Great work! I really like this feature. It has been requested many
times, so it's really cool that its been done. Thanks for doing this.
We briefly discussed how this could be implemented a while back, and,
although the proposal back then may push the balance of implementation
in the direction of insanity..., I'd like to mention that proposal
again here for comparison.
One way to do this would be to automatically give each property some
special properties, such that the property itself could be queried for
its set of unique values, and the number of times each value has been
used.
This is immediately tricky, because you need to link each value with
its occurrence somehow (perhaps using sub-objects), but the advantage
is that:
1) You don't have to modify results printers, you just pass them the
results of the property query.
2) It allows you to query on the number of uses, for example, querying
for all property-values that have more than 10 uses, or all values of
City that have exactly 5 locations, etc.
3) It opens the way for having more meaningful property pages,
automatically having unique values linked to searches, which I think
is what people tend to expect.
As you mentioned previously, this could be difficult to implement, but
I prefer more general approaches than increasingly specific approaches
to getting at the data... although I suppose the most general solution
of all would be to implement aggregation queries.
Thanks again for this great work that I'll definitely use heavily. I
only mention the above as a point for discussion, and I expect you'll
take it in that light (coming from a dumb user with no implementation
experience).
Cheers,
Dan.
On 8 November 2011 14:08, Jeroen De Dauw <jeroended...@gmail.com> wrote:
> Hey all,
>
> I have implemented general support for value distributions in result formats
> in SMW. This email explains this feature and is meant to gather feedback on
> it before SMW 1.7 is released.
>
> == Goal ==
>
> Allow visualizing how many times each value in a result occurs, ie allow for
> creating value distributions.
>
> For example, this result set: foo bar baz foo bar bar ohi
> Will be turned into
> * bar (3)
> * foo (2)
> * baz (1)
> * ohi (1)
>
> This can then be displayed in chart formats, with the value as label and the
> occurrence count as value. Although the most obvious use for this are
> charts, it can really be used with any format.
>
> == Current implementation: how to use it ==
>
> Each format needs to add support for this functionality before you'll be
> able to use it to visualize value distributions. Right now only jqplotbar
> and jqplotpie make use of it. All formats that support this functionality
> accept 3 additional parameters:
>
> * distribution (on/off) - if a value distribution should be calculated and
> shown instead of the regular results.
> * distributionsort (asc/desc/none) - the sort of the values, by occurance
> count.
> * distributionlimit (positive whole number) - the max amount of values to
> visualize.
>
> This example will get the countries the matching cities are located in,
> count the occurance of each, and display this as a pie chart. Note the use
> of the mainlabel parameter. If this is not done, the cities themselves will
> also be put into the value distribution.
>
> {{#ask: [[Category:Locations]] [[Has location type::City]]
> | ?Located in
> | format=jqplotpie
> | distribution=on
> | mainlabel=-
> | limit=500
> }}
>
> This example will do the same query, but will only show the 10 countries
> with most matching cities, in descending order.
>
> {{#ask: [[Category:Locations]] [[Has location type::City]]
> | ?Located in
> | format=jqplotpie
> | distribution=on
> | distributionsort=desc
> | distributionlimit=10
> | mainlabel=-
> | limit=500
> }}
>
> You can see these examples and 2 others working on the mapping documentation
> wiki, making use of the example semantic data there:
> http://mapping.referata.com/wiki/Value_distribution_examples
>
> == Implementation details (technical) ==
>
> After looking into several options I decided to implement this as a result
> printer class deriving from SMWResultPrinter, requiring changes to each
> format that wants to support this behaviour, but making this relatively
> easy. This approach seems like a good balance between making this
> functionality available as easy as possible and staying sane.
>
> This class is called SMWDistributablePrinter and can be found here:
> http://svn.wikimedia.org/viewvc/mediawiki/trunk/extensions/SemanticMediaWiki/includes/queryprinters/SMW_QP_Distributable.php?view=markup
>
> Example jqplotpie implementation:
> http://svn.wikimedia.org/viewvc/mediawiki/trunk/extensions/SemanticResultFormats/jqPlot/SRF_jqPlotPie.php?view=markup
>
> == Request for comments ==
>
> Feedback is welcome. The main question for users is what names the
> parameters should use. Right now they all start with "distribution", but
> there might be a better (and shorter) name. From developers I'd like to know
> if you agree with this architecture.
>
> Cheers
>
> --
> Jeroen De Dauw
> http://www.bn2vs.com
> Don't panic. Don't be evil.
> --
>
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