Crate h3o

The h3o library implements the H3 geospatial indexing system.

H3 is a geospatial indexing system using a hexagonal grid that can be (approximately) subdivided into finer and finer hexagonal grids, combining the benefits of a hexagonal grid with S2’s hierarchical subdivisions.

Crate features

• std - When enabled, this will cause h3o to use the standard library. In terms of APIs, std causes error types to implement the std::error::Error trait. Enabling std will also result in performance optimizations.

• geo - When enabled, you’ll be able to convert lists of H3 cell indexes from and into geometric shapes. Also enables the GeoJSON support. Requires std.

• serde - When enabled, H3 index types (cell, vertex and edge) derive serde traits.

H3 to H3O mapping

For people used to the H3 API, here is the mapping to H3O.

Indexing functions

H3	H3O
latLngToCell	LatLng::to_cell
cellToLatLng	LatLng::from
cellToBoundary	CellIndex::boundary

Index inspection functions

H3	H3O
getResolution	CellIndex::resolution
getBaseCellNumber	CellIndex::base_cell
stringToH3	str::parse
h3ToString	ToString::to_string
isValidCell	CellIndex::try_from
isResClassIII	Resolution::is_class3
isPentagon	CellIndex::is_pentagon
getIcosahedronFaces	CellIndex::icosahedron_faces
maxFaceCount	CellIndex::max_face_count

Grid traversal functions

H3	H3O
gridDisk	CellIndex::grid_disk
maxGridDiskSize	max_grid_disk_size
gridDiskDistances	CellIndex::grid_disk_distances
gridDiskUnsafe	CellIndex::grid_disk_fast
gridDiskDistancesUnsafe	CellIndex::grid_disk_distances_fast
gridDiskDistancesSafe	CellIndex::grid_disk_distances_safe
gridDisksUnsafe	CellIndex::grid_disks_fast
gridRingUnsafe	CellIndex::grid_ring_fast
gridPathCells	CellIndex::grid_path_cells
gridPathCellsSize	CellIndex::grid_path_cells_size
gridDistance	CellIndex::grid_distance
cellToLocalIj	CellIndex::to_local_ij
localIjToCell	CellIndex::try_from

Hierarchical grid functions

H3	H3O
cellToParent	CellIndex::parent
cellToChildren	CellIndex::children
cellToChildrenSize	CellIndex::children_count
cellToCenterChild	CellIndex::center_child
cellToChildPos	CellIndex::child_position
childPosToCell	CellIndex::child_at
compactCells	CellIndex::compact
uncompactCells	CellIndex::uncompact
uncompactCellsSize	CellIndex::uncompact_size

Region functions

H3	H3O
polygonToCells	geom::ToCells::to_cells
maxPolygonToCellsSize	geom::ToCells::max_cells_count
h3SetToLinkedGeo	geom::ToGeo::to_geom
destroyLinkedPolygon	N/A

Directed edge functions

H3	H3O
areNeighborCells	CellIndex::is_neighbor_with
cellsToDirectedEdge	CellIndex::edge
isValidDirectedEdge	DirectedEdgeIndex::try_from
getDirectedEdgeOrigin	DirectedEdgeIndex::origin
getDirectedEdgeDestination	DirectedEdgeIndex::destination
directedEdgeToCells	DirectedEdgeIndex::cells
originToDirectedEdges	CellIndex::edges
directedEdgeToBoundary	DirectedEdgeIndex::boundary

Vertex functions

H3	H3O
cellToVertex	CellIndex::vertex
cellToVertexes	CellIndex::vertexes
vertexToLatLng	LatLng::from
isValidVertex	VertexIndex::try_from

Miscellaneous H3 functions

H3	H3O
degsToRads	f64::to_radians
radsToDegs	f64::to_degrees
getHexagonAreaAvgKm2	Resolution::area_km2
getHexagonAreaAvgM2	Resolution::area_m2
cellAreaKm2	CellIndex::area_km2
cellAreaM2	CellIndex::area_m2
cellAreaRads2	CellIndex::area_rads2
getHexagonEdgeLengthAvgKm	Resolution::edge_length_km
getHexagonEdgeLengthAvgM	Resolution::edge_length_m
edgeLengthKm	DirectedEdgeIndex::length_km
edgeLengthM	DirectedEdgeIndex::length_m
edgeLengthRads	DirectedEdgeIndex::length_rads
getNumCells	Resolution::cell_count
getRes0Cells	CellIndex::base_cells
res0CellCount	BaseCell::count
getPentagons	Resolution::pentagons
pentagonCount	Resolution::pentagon_count
greatCircleDistanceKm	LatLng::distance_km
greatCircleDistanceM	LatLng::distance_m
greatCircleDistanceRads	LatLng::distance_rads

Modules

• error
  H3O error types.
• geom
  Bridge between H3 entities and geometrical shapes.

Structs

• BaseCell
  One of the 122 base cells.
• Boundary
  Boundary in latitude/longitude.
• CellIndex
  Represents a cell (hexagon or pentagon) in the H3 grid system at a particular resolution.
• CoordIJ
  IJ hexagon coordinates.
• DirectedEdgeIndex
  Represents a single directed edge between two cells (an “origin” cell and a neighboring “destination” cell).
• Edge
  Edge of an H3 cell.
• Face
  An icosahedron face.
• FaceSet
  A set of icosahedron faces.
• LatLng
  Latitude/longitude.
• LocalIJ
  IJ coordinates anchored by an origin.
• Vertex
  Vertex of an H3 cell.
• VertexIndex
  Represents a single topological vertex in H3 grid system, shared by three cells.

Enums

• Direction
  A direction within an hexagonal grid.
• IndexMode
  H3 index modes.
• Resolution
  Cell resolution, from 0 to 15.

Constants

• EARTH_RADIUS_KM
  Earth radius in kilometers using WGS84 authalic radius.

Functions

• max_grid_disk_size
  Maximum number of indices produced by the grid disk algorithm with the given k.