actel (version 1.3.0)

transitionLayer: Calculate Transition Layer

Description

Using a previously imported shape file that has been converted to a raster (see shapeToRaster), Prepares a TransitionLayer object to be used in distance estimations (see distancesMatrix). Adapted from Grant Adams' script "distance to closest mpa".

Usage

transitionLayer(x, directions = c(16, 8, 4))

Value

A TransitionLayer object.

Arguments

x

A water raster; for example the output of shapeToRaster

directions

The number of directions considered for every movement situation during cost calculation. See the manual page linked above for more details.

Details

It is highly recommended to read the manual page regarding distances matrices before running this function. You can find it here: https://hugomflavio.github.io/actel-website/manual-distances.html

Examples

# \donttest{
# check if R can run the distance functions
aux <- c(
  length(suppressWarnings(packageDescription("raster"))),
  length(suppressWarnings(packageDescription("gdistance"))),
  length(suppressWarnings(packageDescription("sp"))),
  length(suppressWarnings(packageDescription("terra"))))

missing.packages <- sapply(aux, function(x) x == 1)

if (any(missing.packages)) {
  message("Sorry, this function requires packages '",
    paste(c("raster", "gdistance", "sp", "terra")[missing.packages], collapse = "', '"),
    "' to operate. Please install ", ifelse(sum(missing.packages) > 1, "them", "it"),
    " before proceeding.")
} else {
  # Fetch actel's example shapefile
  example.shape <- paste0(system.file(package = "actel")[1], "/example_shapefile.shp")

  # import the shape file
  x <- shapeToRaster(shape = example.shape, size = 20)

  # Build the transition layer
  t.layer <- transitionLayer(x)

  # inspect the output
  t.layer
}
rm(aux, missing.packages)
# }