Now that's just gorgeous.
On Wed, Dec 4, 2013 at 7:13 PM, Nyall Dawson <nyall.daw...@gmail.com> wrote: > I haven't had a chance to properly plan this out, but something which > has been playing in the back of my mind is the idea of "table > legends". Take a look at the legend in this map: > http://www.cartogrammar.com/images/vba/cervical_cancer.jpg > I'm thinking the user could specify the variable which is changed > along each axis, along with the min/max value for that axis and number > of rows/columns for the table. Then the classes would be generated > automatically (maybe equal ranges? equal count? user specified?) and > the symbol automatically generated for each cell in the table. > > The size and spacing of each cell could be user controlled, so that > this type of legend would also work for symbol layers. > > As I said, I haven't really sat down to work out exactly how this > would work yet... it's just a rough idea which I've been toying with! > > Nyall > > > On 4 December 2013 22:34, Denis Rouzaud <denis.rouz...@gmail.com> wrote: > > Hi régis, > > > > Martin Dobias will make a proposal soon for a legend refactoring. > > You should see with him how to let those things happen in the future in > the > > new legend. > > > > Cheers, > > > > Denis > > > > > > > > On 04. 12. 13 12:08, Régis Haubourg wrote: > >> > >> Hi All, > >> we have a long lasting problem with proportionnal legends in QGIS. It > gets > >> more problematic with V2, as those maps are so beautiful and popular. > >> > >> I'm starting some brainstorming to clarify fonctionnal specifications > what > >> we actually want to have legends in layers registry and composer > working. > >> > >> Here are some exemples of what I would love to see in legends: > >> - [0] proportionnal circles or square with 1 to 5 classes > >> - [1] proportionnal symbols AND colors > >> > >> Now that we have expressions everywhere, we probably will have to handle > >> legends differently than in other GIS, where legend is generated once, > >> when > >> user tune symbology. Let me explain: > >> > >> - user can now define expressions for size, color, rotation, border > >> width... > >> for any sub-marker (1 to n) of a symbol. > >> - Moreover, we can use conditionnal expressions, and scale dependent > >> conditions ($scale variable). > >> - QGIS is also a server, we need to be able to generate legends working > on > >> really displayed datas. > >> > >> Conclusion, It now is impossible to correctly pre-generate the legend by > >> analysing symbology properties. > >> > >> Does this sound possible to developpers to explore some other way? We > >> could > >> read real dataset to collect informations to build a legend, and > >> eventually > >> do some statistical classification to get discrete classes from > continuous > >> data? > >> > >> We could do that on live or on-demand update maybe. > >> > >> My idea was to collect rendered object in current canvas and current > >> scale. > >> BUT.. we can face discrete data - some kind of SELECT DISTINCT can do > the > >> trick - , OR continuous data - we need then to do some statistical > >> classification to reduce the legend to 1 - 10 classes to get it > readable. > >> We also need some intelligence in those statistical classifications: > >> - round values to keep it readable > >> - display separate classes only if size or color distance is long > enough > >> so > >> that human eye sees some difference on screen. ie: do not display for > >> classes if symbol size varies from 0.5 to 0.7... > >> - add some options in GUI to choose number of classes, type of legend > >> rendering.. > >> - keep the classification process fast (subset of data with random > >> sampling?) > >> - test all use cases, I'm mostly thinking of points symbols, but lines > >> and > >> polygons must not be forgotten. > >> > >> I'm sure plenty of scientists have already been theorizing all this. Any > >> opinions? Could this be an idea for GSoC or other kind of training > course? > >> > >> I'll be pleased to get feedback from the community. > >> > >> Cheers > >> Régis > >> > >> [0] http://kelsocartography.com/blog/?p=2224 > >> [1] http://www.geoclip.fr/img/bicol.jpg > >> > >> > >> > >> > >> > >> -- > >> View this message in context: > >> > http://osgeo-org.1560.x6.nabble.com/Legend-for-proportionnal-symbols-and-expression-based-symbols-tp5092635.html > >> Sent from the Quantum GIS - Developer mailing list archive at > Nabble.com. > >> _______________________________________________ > >> Qgis-developer mailing list > >> Qgis-developer@lists.osgeo.org > >> http://lists.osgeo.org/mailman/listinfo/qgis-developer > > > > > > _______________________________________________ > > Qgis-developer mailing list > > Qgis-developer@lists.osgeo.org > > http://lists.osgeo.org/mailman/listinfo/qgis-developer > _______________________________________________ > Qgis-developer mailing list > Qgis-developer@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/qgis-developer >
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