Awesome

GeohashNif

Drop in replacement fot the Elixir native Geohash encode/decode library implemented as a NIF

Installation

The package can be installed by adding geohash_nif to your list of dependencies in mix.exs:

def deps do
  [{:geohash_nif, "~> 1.0"}]
end

Basic Usage

iex(1)> Geohash.encode(42.6, -5.6, 5)
"ezs42"

iex(1)> Geohash.decode("ezs42")
{42.605, -5.603}

iex(1)> Geohash.neighbors("ezs42")
%{
  "e" => "ezs43",
  "n" => "ezs48",
  "ne" => "ezs49",
  "nw" => "ezefx",
  "s" => "ezs40",
  "se" => "ezs41",
  "sw" => "ezefp",
  "w" => "ezefr"
}

iex(1)> Geohash.adjacent("ezs42","n")
"ezs48"

iex(1)> Geohash.bounds("u4pruydqqv")
%{
  max_lat: 57.649115324020386,
  max_lon: 10.407443046569824,
  min_lat: 57.649109959602356,
  min_lon: 10.407432317733765
}

Full documentation can be found at https://hexdocs.pm/geohash_nif.

Differences to Geohash

For compatibility reasons Geohash.neighbors/2 returns a map with string as keys, but passing the option keys: :atoms a different implementation is called which returns a map with atom as keys.

The atoms implementation is ~30% faster and uses ~40% less memory.

Benchmarks

Included witht the library there is a complete suite of benchmarks available as the bench mix task.

Usage:

$ mix help bench

Bench Geohash NIF against Gehohash native Elixir implementation

## Usage

mix bench <bench_name> [<bench_name> ...]

If <bench_name> is omitted or one of them is `all` runs all the benchmarks.

<bench_name> can be a single value or a list of values separated by spaces.
Invalid values are simply ignored.

Valid <bench_name> values are

  • encode
  • decode
  • bounds
  • adjacent
  • neighbors
  • decode_to_bits

## Examples

  • $ mix bench - runs all the benchmarks
  • $ mix bench all - runs all the benchmarks
  • $ mix bench encode - runs the encode benchmark
  • $ mix bench encode decode - runs the encode and decode benchmarks
  • $ mix bench xxx all yyy - runs all benchmarks

Detailed benchmarks (including memory measurements): benchmarks.txt

License

GohashNif is released under the Apache License 2.0 - see the LICENSE file.

The code for the C geohash library is released under the MIT license - see the LICENSE.geohash