Qarj / geohexa

Latitude and Longitude combined into one number

geohexa 0.1.0

Latitude and Longitude combined into one small string

Try it here: https://qarj.github.io/geohexa/

Principles

• Compress co-ordinate size by using alphabet as well as digits
• Case insensitive
• No decimal point to worry about, or negative signs
• No need to worry about which is the latitude and which is the longitude
• More digits = more precision
• A geohexa with similar (higher significant digit) numbers are near each other

Why

• Separate Latitude and Longitude has multiple representations making it particularly confusing
• Easy to say and type into a mobile device - don't have to worry about case or changing keyboard modes for special characters
• No need for separate Lat and Lon headings / fields

How

• Uses 0-9 plus a-z giving 36 possible numbers in a single digit - a hexatrigesimal
• First digit is a longitude - compressing all possible longitudes into 36 digits
• second digit is a latitude
• Now the you have compressed the world into a 36 x 36 grid, your location is the midpoint of the 'rectangle'
• For more precision, keep adding digits (lon lat lon lat lon ...)
• can end of a odd number of digits

That's it!

Example geohexas

Geohexa	Lat , Lon	Notes
null	0 , 0	Null geohexa
0	0 , -175	Single character geohexa
00	-87.5 , -175	Two character geohexa
zz	87.5 , 175
hsxatoom	51.483892, -0.604316	Windsor Castle
hszaotyy	51.504468, -0.085198	The Shard, London
hszaounu	51.507898, -0.087555	London Bridge
hszaqu88	51.505540, -0.075338	Tower Bridge
pqe5cdjz	40.748403, 73.985661	Empire State Building

Example implementations

The Android app, Pointy Arrow, implements the java version of geohexa. See it here:

https://play.google.com/store/apps/details?id=qarj.pointyarrow

Python 3

Example - lat lon to geohexa

geohexa --lat 51.481874 --lon -0.112564

Produces output:

geohexa is hszaLoe3t
Converted back to lat, lon: 51.48185656721534, -0.11256441948635994

By default, the accuracy is at least within 3 meters.

Example - geohexa to lat lon

geohexa --hexa aqL5k4f8my

Produces output:

Lat: 40.71083658407638 Lon: -74.00899669924554

Example - accurate to at least 0.1 of a meter

geohexa --lat -46.896522 --lon 168.130336 --acc 0.1

Produces output:

geohexa is y8tm9cofw68
Converted back to lat, lon: -46.8965212881992, 168.1303359584042

Further notes

--verbose flag produces a lot of info on how the geohexa is calculated

--null flag outputs the lat lon of a null geohexa

--help flag outputs help

test_geohexa.py runs the unit tests

Java

First compile the Java:

javac -d . Geohexa.java
javac -d . Run.java

Example - lat lon to geohexa

java geohexa.Run 51.481874 -0.112564

Produces output:

geohexa is hszaLoe3t
Converted back to lat, lon: 51.48185656721534, -0.11256441948635994

By default, the accuracy is at least within 3 meters.

Example - geohexa to lat lon

java geohexa.Run aqL5k4f8my

Produces output:

Lat: 40.71083658407638 Lon: -74.00899669924554

Example - accurate to at least 0.1 of a meter

java geohexa.Run -46.896522 168.130336 0.1

Produces output:

geohexa is y8tm9cofw68
Converted back to lat, lon: -46.8965212881992, 168.1303359584042

Further notes

To run the unit tests, ensure the JUnit environment is set up correctly. Refer to https://www.tutorialspoint.com/junit/junit_environment_setup.htm for full details.

Then run testJava.bat on Windows machines to compile and execute the tests.

JavaScript

After cloning the repo, double click on geohexa.html.

Or just head over to: https://qarj.github.io/geohexa/

Further notes

To run the unit tests, first do one time setup:

• Install nodejs: https://nodejs.org/en/
• Install karma npm install -g karma
• Install qunit-qunit npm install -g karma-qunit
• Install qunit npm install -g qunitjs

Then run the tests as follows:

• start karma start (on Windows)
• karma run

You can create your own JavaScript unit test config by changing directory to your project, then:

• karma init

Which will create karma.conf.js (after you answer questions about your desired setup).

In an organisation with SSL interception, you may need to:

• npm config set strict-ssl false
• npm cache verify

PHP

Check the README.md in the php directory.