As explained earlier, there are different levels in my ZIPScribble Maps:
- Level 1 ZIPScribble Map: Only the first digit of the postcode is compared. Thus, a discontinuity is detected, for example, between postal codes 8679 and 9000, but no discontinuity is detected between 8399 and 8400.
- Level 2 ZIPScribble Map: The first two digits are compared. Thus, a discontinuity is detected between postal codes 8679 and 9000 as well as between 8399 and 8400.
- The Level 3 ZIPScribble Map works analogously.
What I find interesting, comparing the ZIPScribble Maps of Italy to those of Switzerland, is that in the Italian maps the difference between levels 2 and 3 is not very big. In Switzerland level 3 is much more fragmented than level 2. In Italy, level 3 seems to distinguish big cities from their surroundings.
Consider, for example, Genova on the coast of the Mediterranean sea in the top-left/north-west corner of the ZIPScribble Map. At level 3, Genova (coloured bright green) stands separate from the surrounding towns (purple/fuchsia). Similarly, the cities of Milano, Parma, Modena, Bologna, Florence, Perugia, Rome, Napoly and Palermo stand out at level 3.
Finally, in celebration of the recent political events in Italy I had fun producing these maps (exact colours courtesy Wikimedia):