If else if in ArcMap Field Calculator (Python)

Help! I think I am missing something that must be so obvious but I cannot figure out what I am doing wrong. Here's some background:

I have one short integer field (MajAspNum) that has values 1-10. I have another text field (Direction) that needs to be filled. I am trying to use the Field Calculator to calculate it but am not succeeding in any way. I should know what I'm doing but I just can't seem to make it work.

Pre-logic Script Code:


def des(num):
if num = 1:
    return "Flat"
elif num = 2:
    return "North"
elif num = 3:
    return "Northeast"
elif num = 4:
    return "East"

elif num = 5:
    return "Southeast"
elif num = 6:
    return "South"
elif num = 7:
    return "Southwest"
elif num = 8:
    return "West"
elif num = 9:
    return "Northwest"

elif num = 10:
    return "North"
else:
    return "N/A"




Direction = 
des (!MajAspNum!)

It gives me a GeoProcessing error of invalid syntax on line 2. I have tried just selecting by attributes in the attributes table and then using field calculator more simply on just those but that gives me a very weird error that literally makes no sense. I'm hoping my error is a really obvious fix to someone out there!

Answer

A switch statement is ideal for what you want to do. Since Python doesn't support switch statements, you can use dictionary mapping to accomplish the same thing.

def des(num):
    the_dict = {1: 'Flat',
                2: 'North',
                3: 'Northeast',
                4: 'East',
                5: 'Southeast',

                6: 'South',
                7: 'Southwest',
                8: 'West',
                9: 'Northwest',
                10: 'North'
    }
    return the_dict.get(num, 'N/A')