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Man Pages


Manual Reference Pages  -  GEO::JSON (3)

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NAME

Geo::JSON - Perl OO interface for geojson

CONTENTS

SYNOPSIS



    use Geo::JSON;
   
    my $obj = Geo::JSON->from_json( $json );
   
    $obj->to_json();



DESCRIPTION

Convert to and from geojson using Perl objects. GeoJSON objects represent various geographical positions - points, lines, polygons, etc.

Currently supports 2 or 3 dimensions (longitude, latitude, altitude). Further dimensions in positions are ignored for calculations and comparisons, but will be read-from and written-to.

GEOJSON SPECIFICATION

See: <http://www.geojson.org/geojson-spec.html>

GEOJSON MEMBERS (ATTRIBUTES)

See the specification for the full details, but the basics are as follows:
o type

Determines the object the json will be turned into

o position

Not explicitly named in the json, but an array of at least two numbers representing a location in x, y, z order (either Easting, Northing, Altitude or Longitude, Latitude, Altitude as appropriate).

Additional numbers may be present but ignored by this package for calculations.

o coordinates

Defined in geometry objects (Point, MultiPoint, LineString, MultiLineString, Polygon, MultiPolygon). Will consist of a single position (Point), an array of positions (MultiPoint, LineString), an array of arrays of positions (MultiLineString, Polygon) or an array of arrays of arrays of positions (MultiPolygon). The positions within a single object should all have the same number of axes and be in the same axis order.

o bbox

Optional, defining a bounding box that the position(s) are contained by.

The box is defined by a array of 2*n items, where n is the number of dimensions in a position. The items are the lowest value for an axis followed by the highest value for an axis, in the axis order used in the positions.

The Co-ordinates Reference System for the bounding box is assumed to match that of the object.

o crs

Optional, defining the Co-ordinates Reference System the object is using. See Geo::JSON::CRS for more details.

GEOMETRY OBJECTS

o Geo::JSON::Point

A single position

o Geo::JSON::MultiPoint

An array of positions, representing multiple points

o Geo::JSON::LineString

An array of 2 or more positions, represening a connected line

o Geo::JSON::MultiLineString

An array of lines

o Geo::JSON::Polygon

An array of lines, defining a polygon. The first line represents the outside of the polygon, subsequent lines define any ’holes’. The lines must be ’linear rings’ - 4 or more points, with the first and last points being equivalent.

o Geo::JSON::MultiPolygon

An array of polygons

o Geo::JSON::GeometryCollection

An array of any of the above Geometry objects (as attribute geometries)

FEATURE OBJECTS

o Geo::JSON::Feature

Any of the above objects (as attribute feature), together with a data structure (as attruibute properties)

FEATURE COLLECTION OBJECTS

o Geo::JSON::FeatureCollection

An array of Feature objects (as attribute features)

METHODS

    from_json



    my $obj = Geo::JSON->from_json( $json );



Takes a geojson string, returns the object it represents.

    to_json



    $obj->to_json();
    $obj->to_json( $codec );



Call on a Geo::JSON object. Returns the JSON that represents the object.

Pass in an optional JSON codec to modify the default behaviour of the JSON returned.

    load



    my $obj = Geo::JSON->load( { type => Point, coordinates => ... } );



Creates a Geo::JSON object from a hashref.

This is used for coercion of attributes during object creation, and probably should not be called directly otherwise.

CLASS METHODS

    codec



    Geo::JSON->codec->canonical(1)->pretty;
   
    my $prev_codec = Geo::JSON->codec($new_codec);



Set options on or replace JSON codec.

THANKS

Tim Bunce - for codec suggestions and bug spotting.

SEE ALSO

o Geo::JSON::Simple - simple interface to create Geo::JSON objects.

SUPPORT

    Bugs / Feature Requests

Please report any bugs or feature requests through the issue tracker at <https://github.com/mjemmeson/Geo-JSON/issues>. You will be notified automatically of any progress on your issue.

    Source Code

This is open source software. The code repository is available for public review and contribution under the terms of the license.

<https://github.com/mjemmeson/Geo-JSON>



  git clone https://github.com/mjemmeson/Geo-JSON.git



AUTHOR

Michael Jemmeson <mjemmeson@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2015 by Michael Jemmeson <mjemmeson@cpan.org>.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

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perl v5.20.3 GEO::JSON (3) 2015-02-16

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