ArcMap 10.4 Field Calculator Manhole Invert Lelels

Question

Hi all,

This one should be an easy.

I have a table from Collector with recorded manhole Invert depths.

When I perform simple subtraction [LID_LEVEL] - [INV1_DEPTH] I get Invert Levels replicating Lid Levels if Invert Depth is zero. I want to return zero value in those cases.

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DanPatterson_Retired · Answer

If it is simple like a two case condition check for the field calculator, I like the direct solution. With a code block you can make a mistake with the expression or the code block. like f(!LID_LEVEL! - !INV1_DEPTH!) should be f(!LID_LEVEL!, !INV1_DEPTH!)

curtvprice · Answer

Oh I get it. You are casting boolean expressions to integer in the context of a slice index, where True and False will cast to 1 and 0. >>> int(True) 1 >>> int(False) 0 >>> a - b >= 0 False >>> int(a - b >= 0) 0‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ I guess I'd rather create the code block. Readability counts. Calculate FIeld Expression f(!LID_LEVEL! - !INV1_DEPTH!) ‍ Calculate Field Code block ("pre-logic script code") def f(lev, dep): if lev > dep: val = lev - dep else: val = 0 return val‍‍‍‍‍‍

DanPatterson_Retired · Answer

You can still use the field calculator if you just have one condition to test. I have substituted your field names with 'a' and 'b' in the example, then wrapped it up with them I am sure you can follow along. The condition is on the right, the False, True slice is on the left ... [do this if False, do this if True][condition to check] .... is the syntax a = 10 b = 11 [a - b, 0][a - b <=0.0] 0 # returns zero # try a positive a = 10 b = 9 [a - b, 0][a-b <=0.0] 1 # returns the difference # now it looks horrible with your field names, but so what # NOTE use the Python parser... field names enclosed in !'s # [!LID_LEVEL! - !INV1_DEPTH!, 0][!LID_LEVEL! - !INV1_DEPTH! <=0.0] ‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