[Qgis-user] QGIS variables calculated from other variables

[Nikolai Bezdna]

Sorry, but I meant setting qgis variables, not calculation of attribute field values.

I can use field values for data-driven style properties where possible and recalculate them when needed, but I don’t want to overload db with styling properties for each feature. Also I have some scale dependent rule-based styling, so I would like to have an option to set variable (i.e. @road_width_z1) for just one scale and calculate others (@road_width_z2…) from it on the fly. Like having an expression instead of a constant value.
   
Or do you mean writing a custom function with function editor GUI and then running it every time my project loads?

> On 13 Jan 2016, at 19:54, Nuno de Santos Loureiro <nlourei at ualg.pt> wrote:
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> Easy: Field calculator...
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> Citando Nikolai Bezdna <mofoyoda at gmail.com>:
> 
>> Is it possible to set qgis variable calculated from another one?
>> Like this: @road_width2 = @road_width1 * 1.5
>> So I can style in a CartoCSS manner - set only the basic variables and calculate lots of others on the fly.
>> That’ll greatly help with some complicated styles.
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> Nuno
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> Nuno de Santos Loureiro (PhD)
> Faculdade de Ciências e Tecnologia - DCTMA - Ed. 8
> Universidade do Algarve
> Campus de Gambelas
> 8005-139 FARO   (Portugal)
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