File: lib/Geo/H3.pm

NAME

Geo::H3 - H3 Geospatial Hexagon Indexing System

SYNOPSIS

use Geo::H3;
my $gh3      = Geo::H3->new;

my $hex      = $gh3->h3(uint64 => $int);        #isa Geo::H3::Index
my $hex      = $gh3->h3(string => $string);     #isa Geo::H3::Index

my $geo      = $gh3->geo(lat=>$lat, lon=>$lon); #isa Geo::H3::Geo
my $hex      = $geo->h3($resolution);           #isa Geo::H3::Index

my $center   = $h3->center;                     #isa Geo::H3::GeoCoord
my $lat      = $center->lat;                    #isa Double WGS-84 Decimal Degrees
my $lon      = $center->lon;                    #isa Double WGS-84 Decimal Degrees
my $distance = $center->distance($geo);         #isa Double meters

DESCRIPTION

This Perl distribution provides a Perl Object Oriented interface to the H3 Core Library. It accesses the H3 C library using libffi and FFI::Platypus.

H3 is a geospatial indexing system that partitions the world into hexagonal cells. Please note that a very few number of cells are pentagons but we use the terms hex or hexagon to include pentagons.

The H3 Core Library implements the H3 grid system. It includes functions for converting from latitude and longitude coordinates to the containing H3 cell, finding the center of H3 cells, finding the boundary geometry of H3 cells, finding neighbors of H3 cells, and more.

The H3 Core Library can be installed from Uber's H3 repository on GitHub https://github.com/uber/h3 which is well documented at https://h3geo.org/docs/.

CONVENTIONS

The Geo::H3 lib is an Object Oriented wrapper on top of the Geo::H3::FFI library. Geo::H3 was written as a wrapper so that in the future we are able to re-write against different backends such as the yet to be developed Geo::H3::XS backend.

libh3

- Latitude and longitude cordinates are in radians WGS-84
- H3 Index values are handled as uint64 integers
- GeoCoord values are handled as C structures with lat and lon
- GeoBoundary values are handled as C structures with num_verts and verts

Geo::H3::FFI

- Latitude and Longitude cordinates are in radians WGS-84
- H3 Index values are handled as uint64 integers
- GeoCoord values are handled as Geo::H3::FFI::Struct::GeoCoord objects
- GeoBoundary values are handled as Geo::H3::FFI::Struct::GeoBoundary objects

Geo::H3

- Latitude and longitue cordinates are in decimal degrees WGS-84
- H3 Index values are handled as Geo::H3::Index objects
- GeoCoord values are handled as Geo::H3::GeoCoord objects
- GeoBoundary values are handled as Geo::H3::GeoBoundary objects

CONSTRUCTORS

h3

Returns a Geo::H3::Index object

my $hex = $gh3->h3(unit64 => $int);                  #isa Geo::H3::Index
my $hex = $gh3->h3(string => $string);               #isa Geo::H3::Index
my $hex = Geo::H3::Index->new(uint64 => $h3_uint64); #isa Geo::H3::Index
my $hex = Geo::H3::Index->new(string => $h3_string); #isa Geo::H3::Index

geo

Returns a Geo::H3::Geo object

my $geo = $gh3->geo(lat=>$lat_deg, lon=>$lon_deg);         #isa Geo::H3::Geo
my $geo = Geo::H3::Geo->new(lat=>$lat_deg, lon=>$lon_deg); #isa Geo::H3::Geo

ffi

Returns the Geo::H3::FFI object.

LIMITATIONS

This package uses the naming convention of version 3.x of the Uber H3 library. The organization that maintains the open source Uber H3 library has not maintained backward compatibility in version 4.x. This Perl distribution currently sees no reason to support the 4.x version of the Uber H3 library as the 3.7.2 release is stable and full featured.

AUTHOR

Michael R. Davis

COPYRIGHT AND LICENSE

MIT License

File: lib/Geo/H3/Index.pm

NAME

Geo::H3::Index - H3 Geospatial Hexagon Indexing System Index Object

SYNOPSIS

use Geo::H3::Index;
my $h3       = Geo::H3::Index->new(string => $string); #isa Geo::H3::Index
my $center   = $h3->geo;                             #isa Geo::H3::Geo
my $lat      = $center->lat;                         #isa double WGS-84 Decimal Degrees
my $lon      = $center->lon;                         #isa double WGS-84 Decimal Degrees
my $boundary = $h3->geoBoundary;                     #isa Geo::H3::GeoBoundary

DESCRIPTION

H3 Geospatial Hexagon Indexing System Index Object provides the primary interface for working with H3 Indexes.

CONSTRUCTORS

new

my $h3 = Geo::H3::Index->new(string=>$string);
my $h3 = Geo::H3::Index->new(uint64=>$uint64);

PROPERTIES

string

Returns the H3 string representation.

uint64

Returns the H3 uint64 representation.

index (DEPRECATED)

Returns the H3 uint64 representation.

