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Export a variable-rate prescription map for farm machinery

Source: R/export_prescription.R
export_prescription.Rd

Writes a prescription layer (an sf polygons object or a raster from variable_rate_N / farm_balance) in one of the formats accepted by the on-board monitors of modern tractors and sprayers. Supported formats: plain Shapefile, GeoJSON, KML, GeoPackage, John Deere-ready Shapefile, Trimble- ready Shapefile and ISOXML TASKDATA (ISOBUS ISO 11783-10).

Usage

export_prescription(
  x,
  path,
  format = NULL,
  dose_field = NULL,
  area_min = 1,
  isoxml_opts = list()
)

Arguments

x

Input map. Either an sf polygons object (as returned by farm_balance) or a RasterLayer / SpatRaster (as returned by variable_rate_N). Rasters are polygonised via terra::as.polygons() before export.

path

For single-file formats, the output path (with the proper extension: .shp, .geojson, .kml, .gpkg). For ISOXML, the output directory (the TASKDATA.XML file will be created inside).

format

Character. One of "shp", "geojson", "kml", "gpkg", "johndeere", "trimble", "isoxml". Case-insensitive; if NULL, inferred from the file extension.

dose_field

Character. Name of the numeric column carrying the N rate (kg N ha\(^{-1}\)). Defaults try "N_target", "dose", "rate" in that order.

area_min

Numeric. Drop polygon slivers smaller than this area in square metres (default 1).

isoxml_opts

Named list with metadata used by format = "isoxml": task_name, field_name, crop, product, unit, ddi_code. All optional, sensible defaults are applied.

Value

Invisibly, the sf object actually written to disk (after projection to WGS84, validity cleaning, field renaming and sliver removal).

Manufacturer-specific conventions

John Deere

WGS84 CRS, integer rate field named RATE, 8.3 DOS-safe file names.

Trimble

WGS84 CRS, rate field named TGT_RATE, unique feature ID.

ISOXML

Directory containing TASKDATA.XML following the ISOBUS ISO 11783-10 standard (VRT zones with DDI 0006 = application rate, mass per area).

See also

export_prescription_all, variable_rate_N, farm_balance

Examples

if (FALSE) { # \dontrun{
farm <- NFert::farm_balance(
  system.file("extdata/example_farm.geojson", package = "NFert"))

# Universal Shapefile
export_prescription(farm, "field_rx.shp")

# John Deere-ready Shapefile (integer RATE)
export_prescription(farm, "JD/field_rx.shp", format = "johndeere")

# ISOXML directory
export_prescription(farm, "TASKDATA", format = "isoxml",
  isoxml_opts = list(task_name = "N top-dress",
                      product = "Urea 46 pct",
                      unit = "kg/ha"))
} # }