameter class_breaks must be used.

class_breaks

vector of numeric values between 0-1 of the upper limits of each custom class. Ignored unless classify = "custom". See details.

zoom_level

(Optional) numeric, set the zoom level for the basemap based on the extent of your data if defaults are not appropriate. See details. Defaults if:

  • classify = "local" or "custom" the zoom level default is 12

  • classify = "landscape" the zoom level default is 7

title

(Optional) String. A custom title for the plot. The default is "Classified Exposure"

Value

a standardized map is returned as a ggplot object

Details

This function returns a standardized map with basic cartographic elements.

The plot is returned as a ggplot object which can be exported/saved to multiple image file formats.

This function visualizes the outputs from fire_exp() with classes. Classes can be chosen from the pre-set "local" and "landscape" options, or customized. To use a custom classification scheme, it should be defined with a list of numeric vectors defining the upper limits of the breaks. A Nil class is added automatically for exposure values of exactly zero.

Local classification breaks are predefined as c(0.15, 0.3, 0.45, 1):

  • Nil (0)

  • 0 - 0.15

  • 0.15 - 0.3

  • 0.3 - 0.45

  • 0.45 - 1

Landscape classification breaks are predefined as c(0.2, 0.4, 0.6, 0.8, 1):

  • Nil (0)

  • 0 - 0.2

  • 0.2 - 0.4

  • 0.4 - 0.6

  • 0.6 - 0.8

  • 0.8 - 1

Spatial reference

This function dynamically pulls map tiles for a base map. The inputs are projected to WGS 84/Pseudo-Mercator (EPSG:3857) to align them with the map tiles.

Zoom level

The map tile zoom level may need to be adjusted. If the base map is blurry, increase the zoom level. Higher zoom levels will slow down the function, so only increase if necessary. Reference the OpenStreetMap Wiki for more information on zoom levels.

See also

fire_exp_map_class()

Examples

# read example hazard data
hazard_file_path <- "extdata/hazard.tif"
hazard <- terra::rast(system.file(hazard_file_path, package = "fireexposuR"))

# read example area of interest geometry
geom_file_path <- "extdata/polygon_geometry.csv"
geom <- read.csv(system.file(geom_file_path, package = "fireexposuR"))

# generate example area of interest polygon with geometry
aoi <- terra::vect(as.matrix(geom), "polygons", crs = hazard)

# compute exposure
exposure <- fire_exp(hazard)

fire_exp_map_class(exposure, aoi, classify = "local")