ArcGIS – find duplicate field-values in table

A short Python-Code in field-calculator will do the job – the result is in a new field with 0/1-values indicating if there is a duplicate for a given attribute.


Step 1: Add a field e.g. “Duplicate” (type short integer)

Step 2: Open field-calculator for this field and use the following Python-Code (enable Python and show code-block like shown in the screenshot):

uniqueList = []
def isDuplicate(inValue): 
  if inValue in uniqueList: 
    return 1 
    return 0

In the bottom-field (Duplicate =) enter


FIELDNAME is the field in which you want to find the duplicates.


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