https://github.com/g-andrade/erlquad

Simple quadtrees
https://github.com/g-andrade/erlquad

erlang quadtree

Last synced: about 4 hours ago
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Simple quadtrees

• Host: GitHub
• URL: https://github.com/g-andrade/erlquad
• Owner: g-andrade
• License: mit
• Archived: true
• Created: 2016-03-31T23:23:36.000Z (almost 9 years ago)
• Default Branch: master
• Last Pushed: 2019-01-19T18:32:34.000Z (about 6 years ago)
• Last Synced: 2024-12-29T13:21:34.301Z (25 days ago)
• Topics: erlang, quadtree
• Language: Erlang
• Homepage:
• Size: 24.4 KB
• Stars: 14
• Watchers: 2
• Forks: 2
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        


# erlquad #

Copyright (c) 2016 Guilherme Andrade

__Version:__ 1.1.2

__Authors:__ Guilherme Andrade ([`erlquad(at)gandrade(dot)net`](mailto:erlquad(at)gandrade(dot)net)).

`erlquad`: A simple Erlang quadtree implementation

---------

`erlquad` is a straightforward Erlang implementation of [quadtrees](https://en.wikipedia.org/wiki/Quadtree), supporting both bounding-box outlines as well as precise coordinates for small enough objects.

It exposes functions for fetching, folding and any'ing (with boolean predicate) particular areas of interest as well as all contained objects. Deeplist versions of fetching methods are also included for when there's no need to concatenate the intermediate results and thus avoid the overhead of doing so.

Buckets have unlimited capacity and depth is fixed on initialization.

```erlang

Object1 = #big_square{ x = 1000, y = 750,  side = 10 },

Object2 = #tiny_circle{ x = 3000, y = 1000 },

Object3 = #tiny_circle{ x = 3000, y = 2000 },

GetOutline = fun (#tiny_circle{ x = X, y = Y }) ->

                    {X, Y};

                 (#big_square{ x = X, y = Y, side = S }) ->

                    {X - S/2, Y - S/2, X + S/2, Y + S/2}

             end,

IsSquare = fun (#tiny_circle{}) -> false;

               (#big_square{})  -> true

           end,

CountCirclesFold = fun (#tiny_circle{}, Acc) -> Acc + 1;

                       (#big_square{}, Acc)  -> Acc

                   end,

Q1 = erlquad:new(0, 0, 4000, 3000, 3), % Left, Bottom, Right, Top, Depth

Q2 = erlquad:objects_add([Object1, Object2, Object3], GetOutline, Q1),

erlquad:area_query(0, 0, 1999, 2999, Q2),       % [#big_square{...}]

erlquad:area_query(2000, 0, 3999, 2999, Q2),    % [#tiny_circle{...}, #tiny_circle{...}]

erlquad:area_query(0, 0, 3999, 2999, Q2),       % [#big_square{...}, #tiny_circle{...}, #tiny_circle{...}]

erlquad:area_query_deep(0, 0, 3999, 2999, Q2),  % [[], [[#big_square{...}, [[], [], ...]], [[[], ...[]]]]]

erlquad:area_query_any(IsSquare, 0, 0, 1999, 1499, Q2),       % true

erlquad:area_query_any(IsSquare, 2000, 1500, 3999, 2999, Q2), % false

erlquad:area_query_fold(CountCirclesFold, 0, 2000, 0, 3999, 2999, Q2), % 2

erlquad:area_query_fold(CountCirclesFold, 0, 2000, 0, 3999, 1499, Q2), % 1

erlquad:area_query_fold(CountCirclesFold, 0, 2000, 0, 3999, 749, Q2),  % 0

erlquad:objects_any(IsSquare, Q2), % true

erlquad:objects_fold(CountCirclesFold, 0, Q2), % 2

erlquad:objects_all(Q2), % [#big_square{...}, #tiny_circle{...}, #tiny_circle{...}]

erlquad:objects_deep_all(Q2), % [[], [[#big_square{...}, [[], [], ...]], [[[], ...[]]]]]

```

Define 'COMPILE_NATIVE_ERLQUAD' (e.g. "rebar compile -DCOMPILE_NATIVE_ERLQUAD") for HiPE compilation.

## Modules ##

erlquad