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I want to run the calculation based on what the user chooses from the drop-down menu. For Example, if the user chooses the second option, then the calculation will be using the second formula. I can run my code but the calculation only uses the first formula. How to make use the other formula?

self.addParameter(QgsProcessingParameterEnum(
        self.RAD_PERCENTAGE,"Age",
        options = ['More than 10 years','5 to 9 years','Below than 5 years']
    ))

for options in self.RAD_PERCENTAGE:
        
        if 'options == 0':
            field = processing.run("qgis:fieldcalculator", 
                {'INPUT':parameters[self.INPUT_VECTOR],
                'FIELD_NAME':'NewRadius',
                'FIELD_TYPE':0,
                'FIELD_LENGTH':10,
                'FIELD_PRECISION':4,
                'NEW_FIELD':True,
                'FORMULA':'Radius-(Radius * 20/100)',
                'OUTPUT': 'memory:'
                },context=context, feedback=feedback, is_child_algorithm=True)
            newradius = field['OUTPUT']
        
        elif 'options == 1':
            field = processing.run("qgis:fieldcalculator", 
                {'INPUT':parameters[self.INPUT_VECTOR],
                'FIELD_NAME':'NewRadius',
                'FIELD_TYPE':0,
                'FIELD_LENGTH':10,
                'FIELD_PRECISION':4,
                'NEW_FIELD':True,
                'FORMULA':'Radius-(Radius * 10/100)',
                'OUTPUT': 'memory:'
                },context=context, feedback=feedback, is_child_algorithm=True)
            newradius = field['OUTPUT']
        
        else:
            field = processing.run("qgis:fieldcalculator", 
                {'INPUT':parameters[self.INPUT_VECTOR],
                 'FIELD_NAME':'NewRadius',
                 'FIELD_TYPE':0,
                 'FIELD_LENGTH':10,
                 'FIELD_PRECISION':4,
                 'NEW_FIELD':True,
                 'FORMULA':'Radius-(Radius * 0/100)',
                 'OUTPUT': 'memory:'
                },context=context, feedback=feedback, is_child_algorithm=True)
            newradius = field['OUTPUT']
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  • 2
    Remove the quotes: options == 1. Also there is no need to iterate over self.RAD_PERCENTAGE.
    – MrXsquared
    Sep 14, 2022 at 8:02

1 Answer 1

5
...
def processAlgorithm(self, parameters, context, feedback):
    option = self.parameterAsEnum(parameters, self.RAD_PERCENTAGE, context)
    if option == 0: # More than 10 years
        ...
    elif option == 1: # 5 to 9 years
        ...
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  • 1
    To elaborate on that: if-statements in python check whether a condition is true. Strings in quotes always evaluate to true. You don't want to evaluate a string, you want to evaluate the result of the comparison of option to 0 or 1. Thats why you don't need quotes.
    – til_b
    Sep 14, 2022 at 8:23

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