makeCorridor: Calculate cost corridors for a path

In andresgmejiar/lbmech: A Package to Study the Mechanics of Landscape and Behavior

Calculate cost corridors for a path

Description

A function to automatically perform the raster arithmetic necessary to calculate the cost-of-travel for paths with multiple waypoints, and the predicted cost of taking a detour to any arbitrary point in the landscape (a 'corridor'). getCosts must have been run before this tool can be used.

Usage

makeCorridor(rasters = tempdir(), order, costs = "all", name = NULL)

Arguments

rasters	One of either a character string or multilayer SpatRaster. If character string, it represents the filepath to the workspace used as dir for the previous functions. Default is tempdir() but unless you are not following best practices you will have to change it to your output directory. If multilayer SpatRaster, it should be the output (or identical in form) to the getCosts function with "object" %in% output.
order	A character vector containing the desired path in order of visited nodes. For example, to visit "A" then "B" then "C" then "A" the vector would be c("A","B","C","A"). Note that these MUST correspond to the ID names for the from features used in the getCosts function and must have previously been calculated
costs	A character vector containing any combination of pre-calculated cost names (e.g. dt for time, dW_l for work using energyCosts) if the input world data.table is the output of of the calculateCosts function. This selects which types of costs will be calculated. costs = 'all' is shorthand for costs = c("dt","dW_l","dE_l") while costs = 'energetics' is shorthand for c("dW_l","dE_l"). Default is 'all'. Note that these must have previously been calculated.
name	A character vector representing the outname in getCosts. If none is provided, it will be the name of the variable passed to the function in the from slot. If length(costs) == 1, a Raster* If length(costs) > 1 a list of Raster* with one slot for each cost.

Value

Rasters representing cost corridors.

Examples

# Generate a DEM
n <- 5
dem <- expand.grid(list(x = 1:(n * 100),
                        y = 1:(n * 100))) / 100
dem <- as.data.table(dem)
dem[, z := 250 * exp(-(x - n/2)^2) + 
      250 * exp(-(y - n/2)^2)]
dem <- rast(dem)
ext(dem) <- c(10000, 20000, 30000, 40000)
crs(dem) <- "+proj=lcc +lat_1=48 +lat_2=33 +lon_0=-100 +datum=WGS84"

# Export it so it doesn't just exist on the memory
dir <- tempdir()
writeRaster(dem, paste0(dir,"/DEM.tif"),overwrite=TRUE)


# Import raster, get the grid
dem <- rast(paste0(dir,"/DEM.tif"))
grid <- makeGrid(dem = dem, nx = n, ny = n, sources = TRUE)

# Import the data lying between x = (12000,16000) and y = (32000,36000)
region <- ext(c(12000,16000,32000,36000))
region <- as.polygons(region)
crs(region) <- crs(grid)

# Generate five random points that fall within the region
points <- data.table(ID = 1:5,
                     x = runif(5, ext(region)[1], ext(region)[2]),
                     y = runif(5, ext(region)[3], ext(region)[4]))
                     
# Make a world but limit it to the DEM grid size
defineWorld(source = grid, cut_slope = 0.5, 
            res = res(dem), dir = dir, overwrite=TRUE)
            
# Calculate cost rasters
costRasters  <- getCosts(region, from = points, dir = dir,
                         destination = 'all',
                         polygons = 'center',
                         costs = 'all', costFUN = energyCosts,
                         output = c('object','file'),
                         m = 70, v_max = 1.5, BMR = 76, k = 3.5, s = 0.05, l_s = 1,
                         L = 0.8)
                        
# Calculating the corridors from a list of RasterStacks,
# with path 1 -> 2 -> 4 -> 1 -> 5
corridors <- makeCorridor(rasters = costRasters, order = c(1,2,5,1,4),)

#### Example 2:
# Calculating the corridors from a workspace directory
# with path 1 -> 2 -> 4 -> 1 -> 5
corridors <- makeCorridor(rasters = dir, name = 'points', 
                          order = c(1,2,5,1,4))

andresgmejiar/lbmech documentation built on Feb. 2, 2025, 12:37 a.m.