HowTo:  Calculate fields where some inputs are null values

【解决方案】
The calculation in each case applies the source value (in this case, the field Dbl1 or Dbl2) to the target field unless the source is null, in which case the target field is assigned the value zero.


VBScript:
1) Copy and paste the following sample into a Notepad file and save it with a .cal extension.

2) Load the .cal file into the Field Calculator to calculate the desired target field, setting the parser to VBScript. Substitute the desired field data source for field ‘Dbl1’ in the sample.


Dim X
if IsNull ([Dbl1]) then
X = 0
else
X = [Dbl1]
end if
__esri_field_calculator_splitter__
X



Python:
1) Copy and paste this sample into a Notepad file with a .cal extension.

2) Load the .cal file into the Field Calculator to calculate the desired target field, setting the parser to Python or Python_9.3. Substitute the desired field data source for field ‘Dbl2’ in the sample.


def X (param):
retVal = 0
if param is not None:
retVal = param
return retVal
__esri_field_calculator_splitter__
X (!Dbl2!)


See the following illustrations of a table before and after each field calculation. In the table, field Dbl1Calc was calculated using the sample VBScript code. Field Dbl2Calc was calculated using the sample Python code.

Before



After





Related Information

1. How to check for null values in the Field Calculator using PythonStarting at ArcGIS for Desktop 10.1, null values in an attribute table are returned as the string 'None' in the Field Calculator using Python. Knowing this, an if/elif statement can be used to find whether values are null or not. Here is an exampl...

Created: 7/18/2013 Last Modified: 9/18/2013

【原文链接】
http://support.esri.com/en/kno ... 41414