Thanks, Andrew, for the clarification. This makes perfect sense.
I don't see a problem with one bridge having two IDs in some external database. We already have this for other ID-like properties for other reasons. What is important though is that it still is a single bridge, and should therefore be one item.
Your clarification is reassuring since it suggests that the problem is not overly common after all. Maybe one can just merge these cases manually. Once the (multiple) ids are found in the merged items, avoiding future duplicates will be done as usual (which is still difficult with the Scottish Heritage ids since we have many legit Wikidata items that have the same id -- but this at least is an independent problem).
Regards,
Markus
On 03.06.2015 13:48, Andrew Gray wrote:
This particular case is something of a known problem - we've encountered it with some of the other heritage-building identifier lists as well.
Bridges often span a river which is the border for two jurisdictions (in this case, council areas). Each local area counts it as a historic building, and because the national lists are aggregated from local lists, it gets two entries in the main list, one as Fife and one as Edinburgh. A similar case in Wales is the Menai Suspension Bridge, which is 4049 from the Gwynedd register and 18572 from the Anglesey one (Wikidata, at Q581526, only lists one identifer).
The lack of deduplication is probably intentional rather than a bug, and both entries are "correct". Perhaps one way to handle this for Wikidata would be to, hmm, say something like "if the item is some kind of a bridge, then allow two IDs" in the constraints?
I can't immediately think of any bridges which cross national borders *and* are a heritage building in both countries, but we'd see the same thing there, with it having identifiers from both sides.
Andrew.
On 2 June 2015 at 12:12, Markus Krötzsch markus@semantic-mediawiki.org wrote:
Another interesting type of Scottish historic orphans are those that are duplicates of items that do have site links. Even very prominent ones are duplicated, such as
https://www.wikidata.org/wiki/Q17569486 (dup) https://www.wikidata.org/wiki/Q933000 (real item)
Interestingly, they use different Scotland IDs, and it does indeed seem that Historic Scotland also contains duplicates:
http://data.historic-scotland.gov.uk/pls/htmldb/f?p=2200:15:0::::BUILDING,HL... http://data.historic-scotland.gov.uk/pls/htmldb/f?p=2200:15:0::::BUILDING,HL...
Overall, this seems to be an example of an ID that really should not be considered "identity providing" since there seems to be an many-to-many relationship between Wikidata and Historic Scottland. Orphans should receive additional ids from a better source if at all possible. With the great number of seemingly legit non-functional uses of the Scotland IDs, they cannot be used in practice to detect duplicates.
Regards,
Markus
On 02.06.2015 13:01, Markus Krötzsch wrote:
On 02.06.2015 11:30, Magnus Manske wrote:
Update 2: For example, https://www.wikidata.org/wiki/Q17847522 and https://www.wikidata.org/wiki/Q17847537 have the same Scotland ID, but refer to different entities (church and churchyard, respectively). They were as two entities in the original dataset, sharing the same ID.
Yes, I noticed such cases too. From the information Wikidata, it is not clear to me why this is sometimes done and sometimes not done.
For example, these adjacent houses have the same Scotland ID but different items that each have their own coordinates (where did the coordinates come from?):
https://www.wikidata.org/wiki/Q17576211 https://www.wikidata.org/wiki/Q17576182 https://www.wikidata.org/wiki/Q17576185
In many other cases, adjacent houses with the same ID are combined into one item:
https://www.wikidata.org/wiki/Q17806587
(note, however, that the house addresses given in the ID and in the item label do not match, though they overlap on most of the houses.)
Finally, there are also cases where there are different IDs and we have several items, but they have the same labels that merge the contents of the two IDs:
https://www.wikidata.org/wiki/Q17810121 https://www.wikidata.org/wiki/Q17810137
It seems that the data was not taken from the Historic Sites database but from some different source that has its own coordinate data and a different (but seemingly arbitrary) approach to grouping sites. However, the coordinated give Historic Scotland as their reference -- I wonder if Historic Scotland might be changing frequently or exist in several versions.
Regards,
Markus
On Tue, Jun 2, 2015 at 10:26 AM Magnus Manske <magnusmanske@googlemail.com mailto:magnusmanske@googlemail.com> wrote:
Update: There appear to be quite a few items with duplicate Scotland IDs (not all of them may be erroneous!): http://wdq.wmflabs.org/stats?action=doublestring&prop=709 On Tue, Jun 2, 2015 at 10:23 AM Magnus Manske <magnusmanske@googlemail.com <mailto:magnusmanske@googlemail.com>> wrote: I created (some/most of) these items as part of the Wiki Loves Monuments UK 2014 drive, to run the campaign from Wikidata rather than from a bespoke database. This allows the community (TM) to maintain the data, rather than one poor sod (e.g., myself) having to frantically update all of it every year ;-) "Consumer" tool is here: https://tools.wmflabs.org/wlmuk/index_wd.html These are based on "official" data from National Heritage, provided to me via Wikimedia UK. Grade A (or Grade I/II* in England) structures should be noteworthy by default. It appears (as per your examples) that some of these were created as duplicates/with wrong IDs. As I said, this is based on "official" data, so it's the best I could do at the time. With mass creation, there are bound to be a few strays. If you can find some large-scale, systemic issue I'll try to fix it, but the one-offs will always fall back to manual fixing. At least, with Wikidata, we can fix them together. On Tue, Jun 2, 2015 at 10:01 AM Daniel Kinzler <daniel.kinzler@wikimedia.de <mailto:daniel.kinzler@wikimedia.de>> wrote: Am 01.06.2015 um 22:26 schrieb Markus Krötzsch: > Finally, the technical question is: Why is this even possible? I thought that, > in each language, label+description are a key (globally unique), yet here we > have many pairs of items with exactly the same label and description. Or is the > problem that no description was entered and so the system does not apply the > key? The uniqueness constraint does indeed not apply if there is no description. -- Daniel Kinzler Senior Software Developer Wikimedia Deutschland Gesellschaft zur Förderung Freien Wissens e.V. _______________________________________________ Wikidata mailing list Wikidata@lists.wikimedia.org <mailto:Wikidata@lists.wikimedia.org> https://lists.wikimedia.org/mailman/listinfo/wikidata
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