Construct a discrete global grid system (dggs) object

Usage

dgconstruct(
  projection = "ISEA",
  aperture = 3,
  topology = "HEXAGON",
  aperture_type = "PURE",
  num_aperture_4_res = 0L,
  res = NA,
  precision = 7,
  area = NA,
  spacing = NA,
  cls = NA,
  resround = "nearest",
  metric = TRUE,
  show_info = TRUE,
  orient = "SPECIFIED",
  azimuth_deg = 0,
  pole_lat_deg = 58.28252559,
  pole_lon_deg = 11.25
)

Arguments

projection: Type of grid to use. Options are: ISEA and FULLER. Default: ISEA3H
aperture: How finely subsequent resolution levels divide the grid. Options are: 3, 4, 7 (HEXAGON only). Not all options work with all projections and topologies. Default: 3
topology: Shape of cell. Options are: HEXAGON, DIAMOND, TRIANGLE. Default: HEXAGON
aperture_type: Aperture sequence type. Options are: "PURE" (single aperture value), "MIXED43" (alternating aperture-4 and aperture-3, HEXAGON only). Default: "PURE".
num_aperture_4_res: For aperture_type = "MIXED43": number of aperture-4 resolutions before switching to aperture-3. Must be in [0, res]. Default: 0.
res: Resolution. Must be in the range [0,30]. Larger values represent finer resolutions. Appropriate resolutions can be found with dg_closest_res_to_area(), dg_closest_res_to_spacing(), and dg_closest_res_to_cls(). Default is 9, which corresponds to a cell area of ~2600 sq km and a cell spacing of ~50 km. Only one of res, area, length, or cls should be used.
precision: Round output to this number of decimal places. Must be in the range [0,30]. Default: 7.
area: The desired area of the grid's cells. Only one of res, area, length, or cls should be used.
spacing: The desired spacing between the center of adjacent cells. Only one of res, area, length, or cls should be used.
cls: The desired CLS of the cells. Only one of res, area, length, or cls should be used.
resround: What direction to search in. Must be nearest, up, or down.
metric: Whether input and output should be in metric (TRUE) or imperial (FALSE)
show_info: Print the area, spacing, and CLS of the chosen resolution.
orient: Grid orientation. Options are: "SPECIFIED" (use explicit pole and azimuth values) or "RANDOM" (random uniform orientation; use set.seed() before for reproducibility). Default: "SPECIFIED".
azimuth_deg: Rotation in degrees of grid about its pole, value in [0,360]. Default=0.
pole_lat_deg: Latitude in degrees of the pole, value in [-90,90]. Default=58.28252559.
pole_lon_deg: Longitude in degrees of the pole, value in [-180,180]. Default=11.25.

Value

Returns a dggs object which can be passed to other dggridR functions

Examples

library(dggridR)
dggs <- dgconstruct(res=20)
str(dggs)
#> List of 12
#>  $ pole_lon_deg      : num 11.2
#>  $ pole_lat_deg      : num 58.3
#>  $ azimuth_deg       : num 0
#>  $ aperture          : num 3
#>  $ aperture_type     : chr "PURE"
#>  $ num_aperture_4_res: int 0
#>  $ isMixed43         : logi FALSE
#>  $ numAp4            : int 0
#>  $ res               : num 20
#>  $ topology          : chr "HEXAGON"
#>  $ projection        : chr "ISEA"
#>  $ precision         : num 7

dggs <- dgconstruct(area=5,metric=FALSE)
#> Resolution: 14, Area (mi^2): 6.62642775724281, Spacing (mi): 2.0040855349603, CLS (mi): 2.28965624454932

# Aperture-7 hexagonal grid (ISEA7H)
dggs7 <- dgconstruct(aperture=7, res=3)

# Mixed aperture grid (ISEA43H)
dggsM <- dgconstruct(aperture_type='MIXED43', num_aperture_4_res=2, res=5)

# Random orientation (reproducible with set.seed)
set.seed(42)
dggs_r <- dgconstruct(res=4, orient='RANDOM')