Setting a string Output parameter from the python script tool in ArcGIS

Question

import sys, arcpy 
arcpy.env.workspace = "C:\Scratch" 
Environment_Index = arcpy.GetParameterAsText(0) 
Measure = arcpy.GetParameterAsText(1) 
if Environment_Index == "Percentage of Environmental Hazard": 
 if Measure == "0-25%": 
 Expression = '"per_Envi_H" >0 AND "per_Envi_H" <25' 
 elif Measure == "25-50%": 
 Expression = '"per_Envi_H" >25 AND "per_Envi_H" <50' 
 elif Measure == "50-75%": 
 Expression = '"per_Envi_H" >50 AND "per_Envi_H" <75' 
 elif Measure == "75-100%": 
 Expression = '"per_Envi_H" >75 AND "per_Envi_H" <100' 
 else: 
 Expression = "0" 
 print Expression 
 arcpy.SetParameter(2, Expression) 
elif Environment_Index == "Percentage of Flooded Area": 
 if Measure == "0-25%": 
 Expression = '"Per_Flood" > 0 AND "Per_Flood" <25' 
 elif Measure == "25-50%": 
 Expression = '"Per_Flood" > 25 AND "Per_Flood" <50' 
 elif Measure == "50-75%": 
 Expression = '"Per_Flood" > 50 AND "Per_Flood" <75' 
 elif Measure == "75-100%": 
 Expression = '"Per_Flood" > 75 AND "Per_Flood" <100' 
 else: 
 Expression = "0" 
 print Expression 
 arcpy.SetParameter(2, Expression) 
else: 
 if Measure == "0-50kgs/yr": 
 Expression = '"pest_kg" >0 AND "pest_kg" <50' 
 elif Measure == "50-100kgs/yr": 
 Expression = '"pest_kg" >50 AND "pest_kg" <100' 
 elif Measure == "100-250kgs/yr": 
 Expression = '"pest_kg" >100 AND "pest_kg" <250' 
 elif Measure == "250-500kgs/yr": 
 Expression = '"pest_kg" >250 AND "pest_kg" <500' 
 else: 
 Expression = "0" 
 print Expression 
 arcpy.SetParameter(2, Expression)

I am trying to get a string as an output parameter from the script tool and use the string as the expression for the select by attribute tool.

My user wanted to have a range of values to be selected from a field, I thought it was an easy process by writing a python code.

I tried using the set parameter for the output parameter. I don't understand where the problem is. This is my script tool in the model builder enter image description here

• Marcelo Villa: Could you paste the code and format it with the {} button instead of attaching a picture? It makes it easier to review and test the code.
• Geeta Nakkina: My Expression in the model builder is empty and selecting all the values
• Kadir Şahbaz: What is the type of output that you specified in Parameters tab on Script Properties dialog? String?
• Geeta Nakkina: I specified it as a string

Answer 1

I guess double-quotes are making trouble. When you use Query Builder, you see that the field names are added without double quotes.

enter image description here

Use your code like that:

import arcpy, sys
arcpy.env.workspace = "C:/Scratch"
environment_index = arcpy.GetParameterAsText(0)
measure= arcpy.GetParameterAsText(1)
if environment_index == "Percentage of Environmental Hazard":
 if measure== "0-25%": 
 expression = 'per_Envi_H > 0 AND per_Envi_H < 25' 
 elif measure== "25-50%": 
 expression = 'per_Envi_H > 25 AND per_Envi_H < 50' 
 elif measure== "50-75%": 
 expression = 'per_Envi_H > 50 AND per_Envi_H < 75' 
 elif measure == "75-100%": 
 expression = 'per_Envi_H > 75 AND per_Envi_H < 100' 
 else: 
 expression = "0" 
elif environment_index == "Percentage of Flooded Area": 
 if measure == "0-25%": 
 expression = 'Per_Flood > 0 AND Per_Flood < 25' 
 elif measure == "25-50%": 
 expression = 'Per_Flood > 25 AND Per_Flood < 50' 
 elif measure == "50-75%": 
 expression = 'Per_Flood > 50 AND Per_Flood < 75' 
 elif measure == "75-100%": 
 expression = 'Per_Flood > 75 AND Per_Flood < 100' 
 else: 
 expression = "0" 
else: 
 if measure == "0-50kgs/yr": 
 expression = 'pest_kg > 0 AND pest_kg < 50' 
 elif measure == "50-100kgs/yr": 
 expression = 'pest_kg > 50 AND pest_kg < 100' 
 elif measure == "100-250kgs/yr": 
 expression = 'pest_kg > 100 AND pest_kg < 250' 
 elif measure == "250-500kgs/yr": 
 expression = 'pest_kg > 250 AND pest_kg < 500' 
 else: 
 expression = "0" 
arcpy.SetParameter(2, expression)

if statement doesn't define a scope in Python. So, you don't have to use arcpy.SetParameter() in every if branch.