Hi Peter

I'm actually using pazpar2 from Indexdata to merge my records; this
limits you in some ways (in particular it merges on-the-fly, which
blocks the use of your option 2 - the initial record on which the merger
is based is not guaranteed to be the most fully populated), but has a
lot of configuration options, which makes it quite flexible.

So, you can choose:

1. Which fields need to be identical for a record to be merged at all. I
was using author, title, edition when I first mailed the list, but have
found allowing records with different publication dates to be merged
just caused too many unpredictable problems, and have now added
publication date to the list of required fields. The test for identical
authors, dates etc is just a string comparison, so a proportion of
records which ought to be merged by these criteria never are, due to
typos, variant names, date formats, etc.

2. What to do with fields which differ between records which are being
merged. You can choose either 'unique', which appends all unique field
values (this is what I use for subject headings, so exactly repeated
subject headings are dropped, but variants are kept), and 'longest',
which picks the longest field value from all the candidates (this is
what I use for abstracts).

At the end of the process you have a merged record which has a 'head'
with the merged record itself, but which contains each of the original
records, so you could potentially do as you suggest and let users see
any of the input records if they wanted. However, by default this isn't
Marc but an internal format (a processed subset of the Marc input) so it
may not be much use to most users.

I'm finding the 'head' section is mostly quite usable but does often
have individual fields with strange or repeated values (eg values
identical apart from punctuation). So I'm doing some post-processing of
my own on this, but it's very arbitrary at the moment.

Graham

On 03/30/12 01:09, Peter Noerr wrote:
> Hi Graham,
> 
> What we do in our federated search system, and have been doing for some few years, is basically give the "designer" a choice of what options the user gets for "de-duped" records.
> 
> Firstly de-duping can be of a number of levels of sophistication, and a many of them lead to the situation you have - records which are "similar" rather than identical. On the web search side of things there are a surprising number of real duplicates (well maybe not surprising if you study more than one page of web search engine results), and on Twitter the duplicates well outnumber the original posts (many thanks 're-tweet').
> 
> Where we get duplicate records the usual options are: 1) keep the first and just drop all the rest. 2) keep the largest (assumed to have the most information) and drop the rest. These work well for WSE results where they are all almost identical (the differences often are just in the advertising attached to the pages and the results), but not for bibliographic records.
> 
> Less draconian is 3) Mark all the duplicates and keep them in the list (so you get 1, 2, 3, 4, 5, 5.1, 5.2, 5.3, 6, ...). This groups all the similar records together under the sort key of the first one, and does enable the user to easily skip them.
> 
> More user friendly is 4) Mark all duplicates and hide them in a sub-list attached to the "head" record. This gets them out of the main display, but allows the user who is interested in that "record" to expand the list and see the variants. This could be of use to you.
> 
> After that we planned to do what you are proposing and actually merge record content into a single virtual record, and worked on algorithms to do it. But nobody was interested. All our partners (who provide systems to lots of libraries, both public, academic, and special) decided that it would confuse their users more than it would help. I have my doubts, but they spoke and we put the development on ice.
> 
> I'm not sure this will help, but it has stood the test of time, and is well used in its various guises. Since no-one else seems interested in this topic, you could email me off list and we could discuss what we worked through in the way of algorithms, etc.
> 
> Peter
> 
> 
>> -----Original Message-----
>> From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of graham
>> Sent: Wednesday, March 28, 2012 8:05 AM
>> To: [log in to unmask]
>> Subject: Re: [CODE4LIB] presenting merged records?
>>
>> Hi Michael
>>
>> On 03/27/12 11:50, Michael Hopwood wrote:
>>> Hi Graham, do I know you from RHUL?
>>>
>> Yes indeed :-)
>>
>>> My thoughts on "merged records" would be:
>>>
>>> 1. don't do it - use separate IDs and just present links between related manifestations; thus
>> avoiding potential confusions.
>>
>> In my case, I can't avoid it as it's a specific requirement: I'm doing a federated search across a
>> large number of libraries, and if closely similar items aren't merged, the results become excessively
>> large and repetitive. I'm merging all the similar items, displaying a summary of the merged
>> bibliographic data, and providing links to each of the libraries with a copy.  So it's not really
>> FRBRization in the normal sense, I just thought that FRBRization would lead to similar problems, so
>> that there might be some well-known discussion of the issues around... The merger of the records does
>> have advantages, especially if some libraries have very underpopulated records (eg subject fields).
>>
>> Cheers
>> Graham
>>
>>>
>>> http://www.bic.org.uk/files/pdfs/identification-digibook.pdf
>>>
>>> possible relationships - see http://www.editeur.org/ONIX/book/codelists/current.html - lists 51
>> (manifestation)and 164 (work).
>>>
>>> 2. c.f. the way Amazon displays rough and ready categories (paperback,
>>> hardback, audiobooks, *ahem* ebooks of some sort...)
>>>
>>> On dissection and reconstitution of records - there is a lot of talk going on about RDFizing MaRC
>> records and re-using in various ways, e.g.:
>>>
>>> http://www.slideshare.net/JenniferBowen/moving-library-metadata-toward
>>> -linked-data-opportunities-provided-by-the-extensible-catalog
>>>
>>> Cheers,
>>>
>>> Michael
>>>
>>> -----Original Message-----
>>> From: Code for Libraries [mailto:[log in to unmask]] On Behalf
>>> Of graham
>>> Sent: 27 March 2012 11:06
>>> To: [log in to unmask]
>>> Subject: [CODE4LIB] presenting merged records?
>>>
>>> Hi
>>>
>>> There seems to be a general trend to presenting merged records to users, as part of the move towards
>> FRBRization. If records need merging this generally means they weren't totally identical to start with,
>> so you can end up with conflicting bibliographic data to display.
>>>
>>> Two examples I've come across with this: Summon can merge
>>> print/electronic versions of texts, so uses a new 'merged' material
>>> type of 'book/ebook' (it doesn't yet seem to have all the other
>>> possible permutations, eg book/audiobook). Pazpar2 (which I'm working
>>> with at the
>>> moment) has a merge option for publication dates which presents dates as a period eg 1997-2002.
>>>
>>> The problem is not with the underlying data (the original unmerged values can still be there in the
>> background) but how to present them to the user in an intuitive way. With the date example, presenting
>> dates in this format sometimes throws people as it looks too much like the author birth/death dates
>> you might see with a record.
>>>
>>> I guess people must generally be starting to run into this kind of display problem, so it has maybe
>> been discussed to death on ... wherever it is people talk about FRBRIzation. Any suggestions? Any
>> mailing lists, blogs etc any can recommend for me to look at?
>>>
>>> Thanks for any ideas
>>> Graham