hexify_cell_to_icosa_tri: Convert Cell ID to Icosa Triangle coordinates

In hexify: Equal-Area Hex Grids on the 'Snyder' 'ISEA' 'Icosahedron'

Convert Cell ID to Icosa Triangle coordinates

Description

Converts DGGRID-compatible cell IDs to icosahedral triangle coordinates (face, x, y). These are the coordinates produced by the 'Snyder' 'ISEA' forward projection.

Usage

hexify_cell_to_icosa_tri(cell_id, resolution, aperture = 3L)

Arguments

cell_id	Numeric vector of cell IDs (1-based)
resolution	Grid resolution level (0-30)
aperture	Grid aperture: 3, 4, or 7

Details

Compatible with 'dggridR' dgSEQNUM_to_PROJTRI().

Value

Data frame with columns:

icosa_triangle_face	Triangle face number (0-19)
icosa_triangle_x	X coordinate on triangle face
icosa_triangle_y	Y coordinate on triangle face

See Also

hexify_cell_to_quad_ij for conversion to Quad IJ, hexify_cell_to_lonlat for conversion to lon/lat

Other coordinate conversion: hexify_cell_id_to_quad_ij(), hexify_cell_to_lonlat(), hexify_cell_to_plane(), hexify_cell_to_quad_ij(), hexify_cell_to_quad_xy(), hexify_grid_cell_to_lonlat(), hexify_grid_to_cell(), hexify_icosa_tri_to_plane(), hexify_icosa_tri_to_quad_ij(), hexify_icosa_tri_to_quad_xy(), hexify_lonlat_to_cell(), hexify_lonlat_to_plane(), hexify_lonlat_to_quad_ij(), hexify_quad_ij_to_cell(), hexify_quad_ij_to_icosa_tri(), hexify_quad_ij_to_xy(), hexify_quad_xy_to_cell(), hexify_quad_xy_to_icosa_tri(), hexify_roundtrip_test()

Examples

# Get triangle coordinates for a cell
result <- hexify_cell_to_icosa_tri(cell_id = 1000, resolution = 10, aperture = 3)
print(result)

# Convert back to lon/lat using inverse projection
coords <- hexify_inverse(result$icosa_triangle_face,
                         result$icosa_triangle_x,
                         result$icosa_triangle_y)

hexify documentation built on March 1, 2026, 1:07 a.m.