zonal_stats_ISEA3HEXAGON_grid: Get zonal stats binned in a hexagon grid

In Vizzuality/species-distribution-modelling: Vizzuality tools for species distribution modelling

Description

Given a geometry (multi) polygon object, create a ISEA-3-HEXAGON grid at the given resolution covering the geometry, apply the zonal statistics function(s) to each feature of the grid feature collection, and return the grid with calculated properties. Optionally clipping the grid by the geometry object, and saving to file.

Usage

zonal_stats_ISEA3HEXAGON_grid(fun, polygon_object, raster_object,
  grid_res = 11, remove_na = T, clip = F, out_path = F)

Arguments

fun	An optional function or character vector, as described in exact_extract exactextractr
polygon_object	A sf::sf object
raster_object	A raster::raster object
grid_res	The zoom resolution of the ISEA-3-HEXAGON grid, see dggridR::dgconstruct
clip	Boolean, clip by the polygon? Note this can be slow
out_path	Path to write the grid using sf::st_write

Value

A sf object representing the ISEA-3-HEXAGON grid covering the geometry with zonal statistics as defined by fun

Examples

polygon_path <- system.file("ext_data", "boundary-vectors", "sweden.shp", package="vspt")
polygon_object <- sf::st_as_sf(sf::st_read(polygon_path))
raster_path <- system.file("ext_data/predicted-spp-occurence-rasters/proj_rcp45_2020_Pinus.mugo_ensemble.grd", package="vspt")
raster_object <- raster::raster(raster_path, band=6, crs="+proj=longlat +datum=WGS84")
raster_object
# Make stack with area
raster_object <- raster::stack(raster_object, raster::area(raster_object))
out_path <- file.path(system.file("ext_data/predicted-spp-occurence-vectors", package="vspt"), "SWE_pinus-mugo_rcp45-2020_ensemble.geojson")
# Define function to apply
area_weighted_mean <- function(values, coverage_frac){return(weighted.mean(values[,1], values[,2]*coverage_frac, na.rm=TRUE))}
fun = area_weighted_mean
out <- zonal_stats_ISEA3HEXAGON_grid(fun, polygon_object,raster_object,grid_res = 11, remove_na = T, clip=F, out_path=out_path)
names(out)
if(require(tmap)){
  tmap_mode("view")
  tm_shape(out) + tm_fill("zstat_Pinus.mugo_EMcaByROC_mergedAlgo_mergedRun_mergedData", palette = sf::sf.colors(3), alpha=0.7, colorNA=NULL)
  }else{plot(out)}

Vizzuality/species-distribution-modelling documentation built on Oct. 31, 2019, 1:10 a.m.