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.. index:: single: geohash_protocol .. _geohash_protocol/0:
.. rst-class:: right
protocol
geohash_protocol
Geohash predicates protocol.
| Availability:
| logtalk_load(geohash(loader))
| Author: Paulo Moura | Version: 1:2:0 | Date: 2026-05-11
| Compilation flags:
| static
| Dependencies: | (none)
| Remarks: | (none)
| Inherited public predicates: | (none)
.. contents:: :local: :backlinks: top
Public predicates
.. index:: valid_geohash/1 .. _geohash_protocol/0::valid_geohash/1:
valid_geohash/1 ^^^^^^^^^^^^^^^^^^^
True when the argument is a non-empty geohash atom using the standard geohash base-32 alphabet 0123456789bcdefghjkmnpqrstuvwxyz.
| Compilation flags:
| static
| Template:
| valid_geohash(Geohash)
| Mode and number of proofs:
| valid_geohash(+atom) - zero_or_one
.. index:: encode/3 .. _geohash_protocol/0::encode/3:
encode/3 ^^^^^^^^^^^^
Encodes a geographic coordinate represented as geographic(Latitude,Longitude) into a geohash atom with the given precision in characters. Longitude is canonicalized to the [-180.0,180.0[ range, so 180.0 is treated as -180.0.
| Compilation flags:
| static
| Template:
| encode(Coordinate,Precision,Geohash)
| Mode and number of proofs:
| encode(+compound,+positive_integer,-atom) - zero_or_one
.. index:: decode/2 .. _geohash_protocol/0::decode/2:
decode/2 ^^^^^^^^^^^^
Decodes a geohash atom into the center geographic coordinate of the represented cell.
| Compilation flags:
| static
| Template:
| decode(Geohash,Coordinate)
| Mode and number of proofs:
| decode(+atom,-compound) - zero_or_one
.. index:: bounding_box/2 .. _geohash_protocol/0::bounding_box/2:
bounding_box/2 ^^^^^^^^^^^^^^^^^^
Decodes a geohash atom into its geographic bounding box represented as bbox(geographic(MinLatitude,MinLongitude),geographic(MaxLatitude,MaxLongitude)).
| Compilation flags:
| static
| Template:
| bounding_box(Geohash,BoundingBox)
| Mode and number of proofs:
| bounding_box(+atom,-compound) - zero_or_one
.. index:: precision/3 .. _geohash_protocol/0::precision/3:
precision/3 ^^^^^^^^^^^^^^^
Returns the maximum latitude and longitude errors in degrees for geohashes of the given precision in characters.
| Compilation flags:
| static
| Template:
| precision(Precision,LatitudeError,LongitudeError)
| Mode and number of proofs:
| precision(+positive_integer,-float,-float) - zero_or_one
.. index:: cell_dimensions/3 .. _geohash_protocol/0::cell_dimensions/3:
cell_dimensions/3 ^^^^^^^^^^^^^^^^^^^^^
Returns the latitude and longitude spans in degrees of a geohash cell for the given precision in characters.
| Compilation flags:
| static
| Template:
| cell_dimensions(Precision,LatitudeSpan,LongitudeSpan)
| Mode and number of proofs:
| cell_dimensions(+positive_integer,-float,-float) - zero_or_one
.. index:: adjacent/3 .. _geohash_protocol/0::adjacent/3:
adjacent/3 ^^^^^^^^^^^^^^
Returns the adjacent geohash in the given direction. Supported directions are north, south, east, west, north_east, north_west, south_east, and south_west. Eastward and westward adjacency wraps across the antimeridian using the same longitude canonicalization as encode/3. Northward and southward adjacency fails when there is no neighboring cell beyond the poles.
| Compilation flags:
| static
| Template:
| adjacent(Geohash,Direction,AdjacentGeohash)
| Mode and number of proofs:
| adjacent(+atom,+atom,-atom) - zero_or_one
.. index:: neighbors/2 .. _geohash_protocol/0::neighbors/2:
neighbors/2 ^^^^^^^^^^^^^^^
Returns the available neighboring geohashes as Direction-Geohash pairs in clockwise order starting at north.
| Compilation flags:
| static
| Template:
| neighbors(Geohash,Neighbors)
| Mode and number of proofs:
| neighbors(+atom,-list(compound)) - zero_or_one
.. index:: covering/3 .. _geohash_protocol/0::covering/3:
covering/3 ^^^^^^^^^^^^^^
Returns the list of geohashes at the given precision whose cells cover a geographic bounding box represented as bbox(geographic(MinLatitude,MinLongitude),geographic(MaxLatitude,MaxLongitude)). Degenerate point bounding boxes and exact cell-aligned boundaries are accepted. Antimeridian-crossing bounding boxes are accepted.
| Compilation flags:
| static
| Template:
| covering(BoundingBox,Precision,Geohashes)
| Mode and number of proofs:
| covering(+compound,+positive_integer,-list(atom)) - zero_or_one
.. index:: covering/4 .. _geohash_protocol/0::covering/4:
covering/4 ^^^^^^^^^^^^^^
Returns a geohash cover for a geographic bounding box. CoverSpec is either precision(Precision) for a fixed-depth cover or max_precision(MaxPrecision) for an adaptive mixed-depth cover. Options may include compact(Boolean) and min_precision(PositiveInteger).
