[Qgis-user] R: using field calculator to do a spatial update for a table usingdata from an overlapping geometry.

[enricofer]

Thank you,
I realized that I was in the right way when i seen new expression functions introduced by new 2.6 version. There will be a new getfeature that has the same goal of the one called dbvalue implemented by the plugin. 
A Great improve will come also from the  memory field new feature that allows to calculate in the fly new fields without having to modify table structure. And here a set of function to reference to other layers would be very useful.
As I want to extend the reference functions  set I would be interested in suggestion and testing feedback.

Regards

Enrico ferreguti


----- Messaggio originale -----
Da: "Järnefelt Jouko [via OSGeo.org]" <ml-node+s1560n5169947h26 at n6.nabble.com>
Inviato: ‎28/‎10/‎2014 15:03
A: "enricofer" <enricofer at gmail.com>
Oggetto: Re: using field calculator to do a spatial update for a table usingdata from an overlapping geometry.

Hi, 

Enrico: Nice work I have to say! I think this kind of functionality should be part of the QGIS core. Or atleast I'm missing a way to do "join attributes by location" kind of task in processing toolbox as well as in geographical modeler. 

Cheers, 
Jouko 

-----Alkuperäinen viesti----- 
Lähettäjä: [hidden email] [mailto:[hidden email]] Puolesta Damien Stephens 
Lähetetty: 24. lokakuuta 2014 8:50 
Vastaanottaja: enricofer; [hidden email] 
Aihe: Re: [Qgis-user] using field calculator to do a spatial update for a table using data from an overlapping geometry. 

Enrico you have made my day  ! - much appreciated. 
I will have a look at it and get back to you on how I progress. 
Thanks Again 
Damien 

-----Original Message----- 
From: [hidden email] [mailto:[hidden email]] On Behalf Of enricofer 
Sent: Thursday, 23 October 2014 6:14 PM 
To: [hidden email] 
Subject: Re: [Qgis-user] using field calculator to do a spatial update for a table using data from an overlapping geometry. 

You are lucky. 
I was developing a plugin with reference functions that fits to solve similar problems. 
I see your question and I implemented a dbwithin function You can get a development version from github: 
https://github.com/enricofer/refFunctions/archive/master.zip

put the inside directory refFunctions-master in your plugin directory (typical .qgis/python/plugins in your user profile directory if you work in 
windows) 
then restart qgis 

If everything ok you will find under field calculator dialog a new group of experimental  functions called 'reference' with a function dbwithin: 

<http://osgeo-org.1560.x6.nabble.com/file/n5169107/reffunc.png> 

Syntax 
dbwithin(targetLayer,targetField) 

Arguments: 
targetLayer; the name of a currently loaded layer, for example 'myLayer'. 
targetField; a field in target layer we want as result when source feature is within target feature, for example 'myField'. If targetField is equal to '$geometry' The WKT geometry of targetFeature willbe retrieved 
        
Number of feature tested is limited to 100000 to avoid time wasting loops 
        
Example: 
dbwithin('targetLayer','TargetField') 
dbwithin('targetLayer','$geometry') 

Let me know if that resolvs 

PS: Qgis guys are releasing 2.6 version that contains some new expression funtions very very interesting for you...... 

Bye. 

Enrico 





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