Field calculation using Python Parser

Question

I have a table as like below:

I want to generate python script to calculate the value Low, Medium and High into a single layer.

I tried using this script:

Parser:
Python

Expression:
Reclass( Flood_Severity )

Code Block:
def Reclass ( Flood_Severity ):
    if ( FAT = 1 and FV = 1 and FD < 3):
        return "Low"
    elif ( FAT = 1 and FV = 1 and FD >= 3):
        return "Medium"
    elif ( FAT = 1 and FV = 2 and FD = 1):
        return "Low"
    elif ( FAT = 1 and FV = 2 and FD > 1 and FD < 4):
        return "Medium"
    elif ( FAT = 1 and FV = 2 and FD=4):
        return "High"

But it failed. May I know how to fix the script?

Answer 1

You are going to get errors for using = as a comparison operator , it should be two ==.

See: Python Operators

And you need to include all the fields you use in the function, when declaring and calling it:

def Reclass ( FAT, FV, FD ):
   ...

And when you call it:

Reclass( !FAT!, !FV!, !FD! )