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I try to create a interpolation with the follow script, the problem is that when the program tries to write QgsGridFileWriter, qgis crashes. The problem is that the different examples are to lower version for qgis, and this script is to qgis3, someone knows if i have to write some parameter in output.writeFile(), like boolean of other versions?

#Generation Interpolate data#
 uri="file:///Z:/DataScience/TragsaMoscaOlivo2017/Tutoriales QGIS/Capa 
 Predicciones/PREDICCION_oriental_I_S1.csvxField=LONG&yField=LAT&
 delimiter=%s"%(",")
 lyr=QgsVectorLayer(uri, 'Prediction','delimitedtext')
 values = (
 ('Low',0,0,'green'),
 ('Medium',1,1, 'yellow'),
 ('Large',2,2,'red'))
 QgsProject.instance().addMapLayer(lyr)
 # create a category for each item in values
 ranges = []
 for label,lower,upper,color in values:
   symbol = QgsSymbol.defaultSymbol(lyr.geometryType())
   symbol.setColor(QColor(color))
   rng = QgsRendererRange(lower, upper, symbol, label)
   ranges.append(rng)

# create the renderer and assign it to a layer
expression = 'pred_C' # field name
renderer = QgsGraduatedSymbolRenderer(expression, ranges)
lyr.setRenderer(renderer)
lyr.triggerRepaint()
#######################################################################
#Interpolation generation
layer_data=QgsInterpolator.LayerData()
layer_data.vectorLayer=lyr
layer_data.zCoordInterpolation=False
layer_data.interpolationAttribute=2 #Field
layer_data.mInputType=0 #points

tin_interpolator=QgsTinInterpolator([layer_data])
export_path ="Z:/DataScience/TragsaMoscaOlivo2017/Tutoriales 
QGIS/pythoninterpolation/output4656.asc"
rect = layer2.extent()
res = 10
#ncol =int((rect.xMaximum() - rect.xMinimum())/res)
#nrows = int( (rect.yMaximum() - rect.yMinimum() ) / res)

#Grid generation and write
 output = QgsGridFileWriter(tin_interpolator,export_path,rect,300,300)
 print(output)
 output.writeFile()
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I was having the same problem until I read through the qgis3 API docs more closely. I was able to get it to work by using .source instead of .vectorlayer. You can also try .sourceType instead of .mInputType. Here are the first few lines after your divider:

layer_data=QgsInterpolator.LayerData()
layer_data.source=lyr
layer_data.zCoordInterpolation=False
layer_data.interpolationAttribute=2 #Field
layer_data.sourceType=0 #points

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