Thanks, both James and Markus!

Yes, James, dating someone or something to 15th century makes sense. But in
my discipline, photo history, it kind of drives me batty when I see a
museum or library say a photographer was active 19th century- suggesting
they may have been making photos 20 years before the invention of
photography! But I can certainly understand its usefulness elsewhere. So
thanks for alerting me to P2031 & P2032. This is all still very new to me.

d

On Mon, Nov 23, 2015 at 1:22 PM, James Heald <[email protected]> wrote:

> Your best bet for "plain-language" dates is almost certainly
> post-processing with a script language of your choice.
>
> It *can* be done in SPARQL, but it's not pretty and may not be
> sufficiently efficient.  See:
>
>    http://tinyurl.com/qx8rmv7
>
> achieved by adding the following in the SELECT line:
>
>     (CONCAT(str(day(?dob)),' ',?month_label,' ',str(year(?dob))) AS
> ?dmy_dob)
>
>
> and the following in the main WHERE block, to look up the label for the
> n'th Gregorian month:
>
>   ?month p:P279 ?stmt .
>   ?stmt  v:P279 wd:Q18602249 .
>   ?stmt  q:P1545 ?month_no .
>   FILTER (xsd:integer(?month_no) = month(?dob)) .
>   ?month rdfs:label ?month_label filter (lang(?month_label) = "en").
>
>
> ----
>
> Turning to the other parts of your post: the best way to distinguish
> day-accurate for year-accurate (or century-accurate) dates is to get use
> more detailed "node" form of the date property, and then look at the
> corresponding value of wikibase:timePrecision
>
> So the following snippet selects for day-specific dates of death, but only
> year-specific dates of birth:
>
>        ?item p:P569/psv:P569 ?birth_date_node .
>        ?birth_date_node wikibase:timePrecision "9"^^xsd:integer .
>        ?item p:P570/psv:P570 ?death_date_node .
>        ?death_date_node wikibase:timePrecision "11"^^xsd:integer .
>
> ----
>
> I am sure we do have a number of people born "15th century"; and certainly
> buildings or artworks with such a date that is only century-specific.
>
> "Active" dates can be specified using
>
> P2031  work period start
> P2032  work period end
>
> or, for spot dates
>
> P1317  floruit
>
> these dates can be year-specific, or decade-specific, or century-specific,
> in the usual way.
>
>
> "circa" can be specified by adding to the date the qualifier
>
> P1480  sourcing circumstances
>
> with the value Q5727902 "circa"
>
> Some other potential values are given at
>    https://www.wikidata.org/wiki/Property_talk:P1480
>
> This query gives counts for the values currently in use.
>    http://tinyurl.com/ou4jlup
>
>
> All of these should ideally be watched out for when retrieving data.
>
>
> Hope this helps!
>
> All best,
>
>    James.
>
>
>
>
>
>
>
>
> On 23/11/2015 16:55, David Lowe wrote:
>
>> I'm working at the moment finding places of birth for photographers who
>> have birthdates but lack locations (my query is below). Ultimately I'll be
>> comparing WD's photographer info to my own database of photographer
>> biographies. This leads me to a few questions regarding dates:
>>
>> How can I query out the date data in plain language (20 July 1982 vs.
>> 1982-07-20T00:00:00Z)?
>>
>> I need this so I can distinguish between someone actually born January 1,
>> 1900 and someone whose birth date is given as simply 1900, or someone with
>> a date given simply as 19th century.
>>
>> How do folks feel about giving lifedates as centuries (born: 19th
>> century)?
>> I personally would not do it. In my own database, if lifedates are not
>> known we give "active" dates. For example I would have
>> Alexander Möhlen (German, active 1900s-1910s)
>> <https://www.wikidata.org/wiki/Q2642705>.
>>
>> Is there a concept such as "Period of Activity" that could be used, or
>> would others find this desirable?
>>
>> Is there a way to record uncertainty in dates (circa or ca.)?
>>
>> Many thanks in advance,
>> David
>>
>>
>> PREFIX wd: <http://www.wikidata.org/entity/>
>> PREFIX wdt: <http://www.wikidata.org/prop/direct/>
>> PREFIX wikibase: <http://wikiba.se/ontology#>
>> PREFIX p: <http://www.wikidata.org/prop/>
>> PREFIX v: <http://www.wikidata.org/prop/statement/>
>> PREFIX q: <http://www.wikidata.org/prop/qualifier/>
>> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
>>
>> SELECT ?photographer ?photographerLabel ?photographerDescription ?dob
>> WHERE
>> {
>>     ?photographer wdt:P106 wd:Q33231 .
>>     ?photographer wdt:P569 ?dob .
>>    FILTER NOT EXISTS { ?photographer wdt:P19 ?pob .}
>>
>>
>>    SERVICE wikibase:label {
>>       bd:serviceParam wikibase:language "en" .
>>   }
>> } Order by ?photographerLabel
>>
>>
>>
>> _______________________________________________
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>> [email protected]
>> https://lists.wikimedia.org/mailman/listinfo/wikidata
>>
>>
>
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