[OSM-talk] Semi-automated edits - postal code database

[Jochen Topf]

Hi!

On Wed, Oct 03, 2012 at 11:10:05AM +0000, Svavar Kjarrval wrote:
> I'm trying to find a good method to maintain data from outside sources.
> The data in question is the Icelandic postal code database (which they
> say we may use freely). My searches on the OSM wiki have been fruitless
> so far.
> 
> The idea is to maintain the data in associatedStreet relations. Each
> relation has a tag called 'götuskrá:id' which value is a direct
> reference to the row ID in the files we retrieve from the postal
> company's website. The file formats available are CVS and XML 1.0. The
> script would presumably go ever each associatedStreet relation and make
> any changes (if appropriate) when a götuskrá:id tag is found. The output
> could be an OSM change file loaded into an editor like JOSM to be
> uploaded manually. Maybe an automated process later when we're confident
> that everything is done correctly, and of course after submitting the
> script(s) for review by the local community.

It is not a good idea to add some random ID of your favourite database to
OSM, because nobody except you can understand this ID and do useful things
with it. It just confuses mappers and make it more difficult to edit the
data. For every change somebody does to the data they have to know what this
tag means so that they can properly do their edit. And if they don't, people
will just mess up your data and you will not be able to use this ID for
syncing the data anyways.

And in this case I don't even see why you need it. You have street names and
postal codes in both OSM and the Icelandic postal code database. If something
changes you can find out which combinations changed and apply those changes
to OSM easily just based on the postal code and street name. There is no
need for those IDs.

And, btw, you should not use the associatedStreet relation. It solves the same
problem as the addr:street tags on nodes and buildings but in a much more
complicated way. The overwhelming majority of all addresses are tagged with
addr:street (there are nearly 15 million addr:street tags vs. only 18.000
associatedStreet relations).

Jochen
-- 
Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/  +49-721-388298