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Table of Contents generated with DocToc

API Reference

Base type

An unsigned 64-bit integer representing any H3 object (hexagon, pentagon, directed edge ...) represented as a (or 16-character) hexadecimal string, like '8928308280fffff'.

Indexing functions

These function are used for finding the H3 index containing coordinates, and for finding the center and boundary of H3 indexes.

h3_lat_lng_to_cell(latlng point, resolution integer) ⇒ h3index

Since v4.0.0

Indexes the location at the specified resolution.

h3_cell_to_lat_lng(cell h3index) ⇒ point

Since v4.0.0

Finds the centroid of the index.

h3_cell_to_boundary(cell h3index) ⇒ polygon

Since v4.0.0

Finds the boundary of the index.

Use SET h3.extend_antimeridian TO true to extend coordinates when crossing 180th meridian.

Index inspection functions

These functions provide metadata about an H3 index, such as its resolution or base cell, and provide utilities for converting into and out of the 64-bit representation of an H3 index.

h3_get_resolution(h3index) ⇒ integer

Since v1.0.0

Returns the resolution of the index.

h3_get_base_cell_number(h3index) ⇒ integer

Since v4.0.0

Returns the base cell number of the index.

h3_is_valid_cell(h3index) ⇒ boolean

Since v1.0.0

Returns true if the given H3Index is valid.

h3_is_res_class_iii(h3index) ⇒ boolean

Since v1.0.0

Returns true if this index has a resolution with Class III orientation.

h3_is_pentagon(h3index) ⇒ boolean

Since v1.0.0

Returns true if this index represents a pentagonal cell.

h3_get_icosahedron_faces(h3index) ⇒ integer

Since v4.0.0

Find all icosahedron faces intersected by a given H3 index.

Grid traversal functions

Grid traversal allows finding cells in the vicinity of an origin cell, and determining how to traverse the grid from one cell to another.

h3_grid_disk(origin h3index, [k integer = 1]) ⇒ h3index

Since v4.0.0

Produces indices within "k" distance of the origin index.

h3_grid_disk_distances(origin h3index, [k integer = 1], index h3index, distance int) ⇒ record

Since v4.0.0

Produces indices within "k" distance of the origin index paired with their distance to the origin.

h3_grid_ring_unsafe(origin h3index, [k integer = 1]) ⇒ h3index

Since v4.0.0

Returns the hollow hexagonal ring centered at origin with distance "k".

h3_grid_path_cells(origin h3index, destination h3index) ⇒ h3index

Since v4.0.0

Given two H3 indexes, return the line of indexes between them (inclusive).

This function may fail to find the line between two indexes, for example if they are very far apart. It may also fail when finding distances for indexes on opposite sides of a pentagon.

h3_grid_distance(origin h3index, destination h3index) ⇒ bigint

Since v4.0.0

Returns the distance in grid cells between the two indices.

h3_cell_to_local_ij(origin h3index, index h3index) ⇒ point

Since v0.2.0

Produces local IJ coordinates for an H3 index anchored by an origin.

h3_local_ij_to_cell(origin h3index, coord point) ⇒ h3index

Since v0.2.0

Produces an H3 index from local IJ coordinates anchored by an origin.

Hierarchical grid functions

These functions permit moving between resolutions in the H3 grid system. The functions produce parent (coarser) or children (finer) cells.

h3_cell_to_parent(cell h3index, resolution integer) ⇒ h3index

Since v4.0.0

Returns the parent of the given index.

h3_cell_to_children(cell h3index, resolution integer) ⇒ h3index

Since v4.0.0

Returns the set of children of the given index.

h3_cell_to_center_child(cell h3index, resolution integer) ⇒ h3index

Since v4.0.0

Returns the center child (finer) index contained by input index at given resolution.

h3_compact_cells(cells h3index) ⇒ h3index

Since v4.0.0

Compacts the given array as best as possible.

h3_uncompact_cells(cells h3index, resolution integer) ⇒ h3index

Since v4.0.0

Uncompacts the given array at the given resolution.

h3_cell_to_parent(cell h3index) ⇒ h3index

Since v4.0.0

Returns the parent of the given index.

h3_cell_to_children(cell h3index) ⇒ h3index

Since v4.0.0

Returns the set of children of the given index.

h3_cell_to_center_child(cell h3index) ⇒ h3index

Since v4.0.0

Returns the center child (finer) index contained by input index at next resolution.

h3_uncompact_cells(cells h3index) ⇒ h3index

Since v4.0.0

Uncompacts the given array at the resolution one higher than the highest resolution in the set.

h3_cell_to_children_slow(index h3index, resolution integer) ⇒ h3index

Since v4.0.0

Slower version of H3ToChildren but allocates less memory.

h3_cell_to_children_slow(index h3index) ⇒ h3index

Slower version of H3ToChildren but allocates less memory.

