Python for Secret Agents

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 ...