| Compilation flags:
| static
| Template:
| covering(BoundingBox,CoverSpec,Geohashes,Options)
| Mode and number of proofs:
| covering(+compound,+compound,-list(atom),++list(compound)) - zero_or_one
.. index:: compress/2 .. _geohash_protocol/0::compress/2:
compress/2 ^^^^^^^^^^^^^^
Compresses a list of geohashes by replacing complete sibling sets with their parent prefix while preserving the covered area.
| Compilation flags:
| static
| Template:
| compress(Geohashes,CompressedGeohashes)
| Mode and number of proofs:
| compress(+list(atom),-list(atom)) - zero_or_one
.. index:: parent/2 .. _geohash_protocol/0::parent/2:
parent/2 ^^^^^^^^^^^^
Returns the immediate parent prefix of a geohash. Fails for precision-1 geohashes.
| Compilation flags:
| static
| Template:
| parent(Geohash,Parent)
| Mode and number of proofs:
| parent(+atom,-atom) - zero_or_one
.. index:: children/2 .. _geohash_protocol/0::children/2:
children/2 ^^^^^^^^^^^^^^
Returns the 32 child geohashes of a geohash in standard geohash base-32 order.
| Compilation flags:
| static
| Template:
| children(Geohash,Children)
| Mode and number of proofs:
| children(+atom,-list(atom)) - zero_or_one
.. index:: common_prefix/3 .. _geohash_protocol/0::common_prefix/3:
common_prefix/3 ^^^^^^^^^^^^^^^^^^^
Returns the longest common geohash prefix shared by two geohashes. The prefix may be the empty atom when the geohashes share no leading characters.
| Compilation flags:
| static
| Template:
| common_prefix(Geohash1,Geohash2,Prefix)
| Mode and number of proofs:
| common_prefix(+atom,+atom,-atom) - zero_or_one
.. index:: encode_int/3 .. _geohash_protocol/0::encode_int/3:
encode_int/3 ^^^^^^^^^^^^^^^^
Encodes a geographic coordinate into an integer geohash representation at the given precision in characters.
| Compilation flags:
| static
| Template:
| encode_int(Coordinate,Precision,HashInteger)
| Mode and number of proofs:
| encode_int(+compound,+positive_integer,-integer) - zero_or_one
.. index:: decode_int/3 .. _geohash_protocol/0::decode_int/3:
decode_int/3 ^^^^^^^^^^^^^^^^
Decodes an integer geohash representation at the given precision into the center geographic coordinate of the represented cell.
| Compilation flags:
| static
| Template:
| decode_int(HashInteger,Precision,Coordinate)
| Mode and number of proofs:
| decode_int(+integer,+positive_integer,-compound) - zero_or_one
.. index:: bounding_box_int/3 .. _geohash_protocol/0::bounding_box_int/3:
bounding_box_int/3 ^^^^^^^^^^^^^^^^^^^^^^
Decodes an integer geohash representation at the given precision into its geographic bounding box.
| Compilation flags:
| static
| Template:
| bounding_box_int(HashInteger,Precision,BoundingBox)
| Mode and number of proofs:
| bounding_box_int(+integer,+positive_integer,-compound) - zero_or_one
.. index:: adjacent_int/4 .. _geohash_protocol/0::adjacent_int/4:
adjacent_int/4 ^^^^^^^^^^^^^^^^^^
Returns the adjacent integer geohash at the same precision in the given direction.
| Compilation flags:
| static
| Template:
| adjacent_int(HashInteger,Precision,Direction,AdjacentHashInteger)
| Mode and number of proofs:
| adjacent_int(+integer,+positive_integer,+atom,-integer) - zero_or_one
.. index:: neighbors_int/3 .. _geohash_protocol/0::neighbors_int/3:
neighbors_int/3 ^^^^^^^^^^^^^^^^^^^
Returns the available neighboring integer geohashes as Direction-HashInteger pairs in clockwise order starting at north.
| Compilation flags:
| static
| Template:
| neighbors_int(HashInteger,Precision,Neighbors)
| Mode and number of proofs:
| neighbors_int(+integer,+positive_integer,-list(compound)) - zero_or_one
.. index:: geohash_to_int/2 .. _geohash_protocol/0::geohash_to_int/2:
geohash_to_int/2 ^^^^^^^^^^^^^^^^^^^^
Converts a geohash atom to its packed integer representation using five bits per character.
| Compilation flags:
| static
| Template:
| geohash_to_int(Geohash,HashInteger)
| Mode and number of proofs:
| geohash_to_int(+atom,-integer) - zero_or_one
.. index:: int_to_geohash/3 .. _geohash_protocol/0::int_to_geohash/3:
int_to_geohash/3 ^^^^^^^^^^^^^^^^^^^^
Converts a packed integer geohash representation and an explicit precision in characters to a geohash atom.