Region functions

These functions convert H3 indexes to and from polygonal areas.

h3_polygon_to_cells(exterior polygon, holes polygon, [resolution integer = 1]) ⇒ h3index

Since v4.0.0

Takes an exterior polygon [and a set of hole polygon] and returns the set of hexagons that best fit the structure.

h3_cells_to_multi_polygon(h3index, exterior polygon, holes polygon) ⇒ record

Since v4.0.0

Create a LinkedGeoPolygon describing the outline(s) of a set of hexagons. Polygon outlines will follow GeoJSON MultiPolygon order: Each polygon will have one outer loop, which is first in the list, followed by any holes.

Unidirectional edge functions

Unidirectional edges allow encoding the directed edge from one cell to a neighboring cell.

h3_are_neighbor_cells(origin h3index, destination h3index) ⇒ boolean

Since v4.0.0

Returns true if the given indices are neighbors.

h3_cells_to_directed_edge(origin h3index, destination h3index) ⇒ h3index

Since v4.0.0

Returns a unidirectional edge H3 index based on the provided origin and destination.

h3_is_valid_directed_edge(edge h3index) ⇒ boolean

Since v4.0.0

Returns true if the given edge is valid.

h3_get_directed_edge_origin(edge h3index) ⇒ h3index

Since v4.0.0

Returns the origin index from the given edge.

h3_get_directed_edge_destination(edge h3index) ⇒ h3index

Since v4.0.0

Returns the destination index from the given edge.

h3_directed_edge_to_cells(edge h3index, origin h3index, destination h3index) ⇒ record

Since v4.0.0

Returns the pair of indices from the given edge.

h3_origin_to_directed_edges(h3index) ⇒ h3index

Since v4.0.0

Returns all unidirectional edges with the given index as origin.

h3_directed_edge_to_boundary(edge h3index) ⇒ polygon

Since v4.0.0

Provides the coordinates defining the unidirectional edge.

H3 Vertex functions

Functions for working with cell vertexes.

h3_cell_to_vertex(cell h3index, vertexNum integer) ⇒ h3index

Since v4.0.0

Returns a single vertex for a given cell, as an H3 index.

h3_cell_to_vertexes(cell h3index) ⇒ h3index

Since v4.0.0

Returns all vertexes for a given cell, as H3 indexes.

h3_vertex_to_lat_lng(vertex h3index) ⇒ point

Since v4.0.0

Get the geocoordinates of an H3 vertex.

h3_is_valid_vertex(vertex h3index) ⇒ boolean

Since v4.0.0

Whether the input is a valid H3 vertex.

Miscellaneous H3 functions

These functions include descriptions of the H3 grid system.

h3_great_circle_distance(a point, b point, [unit text = km]) ⇒ double

Since v4.0.0

The great circle distance in radians between two spherical coordinates.

h3_get_hexagon_area_avg(resolution integer, [unit text = km]) ⇒ double

Since v4.0.0

Average hexagon area in square (kilo)meters at the given resolution.

h3_cell_area(cell h3index, [unit text = km^2]) ⇒ double

Since v4.0.0

Exact area for a specific cell (hexagon or pentagon).

h3_get_hexagon_edge_length_avg(resolution integer, [unit text = km]) ⇒ double

Since v4.0.0

Average hexagon edge length in (kilo)meters at the given resolution.

h3_edge_length(edge h3index, [unit text = km]) ⇒ double

Since v4.0.0

Exact length for a specific unidirectional edge.

h3_get_num_cells(resolution integer) ⇒ bigint

Since v4.0.0

Number of unique H3 indexes at the given resolution.

h3_get_res_0_cells() ⇒ h3index

Since v4.0.0

Returns all 122 resolution 0 indexes.

h3_get_pentagons(resolution integer) ⇒ h3index

Since v4.0.0

All the pentagon H3 indexes at the specified resolution.

Operators

B-tree operators

Operator: h3index = h3index

Since v0.1.0

Returns true if two indexes are the same.

Operator: h3index <> h3index

Since v0.1.0

R-tree Operators

Operator: h3index && h3index

Since v3.6.1

Returns true if the two H3 indexes intersect.

Operator: h3index @> h3index

Since v3.6.1

Returns true if A containts B.

Operator: h3index <@ h3index

Since v3.6.1

Returns true if A is contained by B.

Operator: h3index <-> h3index

Since v3.7.0

Returns the distance in grid cells between the two indices.

Type casts

h3index :: bigint

Convert H3 index to bigint, which is useful when you need a decimal representation.

bigint :: h3index

Convert bigint to H3 index.

h3index :: point

Convert H3 index to point.

Extension specific functions

h3_get_extension_version() ⇒ text

Since v1.0.0

Get the currently installed version of the extension.

WKB indexing functions

h3_cell_to_boundary_wkb(cell h3index) ⇒ bytea

Since v4.0.1

Finds the boundary of the index, converts to EWKB.

Splits polygons when crossing 180th meridian.

This function has to return WKB since Postgres does not provide multipolygon type.

Deprecated functions

h3_cell_to_boundary(cell h3index, extend_antimeridian boolean) ⇒ polygon

DEPRECATED: Use SET h3.extend_antimeridian TO true instead.