fire_exp_extract_vis: Visualize exposure to values in a summary table or map

In fireexposuR: Compute and Visualize Wildfire Exposure

Visualize exposure to values in a summary table or map

Description

fire_exp_extract_vis() standardizes the visualization of outputs from fire_exp_extract() as a summary table or a map by classifying exposure into predetermined exposure classes.

Usage

fire_exp_extract_vis(
  values_ext,
  classify = c("local", "landscape", "custom"),
  class_breaks,
  method = c("max", "mean"),
  map = FALSE,
  zoom_level,
  title = "Classified Exposure to Values"
)

Arguments

values_ext	Spatvector of points or polygons from fire_exp_extract()
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. Ignored unless classify = "custom". See details.
method	character, either "max" or "mean". If values_ext are polygons the default is "max".This parameter is ignored when values_ext are point features.
map	Boolean. When TRUE, a map is returned as a ggplot object. The default is FALSE.
zoom_level	(Optional). Numeric. Ignored when map = FALSE. set the zoom level for the base map tile. 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. Ignored when map = FALSE. A custom title for the plot. The default is "Classified Exposure to Values"

Details

This function visualizes the outputs from fire_exp_extract() 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 when map = TRUE. 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.

Value

a summary table is returned as a data frame object, Unless: map = TRUE: a ggplot object

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

# generate random points within the aoi polygon
points <- terra::spatSample(aoi, 100)

# compute exposure
exposure <- fire_exp(hazard)

values_exp <- fire_exp_extract(exposure, points)

# summarize example points in a table
fire_exp_extract_vis(values_exp, classify = "local")

# visualize example points in standardized map
fire_exp_extract_vis(values_exp, map = TRUE)

fireexposuR documentation built on June 8, 2025, 1:48 p.m.