Summarize or plot directional load for multiple values

fire_exp_dir_multi() summarizes the directional vulnerability load for multiple points in a study area in a table or a plot.

Usage

fire_exp_dir_multi(exposure, values, plot = FALSE, full = FALSE, title, ...)

Arguments

exposure

SpatRaster from fire_exp()

values

Spatvector of value as a point or simplified polygon

plot

Boolean, when TRUE: returns a standardized directional plot. The default is FALSE.

full

Boolean. Ignored when plot = FALSE. When TRUE: all 3 transect segments must be viable. when FALSE: only the segments from seg2 and seg3 are considered (Default)

title

(Optional) String. Ignored when plot = FALSE. A custom title for the plot. The default is "Directional Vulnerability for Multiple Values"

...

arguments passed to fire_exp_dir().

Value

a data.frame of the features with attributes: value featureID, degree, seg1 (binary), seg2 (binary), seg3 (binary), full (binary), outer (binary). Unless:

• plot = TRUE: a standardized plot as a ggplot object

Details

This function summarizes multiple directional vulnerability assessments into a single table or plot. The plot is based on the methods presented in Beverly and Forbes 2023. For each degree, the frequency of input values with a continuous pathway at that trajectory is found. This summary can be useful in identifying trends in directional exposure to values within a regional area of interest.

Continuous pathways can be assessed for the full span of all three directional assessment transect segments, or limited to the outer two segments with the full parameter. If the values being assessed are variable sizes and being represented as points, it is recommended this parameter remains set to FALSE. The inner segment is sensitive to the size of the value when a point is used. Adjusting the parameters for fire_exp_dir() is also supported. See details in fire_exp_dir() for more information.

References

Beverly JL, Forbes AM (2023) Assessing directional vulnerability to wildfire. Natural Hazards 117, 831-849. DOI

Examples

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

# generate 10 random example points within the hazard extent
e <- terra::buffer(terra::vect(terra::ext(hazard), crs = hazard), -15500)
points <- terra::spatSample(e, 10)

# compute exposure metric
exposure <- fire_exp(hazard)

# plot directional load for multiple points
fire_exp_dir_multi(exposure, points, plot = TRUE, interval = 10)