Please note that `index()` was difficult to remember consistently. Therefore, I plan to move to the `uint64()` property moving forward while maintaining backwards compatibility.

resolution

Returns the resolution of the hex.

baseCell

Returns the base cell number of the hex.

isValid

Returns non-zero if this is a valid H3 hex.

isResClassIII

Returns non-zero if this hex has a resolution with Class III orientation.

isPentagon

Returns non-zero if this hex represents a pentagonal cell.

maxFaceCount

Returns the maximum number of icosahedron faces the given H3 hex may intersect.

area

Returns the area in square meters of this hex.

areaApprox

Returns the average area in square meters of hexes at this resolution.

edgeLength

Returns the exact edge length in meters that this hex shares with the passed in neighbor.

my $edgeLength_meters = $hex->edgeLength(); #default hex is first kring neighbor
my $edgeLength_meters = $hex->edgeLength($neighbor_hex_obj);

edgeLengthAverage

Returns the average of the exact edge lengths in meters of this hex.

edgeLengthApprox

Returns the average edge length in meters of hexes at this resolution.

METHODS

geo

Returns the centroid of the hex as a Geo::H3::Geo object.

geoBoundary

Returns the boundary of the hex as a Geo::H3::GeoBoundary object

parent

Returns a parent hex of this hex as a Geo::H3::Index object.

my $parent = $h3->parent;    #next larger resolution
my $parent = $h3->parent(1); #isa Geo::H3::Index

children

Returns the children of the hex as an array reference of Geo::H3::Index objects.

my $children = $h3->children(12); #isa ARRAY
my $children = $h3->children;     #next smaller resolution

centerChild

Returns the center child (finer) hex contained by this hex at given resolution.

my $centerChild = $hex->centerChild;      #isa Geo::H3::Index
my $centerChild = $hex->centerChild(12);  #isa Geo::H3::Index

kRing

Returns k-rings hexes within k distance of the origin hex.

my $hexes_aref = $hex->kRing($k); #isa ARRAY of L<Geo::H3::Index> objects

kRingDistances

Returns a hash reference where the keys are the H3 hex and values are the k distance for the given hex and k value.

my $distances_aref = $hex->kRingDistances($k); #isa ARRAY-ARRAY [ [$hex1, $dist1], [$hex2, $dist2], ... [$hexN, $distN] ]

hexRange

Returns an array reference of hexes within k distance of the hex object. k-ring 0 is defined as the origin index, k-ring 1 is defined as k-ring 0 and all neighboring indexes, and so on.

my $hexes_aref = $hex->hexRange($k);

hexRangeDistances

Returns a hash reference where the keys are the H3 uint64 and values are the k distance for the given hex and k value.

my $hash = $hex->hexRangeDistances($k); #isa ARRAY-ARRAY [ [$hex1, $dist1], [$hex2, $dist2], ... [$hexN, $distN] ]

hexRing

Returns the hex ring of this hex as an array reference of Geo::H3::Index objects

my $hexes = $h3->hexRing; #default k = 1
my $hexes = $h3->hexRing(5); #isa ARRAY

areNeighbors

Returns a 1 or 0 based on whether or not the provided hex object is a neighbor.

my $areNeighbors = $start_hex->areNeighbors($end_hex);

line

Returns the hexes starting at this hex to the given end hex as array reference of Geo::H3::Index objects.

my $list_aref = $start_hex_obj->line($end_hex_obj);

distance

Returns the distance in grid cells between this hex to the given end hex.

my $distance = $start_hex_obj->distance($end_hex_obj);

AUTHOR

Michael R. Davis

COPYRIGHT AND LICENSE

MIT License

File: lib/Geo/H3/Geo.pm

NAME

Geo::H3::Geo - H3 Geospatial Hexagon Indexing System Geo Object

SYNOPSIS

use Geo::H3::Geo;
my $geo    = Geo::H3::Geo->new(lat=>$lat, lon=>$lon); #isa Geo::H3::Geo
my $h3     = $geo->h3($resolution);                   #isa Geo::H3::Index
my $center = $h3->geo;                                #isa Geo::H3::Geo
my $lat    = $center->lat;                            #isa double WGS-84 Decimal Degrees
my $lon    = $center->lon;                            #isa double WGS-84 Decimal Degrees

DESCRIPTION

H3 Geospatial Hexagon Indexing System Geo Object exposes the lat and lon properties as WGS-84 Decimal Degrees and converts coordinates to radians in the struct method for passing into theGeo::H3::FFI API as a Geo::H3::FFI::Struct::GeoCoord object.

The methods h3 and distance are wrappers around select Geo::H3::FFI methods.

