[Talk-GB] Postcode finder based on OSM data

[Matt Williams]

On 17 March 2011 12:09, Craig Loftus <craigloftus+osm at googlemail.com> wrote:
> Nice work Matt, I look forward to an alternative to RM's postcode finder.
>
>> - Largely based on the Karlsruhe Schema (including the associatedStreet relation for grouping houses together)
>
> A question with regard to your handling of associatedStreet; how do
> you tag for and 'parse' multi-segment streets?
>
> I've been using addr:street but the idea of the associatedStreet
> relation does appeal to me. However having just experimented with it,
> its not clear to me what the current 'popular' practice is for
> associating houses with multi-segment streets? The 'spec' for
> associatedStreet directs processors to consider type=street relations
> to be equivalent, but differs (cf. [1] & [2]) in only allowing one
> instance of the street role. One might naturally create a separate
> street relation that defines the street and then add that as a child
> of associatedStreet, but this seems to be precluded by the 2 relations
> being considered equivalent.
>
> A practical approach would seem to be for an implementation to accept
> multiple instances of the street role, as either ways or relations.
> Where a child-relation of role=street is treated as a collection of
> segments.

In my mapping and in the Postcode Finder I've been simply adding
multiple all the relevant street ways as role=street such as at
http://www.openstreetmap.org/browse/relation/555028. The 'street' and
'associatedStreet' relations are technically different and I've only
been looking for associatedStreets but perhaps that will change. I
would prefer if people would settle on just one of the two relations
and in my mind associatedStreet seems simpler (with the addition of
multiple role=street members) and so that is what I've been using in
my mapping and parsing.

I had considered grouping all the street segments together into a
sub-relation and then adding that relation as the role=street in the
associatedStreet but that didn't really seem to add any useful
information to the database and seems over-engineered.

-- 
Matt Williams
http://milliams.com