Compressing data to make grid codes
Latitudes and longitudes are bulky to transmit. They have a lot of digits and some peculiar punctuation. Over the years, some alternatives have risen that abbreviate a location using a simpler notation. The essential idea is to convert latitude and longitude numbers from their degree-minute-second numbers into a sequence of letters and digits that represent the same information.
We'll look at three compression schemes: the GeoRef system, the Maindenhead Locator, and NAC. Each of these encodings involves doing some arithmetic calculations to convert numbers from decimal (base 10) to another base. We'll also use a number of string operations to translate numbers to characters and characters to numbers.
Another interesting programming issue is that these encodings don't work directly with latitudes and longitudes. The problem with simply using latitudes and longitudes is that they're signed numbers: -90 (S) to +90 (N) and -180 (W) to +180 (E). Also, longitudes...
