I received some asset management data, and the state of it led me to write this script to determine if there were any values duplicated in the GIS ID field. There’s a number of ways that one can do this, but I do like to know as many methods as possible before settling on the optimised one.
In Line 18, the attribute value is stored as a key in the dictionary, along with the number of occurrences of that value. In Line 21, only the keys for which there is more than one occurrence is displayed. I wrote it as a function so that I could generate a report for all the layers in the map document.
Writing this report out to a table may be more useful, especially if there are lots of duplicates, but then one may as well run Summary Statistics.