[mapserver-users] Clustering based on a classified column

[Stephan Holl]

Hello Tamas,

thanks for you reply.

Tamas Szekeres <szekerest at gmail.com>, [20111019 - 19:04:22]

> I'm not sure exactly what you would like to achieve. 

Sorry, let my show an example to make it clear:
I have a classified layer based on the following CLASSES

CLASS
  NAME "bar"
  EXPRESSION ('[typ]'='bar')
  STYLE
    SYMBOL "bar"
   END
END

CLASS
  NAME "foo"
  EXPRESSION ('[typ]'='foo')
  STYLE
    SYMBOL "foo"
   END
END

... more CLASSes

As you see, they are classified by the values of the column [typ].

What I want to achieve is adding a label (with the
Cluster:FeatureCount as text) if the different classes have more
identical attributes within the MAXDISTANCE.

What I currently do is adding another CLASS:
LABELITEM "Cluster:FeatureCount"
CLASS
  NAME "Clustered foo"
  EXPRESSION ("[Cluster:FeatureCount]" > "1" && '[typ]'='foo')
  STYLE
    SYMBOL "foo"
   END
  STYLE
    SIZE 20
    OFFSET 15 15
    SYMBOL "circle"
    COLOR 255 0 0
  END
  LABEL
    FONT freesans
    TYPE TRUETYPE
    SIZE 10
    COLOR 255 255 255
    OFFSET 15 15
    ALIGN CENTER
    PRIORITY 10
    BUFFER 1
    PARTIALS TRUE
    POSITION cc
  END
END

CLASS
  NAME "foo"
  EXPRESSION ('[typ]'='foo')
  STYLE
    SYMBOL "foo"
   END
END

... more CLASSes

The problem of the above is, that I have to include the SYMBOL 'foo'
also in the clustered CLASS, because the normal SYMBOL does not show up
(because it is not there since it is clustered now...).

But: I have to do that for all classes I have currently (about 25).

My thinking was about a dynamic classification and clustering based on
the attributes of a specific column ([typ]), but I cannot make it work.

Does this make more sense to you now?

> The GROUP setting
> specifies which features may belong to the same cluster. This setting
> can be an expression (including the feature attributes) which
> evaluates to a string value. Features with different group string
> value are not used within the same cluster.
> 
> The FILTER setting can also be an expression (including the feature
> attributes or the aggregated attributes) which evaluates to a boolean
> value. This boolean determines whether the particular shapes should
> be filtered out or not in the clustering process.

Thanks for your clarification, this is helpful for my understanding.
 
> You can continue to use the CLASSITEM setting or class EXPRESSION
> (including the aggregated attributes, like Cluster:FeatureCount in
> the expressions) to control which class is used to display a
> particular clustered shape.
> 
> What do you mean by validation in the GROUP or FILTER expressions?

Does my above example more sense to you?

Best

	Stephan

> 
> 2011/10/19 Stephan Holl <stephan.holl at intevation.de>
> 
> > Dear mapservers,
> >
> > I am playing arround with the CLUSTER-directive and I am going fine.
> >
> > Though there are some questions left I cannot answer by myself and
> > the documentation.
> >
> > Is it possible to cluster a POINT layer based on a specific
> > attribute columns? THis column is the  basis of the classification
> > of the layer.
> >
> > What I want to achive is adding a label to each CLASS if the
> > Cluster:FeatureCount is > 1.
> >
> > The docs do not make it clear for me if CLUSTER:GROUP or
> > CLUSTER:FILTER is the correct stuff. Neither of them work during
> > tests.
> >
> > Could someone tell me if this could be done with the CLUSTERing?
> >
> > And the bonus-question: if this is possible, are validation-pattern
> > taken into account within GROUP or FILTER?
> >
> > Looking forward to your suggestions.
> >
> > TIA
> >
> > Best regards
> >
> >        Stephan
> >
> > --
> > Stephan Holl <stephan.holl at intevation.de> | Tel.: +49 (0)541-33 508
> > 3663 Intevation GmbH, Neuer Graben 17, 49074 OS  |  AG Osnabrück -
> > HR B 18998 Geschäftsführer:  Frank Koormann, Bernhard Reiter, Dr.
> > Jan-Oliver Wagner
> >
> > _______________________________________________
> > mapserver-users mailing list
> > mapserver-users at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/mapserver-users
> >
> >



-- 
Stephan Holl <stephan.holl at intevation.de> | Tel.: +49 (0)541-33 508 3663
Intevation GmbH, Neuer Graben 17, 49074 OS  |  AG Osnabrück - HR B 18998
Geschäftsführer:  Frank Koormann, Bernhard Reiter, Dr. Jan-Oliver Wagner
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