Converting latitude and longitude to decimal values

Joe Colson picture Joe Colson · Jul 16, 2009 · Viewed 63.2k times · Source

I have GPS information presented in the form:

36°57'9" N 110°4'21" W

I can use the javascript functions of Chris Veness to convert degrees, minutes and seconds to numeric degrees, but first need to parse the GPS info into the individual latitude and longitude strings (with NSEW suffixes). I have read related posts on stackoverflow, but am not a regex expert (nor a programmer) and need some help with the parsing function. What's the best way to parse this string into latitude and longitude for use in the conversion function?

The result of all this will be a Web link that one can click on to see a Google map representation of location.

Answer

Gavin Miller picture Gavin Miller · Jul 16, 2009

To parse your input use the following.

function ParseDMS(input) {
    var parts = input.split(/[^\d\w]+/);
    var lat = ConvertDMSToDD(parts[0], parts[1], parts[2], parts[3]);
    var lng = ConvertDMSToDD(parts[4], parts[5], parts[6], parts[7]);
}

The following will convert your DMS to DD

function ConvertDMSToDD(degrees, minutes, seconds, direction) {
    var dd = degrees + minutes/60 + seconds/(60*60);

    if (direction == "S" || direction == "W") {
        dd = dd * -1;
    } // Don't do anything for N or E
    return dd;
}

So your input would produce the following:

36°57'9" N  = 36.9525000
110°4'21" W = -110.0725000

Decimal coordinates can be fed into google maps to get points via GLatLng(lat, lng) (Google Maps API)