CONSTRUCTORS

new

my $geo = Geo::H3::Geo->new(lat => $lat, lon => $lon);

PROPERTIES

lat

Returns the latitude in decimal degrees WGS-84

lon

Returns the longitude in decimal degrees WGS-84

METHODS

struct

Returns the Geo object as an FFI::C struct in the Geo::H3::FFI::Struct::GeoCoord namespace for use in the Geo::H3::FFI API.

h3

Indexes the location at the specified resolution, returning the hex object Geo::H3::Index of the cell containing the location.

my $h3 = $geo->h3;    #default resolution is 0
my $h3 = $geo->h3(7); #isa Geo::H3::H3Index

Returns undef on error.

distance

Returns in meters the "great circle" or "haversine" distance between pairs of points (lat/lon pairs).

my $distance = $geoA->distance($geoB); #isa Double

AUTHOR

Michael R. Davis

COPYRIGHT AND LICENSE

MIT License

File: lib/Geo/H3/GeoBoundary.pm

NAME

Geo::H3::GeoBoundary - H3 Geospatial Hexagon Indexing System GeoBoundary Object

SYNOPSIS

use Geo::H3::GeoBoundary;
my $GeoBoundary = Geo::H3::GeoBoundary->new(gb=>$gb);            #isa Geo::H3::GeoBoundary
my $GeoBoundary = Geo::H3::GeoBoundary->new(gb=>$gb, ffi=>$ffi); #isa Geo::H3::GeoBoundary

DESCRIPTION

H3 Geospatial Hexagon Indexing System GeoBoundary Object provides coordinates method to extract data from the FFI GeoBoundary object

CONSTRUCTORS

new

my $GeoBoundary = Geo::H3::GeoBoundary->new(gb=>$gb);

PROPERTIES

gb

Returns the H3 GeoBoundary Object from the API as a Geo::H3::FFI::Struct::GeoBoundary object

my $struct = $GeoBoundary->gb; #isa Geo::H3::FFI::Struct::GeoBoundary

METHODS

coordinates

Returns an OGC compatible closed polygon as an array reference of hashes i.e. [{lat=>$lat, lon=>$lon}, ...].

This coordinates format plugs directly into the format required for many Geo::GoogleEarth::Pluggable objects.

AUTHOR

Michael R. Davis

COPYRIGHT AND LICENSE

MIT License

File: scripts/perl-Geo-H3-geo-to-googleearth.pl

NAME

perl-Geo-H3-geo-to-googleearth.pl - Creates a Google Earth document from Coordinates, H3, Parent, Children and Hex Ring.

SYNTAX

perl-Geo-H3-geo-to-googleearth.pl --lat=[degrees] --lon=[degrees] --resolution=[hex_resolution] --output=[output_filename]

EXAMPLES

Default creates output.kmz

$ perl-Geo-H3-geo-to-googleearth.pl
Lat: 38.8894806546995
Lon: -77.0352387595358
Resolution: 8
Output: output.kmz
Format: kmz

KMZ output with defaults specified

$ perl-Geo-H3-geo-to-googleearth.pl --lat=38.889480654699476 --lon=-77.03523875953579 --resolution=8 --output=output.kmz
Lat: 38.889480654699476
Lon: -77.03523875953579
Resolution: 8
Output: output.kmz
Format: kmz

KML output pass a file name with "kml" extension.

$ perl-Geo-H3-geo-to-googleearth.pl --output=output.kml
Lat: 38.8894806546995
Lon: -77.0352387595358
Resolution: 8
Output: output.kml
Format: kml

COPYRIGHT AND LICENSE

MIT License

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File: lib/Geo/H3.pm

NAME

SYNOPSIS

DESCRIPTION

CONVENTIONS

libh3

Geo::H3::FFI

Geo::H3

CONSTRUCTORS

h3

geo

ffi

LIMITATIONS

SEE ALSO

AUTHOR

COPYRIGHT AND LICENSE

File: lib/Geo/H3/Index.pm

NAME

SYNOPSIS

DESCRIPTION

CONSTRUCTORS

new

PROPERTIES

string

uint64

index (DEPRECATED)

resolution

baseCell

isValid

isResClassIII

isPentagon

maxFaceCount

area

areaApprox

edgeLength

edgeLengthAverage

edgeLengthApprox

METHODS

geo

geoBoundary

parent

children

centerChild

kRing

kRingDistances

hexRange

hexRangeDistances

hexRing

areNeighbors

line

distance

SEE ALSO

AUTHOR

COPYRIGHT AND LICENSE

File: lib/Geo/H3/Geo.pm

NAME

SYNOPSIS

DESCRIPTION

CONSTRUCTORS

new

PROPERTIES

lat

lon

METHODS

struct

h3

distance

SEE ALSO

AUTHOR

COPYRIGHT AND LICENSE

File: lib/Geo/H3/GeoBoundary.pm

NAME

SYNOPSIS

DESCRIPTION

CONSTRUCTORS

new

PROPERTIES

gb

METHODS

coordinates