[OSM-legal-talk] Some numbers on split ways

ant antofosm at gmail.com
Thu Feb 16 20:48:40 GMT 2012


Hi,

I thought some extra numbers could be interesting:

# of ways that turned from tainted to clean: 11
# of ways that turned from clean to tainted: 216

total # of detected split ways: 1856

cheers
ant

On 16.02.2012 12:40, ant wrote:
> Hi,
>
> although I'm late - I want to present some "hard numbers" on the effect
> of split ways.
> I've written a script that is based on the (imprecise) assumption that a
> way has resulted from a split if its version 1 has 2 or more nodes that
> another way from the same changeset has had before. Also such ways are
> discovered only if a way (pre-split) has lost at least 3 nodes from one
> version to another. So naturally the actual number of splits might
> differ from the number of splits the script detects.
> Then if a pre-split way is found to be the ancestor of another way, all
> versions that were created before the split are appended before the new
> way's version 1, with version numbers (-n ... 0), carrying original
> nodes and tags. On these extended history objects the licence status was
> evaluated with conventional WTFE logic.
>
> Input data was a small (city-sized) history extract, dated
> 2011-11-19.[1] Agreed users data and WTFE code were from 2012-01-16.[2]
>
>
> Total number of ways: 17273
> Number of ways created by denier
> - without split detection: 1129 (incl. 227 deleted)
> - with split detection: 1274 (incl. 234 deleted)
> Number of ways modified by denier[4]
> - without split detection: 381 (incl. 8 deleted)
> - with split detection: 441 (incl. 10 deleted)
>
>
> There's still lots of work to be done to make it read larger data chunks
> (currently the script reads and writes XML and is really, really slow)...
>
> I'll make the scripts available if anyone is interested in taking up the
> work. I'm not going to have much time for this during the next weeks.
>
> cheers
> ant
>
> [1]
> http://ftp5.gwdg.de/pub/misc/openstreetmap/osm-full-history-extracts/110919/xml/europe/germany/rheinland-pfalz/mainz.osh.bz2
>
> [2] http://planet.openstreetmap.org/users_agreed/users_agreed.txt
> http://planet.openstreetmap.org/users_agreed/anon_changesets_agreed.txt
> http://wtfe.gryph.de/report.tgz
> (no user or changeset overrides)
> [4] Ways affected only by harmless edits are not counted.



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