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Calculate Euclidean distance via Python

Source: R/python_dist.R
python_dist.Rd

Wrapper function to call a python script for calculating Euclidean distances on landscape rasters. On first call this function imports the arcpy module and Spatial Analyst extensions then sources the Python script "dist_stats.py".

Usage

python_dist(
  pathin,
  landscape_name,
  pathout,
  SDM,
  filename = "droost_km.tif",
  scale = NULL,
  mask = NULL,
  overwrite = FALSE,
  python = NULL
)

Arguments

pathin, landscape_name

Character strings defining the filepath (pathin/landscape_name) where input rasters are located, such as those created from running python_focal_prep() or update_roosts()

pathout, SDM

Additional character strings defining the filepath (pathout/SDM/landscape_name) where output raster should be written

filename

name of the output raster, including file extension; default is 'droost_km.tif', the name of the predictor required by the waterbird models

scale

Optional character string for scaling the results; See Details

mask

Optional SpatRaster or character string giving the filepath to a raster that should be used to mask the output, e.g. a study area boundary

overwrite

Logical; passed to terra::writeRaster(); does not apply to the intermediate step of writing droost_raw.tif

python

Optional filepath to the preferred version of arcpy, passed to reticulate::use_python. See details.

Value

Nothing; all files written to pathout/SDM/landscape_name

Details

This function calls the dist_stats.py script to calculate the Euclidean distance for all cells in the input raster without a value to the nearest cell with a value (e.g., for calculating distance to a crane roost or a stream).

Raw python results will be written to pathin/landscape_name/droost_raw.tif, and then optionally scaled and/or masked, before writing the final output to pathout/SDM/landscape_name/. Currently supported scale options include: km to divide the results by 1000 and return distances in kilometers or sqrt to take the square root of the results. Note that the initial raw output from dist_stats.py to pathin/landscape_name/droost_raw.tif will not overwrite existing rasters; old versions must be deleted before re-running.

Important: This function requires the availability of arcpy and Spatial Analyst extensions. Use the python argument to specify the local pathway to arcpy, particularly if other versions of Python are installed. For example: 'C:/Program Files/ArcGIS/Pro/bin/Python/envs/arcgispro-py3/python.exe'. Note that the python argument is applied only on the first use within each session, and must be repeated in each session.

Examples

# See vignette