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I have a whole lot of polygon shape files, many of which have got duplicate nodes. This makes processing difficult as almost all tools (erase, union, calculate area) do not work.

I found that by removing duplicate nodes from the 'offending' polygons the shape files become usable. However there are well over a hundred shape files and going through all of these is a nightmare.

Is it possible to automate the process using ArcPy or VB? If it is possible, how can it be done? If not, are there any free libraries in .NET (C# or VB.NET) or Python that can be used to perform this task?

Thank you.

I tried the python shape file library ( but I found that when it is done removing the duplicate nodes, ArcMap is still unable to handle the shape files, giving the same errors as before.

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Have you tried repair geometry? It's documented to remove dup vertices in shapefiles.… – T. Wayne Whitley Nov 17 '12 at 14:06
@T.WayneWhitley: I tried that tool and it works very well. Thank you. Can you write your comment as an answer so I accept it? Thanks. – Alex Essilfie Nov 18 '12 at 18:29
up vote 4 down vote accepted

Repair Geometry is documented to remove duplicate vertices in shapefiles, see:

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