The postal code coordinates for geonames are derived from the main data base and often all postal codes of a city are mapped to the coordinates of the city centre.
We have now calculated average postal code coordinates from a data set with over 100.000 geo located hotels. (more on hotels later)
With this average coordinate per postal code we could update 3800 records in our postal code data set. The coordinates should now be pretty accurate for postal code areas with a lot of international hotels.
Here a list of the major cities with the number of postal codes affected by this update :
Code:
countrycode | placename | count
-------------+--------------+-------
DK | København K | 13
DK | København V | 18
ES | Barcelona | 38
ES | Bilbao | 12
ES | Córdoba | 11
ES | Granada | 15
ES | Madrid | 37
ES | Málaga | 15
ES | Oviedo | 12
ES | Sevilla | 17
ES | Valencia | 17
ES | Zaragoza | 12
FI | Helsinki | 12
HU | Budapest | 70
IT | Bologna | 18
IT | Firenze | 23
IT | Genova | 14
IT | Milano | 35
IT | Napoli | 20
IT | Palermo | 20
IT | Roma | 55
IT | Torino | 22
IT | Venezia | 18
IT | Verona | 16
LU | Luxembourg | 18
NO | Oslo | 29
PL | Gdańsk | 12
PL | Kraków | 77
PL | Poznań | 16
PL | Warszawa | 37
PL | Wrocław | 11
PT | Albufeira | 38
PT | Funchal | 40
PT | Lisboa | 94
PT | Porto | 31
SE | Göteborg | 15
SE | Stockholm | 25
TR | Istanbul | 31
ZA | Johannesburg | 11