| Compilation flags:
| static
| Template:
| int_to_geohash(HashInteger,Precision,Geohash)
| Mode and number of proofs:
| int_to_geohash(+integer,+positive_integer,-atom) - zero_or_one
.. index:: encode_bits/3 .. _geohash_protocol/0::encode_bits/3:
encode_bits/3 ^^^^^^^^^^^^^^^^^
Encodes a geographic coordinate into an integer geohash representation using the given bit precision.
| Compilation flags:
| static
| Template:
| encode_bits(Coordinate,Bits,HashInteger)
| Mode and number of proofs:
| encode_bits(+compound,+positive_integer,-integer) - zero_or_one
.. index:: decode_bits/3 .. _geohash_protocol/0::decode_bits/3:
decode_bits/3 ^^^^^^^^^^^^^^^^^
Decodes an integer geohash representation at the given bit precision into the center geographic coordinate of the represented cell.
| Compilation flags:
| static
| Template:
| decode_bits(HashInteger,Bits,Coordinate)
| Mode and number of proofs:
| decode_bits(+integer,+positive_integer,-compound) - zero_or_one
.. index:: bounding_box_bits/3 .. _geohash_protocol/0::bounding_box_bits/3:
bounding_box_bits/3 ^^^^^^^^^^^^^^^^^^^^^^^
Decodes an integer geohash representation at the given bit precision into its geographic bounding box.
| Compilation flags:
| static
| Template:
| bounding_box_bits(HashInteger,Bits,BoundingBox)
| Mode and number of proofs:
| bounding_box_bits(+integer,+positive_integer,-compound) - zero_or_one
.. index:: adjacent_bits/4 .. _geohash_protocol/0::adjacent_bits/4:
adjacent_bits/4 ^^^^^^^^^^^^^^^^^^^
Returns the adjacent integer geohash at the same bit precision in the given direction.
| Compilation flags:
| static
| Template:
| adjacent_bits(HashInteger,Bits,Direction,AdjacentHashInteger)
| Mode and number of proofs:
| adjacent_bits(+integer,+positive_integer,+atom,-integer) - zero_or_one
.. index:: neighbors_bits/3 .. _geohash_protocol/0::neighbors_bits/3:
neighbors_bits/3 ^^^^^^^^^^^^^^^^^^^^
Returns the available neighboring integer geohashes as Direction-HashInteger pairs in clockwise order starting at north for the given bit precision.
| Compilation flags:
| static
| Template:
| neighbors_bits(HashInteger,Bits,Neighbors)
| Mode and number of proofs:
| neighbors_bits(+integer,+positive_integer,-list(compound)) - zero_or_one
.. index:: expand/2 .. _geohash_protocol/0::expand/2:
expand/2 ^^^^^^^^^^^^
Returns the geohash followed by its available neighbors in clockwise order starting at north.
| Compilation flags:
| static
| Template:
| expand(Geohash,ExpandedGeohashes)
| Mode and number of proofs:
| expand(+atom,-list(atom)) - zero_or_one
.. index:: expand_int/3 .. _geohash_protocol/0::expand_int/3:
expand_int/3 ^^^^^^^^^^^^^^^^
Returns the integer geohash followed by its available neighboring integer geohashes in clockwise order starting at north.
| Compilation flags:
| static
| Template:
| expand_int(HashInteger,Precision,ExpandedHashes)
| Mode and number of proofs:
| expand_int(+integer,+positive_integer,-list(integer)) - zero_or_one
.. index:: polygon_covering/4 .. _geohash_protocol/0::polygon_covering/4:
polygon_covering/4 ^^^^^^^^^^^^^^^^^^^^^^
Returns a geohash cover for a polygon represented as a list of geographic coordinates. CoverSpec is either precision(Precision) for a fixed-depth cover or max_precision(MaxPrecision) for an adaptive mixed-depth cover. Options may include compact(Boolean) and min_precision(PositiveInteger). Antimeridian-crossing polygons are not supported.
| Compilation flags:
| static
| Template:
| polygon_covering(Polygon,CoverSpec,Geohashes,Options)
| Mode and number of proofs:
| polygon_covering(+list(compound),+compound,-list(atom),++list(compound)) - zero_or_one
.. index:: polyline_covering/4 .. _geohash_protocol/0::polyline_covering/4:
polyline_covering/4 ^^^^^^^^^^^^^^^^^^^^^^^
Returns a geohash cover for a polyline represented as a list of two or more geographic coordinates. CoverSpec is either precision(Precision) for a fixed-depth cover or max_precision(MaxPrecision) for an adaptive mixed-depth cover. Options may include compact(Boolean), min_precision(PositiveInteger), and buffer(Distance) where the buffer distance is given in kilometers. Antimeridian-crossing polylines are not supported.
| Compilation flags:
| static
| Template:
| polyline_covering(Polyline,CoverSpec,Geohashes,Options)
| Mode and number of proofs:
| polyline_covering(+list(compound),+compound,-list(atom),++list(compound)) - zero_or_one
Protected predicates
(none)
Private predicates
(none)
Operators
(none)
.. seealso::
:ref:`geohash <geohash/0>`, :ref:`geospatial <geospatial/0>`