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https://github.com/stephenlb/geohash-chat-by-proximity

Geo Hashing Chat by Proximity to connect two or more users to a group chat.
https://github.com/stephenlb/geohash-chat-by-proximity

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Geo Hashing Chat by Proximity to connect two or more users to a group chat.

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README 

        
# Geohashing Chat by Proximity UPDATED



> 💡 [NEW PubNub GitHub repository for New Geo Chat](https://github.com/PubNubDevelopers/Geohashing-Chat-by-Proximity)



Use the above link to find the latest Geo Powered Chat.

Below is the older version.



# Geohashing Chat by Proximity



### Try it now: [Geohash Chat by Proximity][1]



To connect groups of two or more people by location, you will take lat/long values and reduce the resolution of accuracy, and by doing this you can expand the coverage of proximity.  You can use multiple resolutions at once or a fixed resolution.  



> Get Source Code: [GitHub Repository for Geo Chat by Proximity][2]



![Geohashing Chat Conversations based on Proximity Zoom Level][3]



## Basics of Geo Hashing



Next we'll cover some source code snippet for geo hashing lat/long coords. It is fairly simple to increase the radius of lat/long position by reducing the accuracy of the float values.  Using this you can expand the circle and collect a Lat/Long.



    // -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

    // Geo Hash

    // -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

    function geohash( coord, resolution ) {

        var rez = Math.pow( 10, resolution || 0 );

        return Math.floor(coord * rez) / rez;

    }



![Acquire Lat Long Chat Proximity Location][4]



## Geo Hashing Resolution "Zoom"



"Zoom" levels, basically several different cartesian grids with larger and smaller granularity.  Once a Geofencing event fires, you will publish to a set of channels corresponding with each zoom level.  Zoom levels are important as that is how we actually construct the link between Geofencing and PubNub.  Zoom level is the resolution/de-resolution of the Cartesian coordinates Lat/Long (think X,Y coord).  By reducing the resolution of the lat/long coord we can construct a channel name that hits 1 box of the grid.  Less resolution means larger the boxes and is required to determine a PubNub Channel that is associated.



    // Create Proximity Channel

    channel = geohash( pos.latitude, 0 ) + '' + geohash( pos.longitude, 0 );



This will create a very wide circle and generate a channel name used to connect.  Next connect to PubNub with this channel name.



    // Connect to Proximity Channel

    pubnub.subscribe({

         channel : channel,

         message : receive,

         connect : ready,

        presence : presence

    });



![Acquired Latitude Longitude Chat Proximity Group][5]



## Multiplexing 9 Boxes



You will calculate the surrounding squares to extend the taper and radius in a way that provides more accuracy. This will remove the "fencing" effect.



## Geo Hashing with PubNub Conclusion



That's it! You simply reduce the resolution of a geo coordinate and use that as a channel name on PubNub.  Also check out the browser's `navigator.geolocation.getCurrentPosition(...)` method to acquire lat/long in a chrome/firefox/ie/opera/mobile/safari browser.



> Also checkout the [PubNub Connected Car Solution Kit][7]



![Geohashing Chat Conversations based on Proximity Nearby][6]



  [1]: http://stephenlb.github.io/geohash-chat-by-proximity/

  [2]: https://github.com/stephenlb/geohash-chat-by-proximity

  [3]: http://i.stack.imgur.com/tV9S7.jpg

  [4]: http://i.stack.imgur.com/LUAvv.png

  [5]: http://i.stack.imgur.com/GQD3n.png

  [6]: http://i.stack.imgur.com/u0uE0.png

  [7]: http://www.pubnub.com/developers/connected-car/