[Qgis-user] Convert symbology of qgis layer into PyQGIS code to define renderer

[Manuel Campagnolo]

Olá Gustavo

How do I apply the named style afterwards in PyQGIS from the style qml 
file as the example below?

Thanks again

Manuel

<!DOCTYPE qgis PUBLIC 'http://mrcc.com/qgis.dtd' 'SYSTEM'>
<qgis simplifyLocal="1" labelsEnabled="0" simplifyMaxScale="1" 
simplifyDrawingTol="1" simplifyDrawingHints="1" simplifyAlgorithm="0" 
version="3.18.1-Zürich" readOnly="0" hasScaleBasedVisibilityFlag="0" 
minScale="100000000" maxScale="0" styleCategories="AllStyleCategories">
   <flags>
     <Identifiable>1</Identifiable>
     <Removable>1</Removable>
     <Searchable>1</Searchable>
     <Private>0</Private>
   </flags>
   <temporal durationUnit="min" enabled="0" startExpression="" 
fixedDuration="0" startField="" mode="0" durationField="" accumulate="0" 
endField="" endExpression="">
     <fixedRange>
       <start></start>
       <end></end>
     </fixedRange>
   </temporal>
   <renderer-v2 forceraster="0" attr="layer" enableorderby="0" 
symbollevels="0" type="categorizedSymbol">
     <categories>
       <category value="interior" render="true" symbol="0" label="Faixa 
interior"/>
       <category value="exterior" render="true" symbol="1" label="Faixa 
exterior"/>
     </categories>
     <symbols>
       <symbol name="0" clip_to_extent="1" force_rhr="0" alpha="0.7" 
type="fill">
         <data_defined_properties>
           <Option type="Map">
             <Option value="" name="name" type="QString"/>
             <Option name="properties"/>
             <Option value="collection" name="type" type="QString"/>
           </Option>
         </data_defined_properties>
         <layer enabled="1" locked="0" pass="0" class="SimpleFill">
           <Option type="Map">
             <Option value="3x:0,0,0,0,0,0" 
name="border_width_map_unit_scale" type="QString"/>
             <Option value="128,128,128,255" name="color" type="QString"/>
             <Option value="bevel" name="joinstyle" type="QString"/>
             <Option value="0,0" name="offset" type="QString"/>
             <Option value="3x:0,0,0,0,0,0" name="offset_map_unit_scale" 
type="QString"/>


[...]


On 11/06/2021 14:41, Jorge Gustavo Rocha wrote:
> Olá Manuel,
>
> There is no way to get the PyQGIS code from the style, as far as I know.
>
> But you can save the style (using the native QGIS format) and apply the
> named style afterwards in PyQGIS easily. Is this alternative workflow
> suitable for you?
>
> Regards,
>
> Gustavo
>
> On 11/06/21 12:56, Manuel Campagnolo wrote:
>> Hi
>>
>> Do you know of a way of using the style of a ,say, vector layer in
>> QGIS3 to create automatically the python code that would generate it,
>> namely the QgsSymbol part in the code below.
>>
>> Thanks
>>
>>
>> symbol1=QgsSymbol.defaultSymbol(ifn_ppsm.geometryType())
>> symbol2=QgsSymbol.defaultSymbol(ifn_ppsm.geometryType())
>> symbol3=QgsSymbol.defaultSymbol(ifn_ppsm.geometryType())
>> symbol4=QgsSymbol.defaultSymbol(ifn_ppsm.geometryType())
>> symbol5=QgsSymbol.defaultSymbol(ifn_ppsm.geometryType())
>>
>> symbol1.setColor(QColor('black'))
>> symbol2.setColor(QColor('gray'))
>> symbol3.setColor(QColor('dark green'))
>> symbol4.setColor(QColor('light green'))
>> symbol5.setColor(QColor('orange'))
>>
>> cat1=QgsRendererCategory('Improdutivos', symbol1, 'Improdutivos') #
>> category, symbol, label
>> cat2=QgsRendererCategory('Urbano', symbol2, 'Urbano')
>> cat3=QgsRendererCategory('Matos e Pastagens', symbol3, 'Matos e
>> Pastagens')
>> cat4=QgsRendererCategory('Floresta', symbol4, 'Floresta')
>> cat5=QgsRendererCategory('Agricultura', symbol5, 'Agricultura')
>> categories=[cat1,cat2,cat3,cat4,cat5] # list
>>
>> renderer = QgsCategorizedSymbolRenderer('usosolo', categories)
>> ifn_ppsm.setRenderer(renderer)
>>
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-- 
---------------------------------
Manuel Campagnolo
https://www.isa.ulisboa.pt/id/mlc