Calculate percentage using parallel computing — lsm_percentage

Calculate focal ("moving window") values for each cell using the mean from r.neighbors module and multiplies by 100.

Usage

lsm_percentage_parallel(
  input,
  output = NULL,
  zero_as_na = FALSE,
  buffer_radius,
  buffer_circular = FALSE,
  grid_size,
  grid_delete = TRUE,
  nprocs = 1,
  memory = 300
)

Arguments

input: [character=""]
Habitat map, following a binary classification (e.g. values 1,0 or 1,NA for habitat,non-habitat).
output: [character=""]
Habitat map output name inside GRASS Data Base.
zero_as_na: [logical=""]
buffer_radius: [numeric()]
Integer indicating window size.
grid_size: [numeric()]
Integer indicating window size.
nprocs: [numeric()]
memory: [numeric()]
buffer_cirular: [logical=""]

Examples

library(lsmetrics)
library(terra)

# read habitat data
r <- lsmetrics::lsm_toy_landscape(type = "binary")

# plot
plot(r, legend = FALSE, axes = FALSE, main = "Binary habitat")
plot(as.polygons(r, dissolve = FALSE), lwd = .1, add = TRUE)
plot(as.polygons(r), add = TRUE)
text(r)


# find grass
path_grass <- system("grass --config path", inter = TRUE) # windows users need to find the grass gis path installation, e.g. "C:/Program Files/GRASS GIS 8.3"

# create grassdb
rgrass::initGRASS(gisBase = path_grass,
                  SG = r,
                  gisDbase = "grassdb",
                  location = "newLocation",
                  mapset = "PERMANENT",
                  override = TRUE)
#> gisdbase    grassdb 
#> location    newLocation 
#> mapset      PERMANENT 
#> rows        16 
#> columns     16 
#> north       7525600 
#> south       7524000 
#> west        234000 
#> east        235600 
#> nsres       100 
#> ewres       100 
#> projection:
#>  PROJCRS["unknown",
#>     BASEGEOGCRS["unknown",
#>         DATUM["World Geodetic System 1984",
#>             ELLIPSOID["WGS 84",6378137,298.257223563,
#>                 LENGTHUNIT["metre",1]],
#>             ID["EPSG",6326]],
#>         PRIMEM["Greenwich",0,
#>             ANGLEUNIT["degree",0.0174532925199433],
#>             ID["EPSG",8901]]],
#>     CONVERSION["UTM zone 23S",
#>         METHOD["Transverse Mercator",
#>             ID["EPSG",9807]],
#>         PARAMETER["Latitude of natural origin",0,
#>             ANGLEUNIT["degree",0.0174532925199433],
#>             ID["EPSG",8801]],
#>         PARAMETER["Longitude of natural origin",-45,
#>             ANGLEUNIT["degree",0.0174532925199433],
#>             ID["EPSG",8802]],
#>         PARAMETER["Scale factor at natural origin",0.9996,
#>             SCALEUNIT["unity",1],
#>             ID["EPSG",8805]],
#>         PARAMETER["False easting",500000,
#>             LENGTHUNIT["metre",1],
#>             ID["EPSG",8806]],
#>         PARAMETER["False northing",10000000,
#>             LENGTHUNIT["metre",1],
#>             ID["EPSG",8807]],
#>         ID["EPSG",17023]],
#>     CS[Cartesian,2],
#>         AXIS["(E)",east,
#>             ORDER[1],
#>             LENGTHUNIT["metre",1,
#>                 ID["EPSG",9001]]],
#>         AXIS["(N)",north,
#>             ORDER[2],
#>             LENGTHUNIT["metre",1,
#>                 ID["EPSG",9001]]]] 

# import raster from r to grass
rgrass::write_RAST(x = r, flags = c("o", "overwrite"), vname = "r")
#> Over-riding projection check
#> Importing raster map <r>...
#>    0%   6%  12%  18%  25%  31%  37%  43%  50%  56%  62%  68%  75%  81%  87%  93% 100%
#> SpatRaster read into GRASS using r.in.gdal from memory

# percentage
lsmetrics::lsm_percentage_parallel(input = "r", buffer_radius = 100, grid_size = 1000, grid_delete = FALSE, nprocs = 5)
#> Calculating proportion
#> [1] "1 of 4"
#> Calculating proportion
#> Calculating proportion
#> Calculating percentage
#> Changing the raster color
#> Cleaning rasters
#> [1] "2 of 4"
#> Calculating proportion
#> Calculating proportion
#> Calculating percentage
#> Changing the raster color
#> Cleaning rasters
#> [1] "3 of 4"
#> Calculating proportion
#> Calculating proportion
#> Calculating percentage
#> Changing the raster color
#> Cleaning rasters
#> [1] "4 of 4"
#> Calculating proportion
#> Calculating proportion
#> Calculating percentage
#> Changing the raster color
#> Cleaning rasters
#> Changing the raster color
#> Cleaning rasters
#> Warning: The command:
#> g.remove -b -f --quiet type=vector name=r_grid_temp1,r_grid_temp2,r_grid_temp3,r_grid_temp4
#> produced at least one warning during execution:
#> WARNING: No data base element files found
#> WARNING: No data base element files found
#> Warning: The command:
#> g.remove -b -f --quiet type=vector name=r_grid_temp_buf1,r_grid_temp_buf2,r_grid_temp_buf3,r_grid_temp_buf4
#> produced at least one warning during execution:
#> WARNING: No data base element files found
#> WARNING: No data base element files found

# files
# rgrass::execGRASS(cmd = "g.list", type = "raster")
# rgrass::execGRASS(cmd = "g.list", type = "vector")

# import from grass to r
v <- rgrass::read_VECT("grid_sel", flags = "quiet")
r_pct_buf100 <- rgrass::read_RAST("r_pct_buf100", flags = "quiet", return_format = "terra")

# plot
plot(r_pct_buf100, legend = FALSE, axes = FALSE, main = "Habitat percentage (buffer 100 m)")
plot(as.polygons(r, dissolve = FALSE), lwd = .1, add = TRUE)
plot(as.polygons(r), add = TRUE)
plot(v, lwd = 3, border = "blue", add = TRUE)
text(v, cex = 3, col = "blue")
text(r_pct_buf100, cex = .75)


# delete grassdb
unlink("grassdb", recursive = TRUE)