Hi Alec,
For "Early 3rd Century BC" I would have probably said "300BC - 275BC"
with going all the way to 250 BC being the "First Half" or something
similar. But I don't know if there really is a "correct" answer.
Joe
On 06/11/13 14:35, Alec Turner wrote:
> This is a subject close to my own heart as I wrote and maintain the
> date translation software used within MuseumIndex+, etc. You're right
> about variation in the meaning of circa, not just across different
> systems, but when applied to different date spans (e.g. in
> MuseumIndex+ it's default meaning, which can also be tweaked per
> customer, can be different when applied to months, years, decades and
> centuries). Ultimately we've always allowed access to the generated
> "earliest" and "latest" date values so these can be adjusted manually
> if the builtin rules get it wrong. I'd be curious to know what people
> would ideally like their systems to do.
>
> Finally, I couldn't resist testing out your "Early 3rd Century BC"
> example - MuseumIndex+ interprets this as "299 BC - 250 BC". Are we in
> the right ballpark? (because I'd be happy to try and improve on this
> if people think we're not).
>
> ... Alec Turner
>
> On 04/11/2013 14:03, Joseph Padfield wrote:
>> Hi,
>>
>> I had a little look at this a few years ago while experimenting with the
>> conversion of free text dates to semantic searchable dates. I was
>> working with the questions: Given the language used within the TMS
>> DisplayDate field; which paintings/artists do we want someone to find
>> when they run a date based search for a particular year or even a range
>> of years?
>>
>> I ended up using a lot of regular expressions in Perl to create an
>> internally consistent display text field and then used a set of simple
>> rules to indicate what date range the display date referred to. As I
>> said it was a few years ago for an in-house R&D project, but if it is
>> useful you can see some of the details at:
>> http://research.ng-london.org.uk/wiki/index.php/National_Gallery_Display_Date_Descriptors
>>
>>
>>
>> These ranges where just an example and the actual date range used could
>> be different for different systems, ideally though you just need to add
>> the description of your logic into the "help" information.
>>
>> Joe
>>
>> PS the one I always like was what years are meant by: "Early 3rd Century
>> BC" :-)
>>
>> On 04/11/13 11:54, David Croft wrote:
>>> I've been working on this problem on an off for a while now, but from
>>> the other side as it were. Trying to extract the dates that the record
>>> author meant from what they actually wrote.
>>> There are a LOT of different date formats out there and I've yet to
>>> see a really good solution.
>>> I'm coming at this problem from a software angle, trying to decode
>>> dates automatically, so my desires for date formats may be different
>>> to yours.
>>> But I really, really, really wish that date information was stated
>>> explicitly and consistently.
>>>
>>> Plenty of collections use modifiers like 'circa', 'early' or 'first
>>> half', but then don't use these consistently.
>>> In one record 'late 20th century' means 1950 to 2000, in another place
>>> it will mean 1975 to 2000.
>>> These sort of date modifiers never seem to get explicitly defined for
>>> the collection which means that what one collection means by 'circa'
>>> is different to what another collection means.
>>> The modifiers also mean different things to different dates, 'circa
>>> 1950' may mean 1945 to 1955 but is `circa 1950s' 1950 to 1959 or 1945
>>> to 1965?
>>> There are lots of records with dates like '80s' where you just have to
>>> assume the century information or '1940-50s' where you assume it means
>>> 1940 to 1959.
>>>
>>> So for me, the best way is just to provide the upper and lower bounds
>>> for date period in full, i.e. not `circa 1955' but instead `1950/1/1
>>> to 1959/12/31`.
>>> Or if that's not possible, define exactly what you mean by 'circa',
>>> 'late', 'early' etc and make that information available where anyone
>>> looking at your records can see it.
>>> For example, are you going to use the word 'circa'? or just put a 'c'
>>> on the front of the date i.e. 'c1950'?
>>> If there are two dates in a field does the circa apply to just the
>>> first one or both? i.e. is 'circa 1950 to 1960' the same as 'circa
>>> 1950 to circa 1960'?
>>> If you are saying 'circa 19th century' do you mean up to 25 years
>>> either side? 50 years? 75?
>>> Software can decode any format you use as long as we know what the
>>> rules are.
>>>
>>> P.S
>>> There are some truly interesting date fields out there and I've been
>>> keeping a list as part of my really tricky testing data.
>>> Some of my favourites are '25 feb ?', 'circa pre world war two',
>>> 'early or late 19th or 20 century' and 'c18-1 to c--01?'
>>>
>>> David
>>>
>>> ****************************************************************
>>> website: http://museumscomputergroup.org.uk/
>>> Twitter: http://www.twitter.com/ukmcg
>>> Facebook: http://www.facebook.com/museumscomputergroup
>>> [un]subscribe: http://museumscomputergroup.org.uk/email-list/
>>> ****************************************************************
>>> .
>>>
>>
>
> .
>
--
*Joseph Padfield*
Conservation Scientist
Scientific Department
The National Gallery
Trafalgar Square
London WC2N 5DN
44 (0)20 7747 2553
http://research.ng-london.org.uk
http://www.twitter.com/JoePadfield
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