Steve, I thought about the template process, and this would likely work with the first pass, where MapServer does a basic or simple version of a set of settings after looking at the datasource,
Using the preconceived STAT string seems limiting as far as user interaction. If all the setting from the user or site config are already known, then that would work. I was looking at how to augment or adjust a specific ramp value within a set of them, but you have that possibility in your example as well. I'm interested for the most part in how to capture user input for the ramp classing. bobb >>> "Lime, Steve D (DNR)" <[email protected]> wrote: You’re always mixing things up aren’t you… I don’t think you need a special mode. This strikes me as just another special form of template output based on a query. Presently you can get layer level query data (e.g. number of results) and of course spatial and non-spatial attributes for each feature. What’s needed here is the mechanism to gather layer stats (and a definition of what those are) in either draw or query context and then a means of using or presenting them. Imaging in a new “stats” tag within a result set like so (within a resultset tag): [stats item=”foo” format=”$stddev,$min,$max”] You could use that to populate XML, JSON or just plain HTML output for use on the client. This tag would draw from a populated layerStatsObj which might consist of an array or hash of itemStatsObj’s… You could populate those objects on-the-fly or perhaps even from a file. Would probably need a new STATS … END block within a layer to drive this. Just thinking out loud. Steve From: Bob Basques [mailto:[email protected]] Sent: Thursday, February 04, 2010 8:19 AM To: Lime, Steve D (DNR); Stephen Woodbridge; Jan Hartmann Cc: MapServer Dev Mailing List; [email protected] Subject: RE: [mapserver-dev] RE: [mapserver-users] colorramp and datarangeon the fly? All, Just to mix it up a little, what about doing a half and half approach. MapServer could generate something simpler (the data basics from a data read on the fly, and return a simple ramping config file, which could be used to pass back as a file for the custom aspects. Just having these two options would open up some doors, MapServer returning a simple ramp structure as a file, could be used in a User interface to do more complicated theming for example. Once the basic data limits are known, the ramping divisions are much easier to decide on. Could this work as a compiled in module for those that need/want it instead of always in? or would it make more sense to build in, ?? Something similar to a mode=legend sort of thing, like mode=ramp_txt ?? bobb >>> "Lime, Steve D (DNR)" <[email protected]> wrote: At one point I toyed with the idea of supporting a .stats file for a layer and supplying a routine (command-line) that would populate it. The file would contain data like you're talking about. Doesn't help with the on-the-fly needs Bart was articulating. Steve -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Stephen Woodbridge Sent: Wednesday, February 03, 2010 10:39 AM To: Jan Hartmann Cc: Lime, Steve D (DNR); MapServer Dev Mailing List; [email protected] Subject: Re: [mapserver-dev] RE: [mapserver-users] colorramp and datarange on the fly? Right, I think there are two use cases: 1) data exploration - can be slower but needs flexibility 2) production serving - needs to be fast, and probably limits flexibility to some predefined models I think that there is also another angle to this, which is how the summary data is computed for example: 1) min/max/average/std 2) statistical analysis 3) binning into some number of classes 4) removing outli ers so the results are not skewedIf the data is in a database, then you can add all the analysis, slicing and dicing to the database and the rendering to mapserver. So, I think that it would be nice to be able to read some "metadata" about a layer and then use that for building the display using something like colorramp and datarange. We might want to look at ways that we could establish in mapserver for fetching the "metadata" about a layer. For example: 1) define the "metadata" in the METADATA object 2) define a .met file for a shapefile or tileindex that contained the "metadata" for that layer 3) define a separate SQL query that could be used to fetch the "metadata" for the layer 4) something similar for other layer providers. 5) scan the data in two passes to compute some simple "metadata" Thoughts? -Steve W Jan Hartmann wrote: > If you allow two passes, you can have all sorts of summarized values in > the template, to be used in the second pass, like Bart's actual extent > used for coloring. Doesn't look to difficult to implement to me, as long > as the two passes only get called when really necessary. I'm not sure if > performance is an issue for MapServer itself: if you really want high > performance, you should use the underlying format or database directly. > > Jan > > On 3-2-2010 17:02, Lime, Steve D (DNR) wrote: >> How big a change would depend on the implementation. The brute force >> approach where you simply loop through features once to compute ranges >> and then again to draw would be probably pretty straight forward and >> driver independent. Wouldn't be fast (but would be simple). Complexity >> would be added as you try and boost performance by: >> >> - allowing drivers to compute stats in their own way (e.g. add to >> the layer API something like msLayerGetStats(...)) >> - caching geometries from a first pass through the shapes for the >> second >> >> Steve >> >> BTW The color ramp support needs to be cleaned up first. I think we >> scared the originator of that code away when an RFC was originally put >> together. >> >> -----Original Message----- >> From: [email protected] >> [mailto:[email protected]] On Behalf Of Bart van >> den Eijnden >> Sent: Wednesday, February 03, 2010 5:12 AM >> To: [email protected] >> Subject: [mapserver-users] colorramp and datarange on the fly? >> >> Hi list, >> >> is it possible to have a colorramp in Mapserver based on the min and >> max value in the current extent? >> >> So instead of predefining the min and max in DATARANGE, have Mapserver >> use the min and max value of the dataset in the current extent? >> >> If not, would it be an easy change or a very complex one? >> >> Best regards, >> Bart_______________________________________________ >> mapserver-users mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/mapserver-users >> _______________________________________________ >> mapserver-dev mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/mapserver-dev >> > _______________________________________________ > mapserver-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/mapserver-dev _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users _______________________________________________ mapserver-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-dev
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