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Python None, Null, and Zero

Question asked by ntlegg on Dec 30, 2013
Latest reply on Jan 1, 2014 by Wayne_Whitley
Hi There,

I'm performing some calculations in a table where I want to filter out Null values, but keep values of zero. I am trying to use the Python Filter function, but am having some issues. When I specify that values of "None" be filtered, zero values are also filtered. I would like to only filter Null values. This is confusing me because any literature I read says that the Python None value is equal to Null.

Here's a simple form of my Python script (Pre-logic Script) in field calculator:

def trial(f1,f2):
   list = [f1,f2]
   l1 = len(filter(None,list))
   return l1

The code above runs fine, but returns undesired lengths when f1 or f2 are zero.

Can anyone tell me what I am doing wrong, or another simple way of filtering out Null values and not zero values? Thanks for your insight!

Happy New Year!