[Thuban-list] sized point data

Moritz Lennert mlennert at club.worldonline.be
Wed Oct 20 09:44:44 CEST 2004

On Wed, October 20, 2004 7:48, Jan-Oliver Wagner said:
> On Wed, Oct 20, 2004 at 12:12:53AM +0200, Moritz Lennert wrote:
>> I just did a fresh cvs checkout and tried it and it looks promising.
>> Obviously, the inclusion of point size in the classification would make
>> life even more beautiful...
> hm, actually it is considered by the classification.

Either I didn't see how, or I was not clear enough. What I meant was that
presently it seems that I have to set the size by hand. I can't just tell
thuban that I want each point to be displayed automatically in a size that
is proportional to a given column value (this could be a special case of
"unique values" but where the classification does not result in a color
ramp, but in a "size ramp"). The former is ok if I have a few sites or
only few different sizes, but if I have several hundred "sites" then the
latter becomes necessary.

For the implementation of the proportionate size it would also be
necessary to be able to determine a scale factor, i.e. a constant by which
to multiply the size of all sites in order to adapt the sizes to the map.

>> And to push you all further to new heights: how about a combination of
>> point size and point color representing two separate classifications
>> (ex:
>> point size=current population size of a city and point color=population
>> growth rate between 1990 and now). Would this be very complicated ?
> I will move my mind about this feature.
> I added this to the Roadmap feature proposals anyway since it is
> definitly interesting.

Actually if the "automatic" size is implemented seperately from the
classifier, and the classifier remembers the sizes, then it would be
possible to reclassify the different point (colors) according to any given
column. At present, using the iceland_sample_size session, when I
reclassify the cultural landmarks, they all go back to the same size and I
have to reset the size manually. If the classifier could remember the
sizes (given either manually or through some automatic proportionate
mechanism, then the combination of sizes and colors should be no problem.

>> But before I give the impression of ingratitude, I would like to thank
>> you
>> all  (and especially Jan) for this great new feature !
> Hope it helps you for the case you describe some months ago.

It does. We are getting closer to having something that I might be able to
sell to my colleagues.

Many thanks again (including to the Deutsche Bahn ;-)) !


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