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I have a polygon layer that has donuts and also exterior parts. Using python, I am able to get access to each part, but what I would like to know is using arcpy, once I have a part, how do I go about deleting all the vertices for that part. This is what I have enter image description here

and this is what I would like to end up with enter image description here

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  • If you can safely assume the first multi-part ring is the largest, then you could rewrite the shape with the first ring. Unfortunately, that's one of those ass-u-me assumptions that tend to backfire. Anyway you do it, you'll be using a cursor to either update the current shape or (preferably) inserting a new row into a disimproved feature class with the trucated geometry.
    – Vince
    Commented Jan 6, 2016 at 22:43
  • You should have a look at this q&a.
    – Hornbydd
    Commented Jan 7, 2016 at 0:34
  • Even though it's not really an arcpy solution, the Eliminate Polygon Part tool does exactly what you want. It requires an Advanced license.
    – GISGe
    Commented Jan 7, 2016 at 7:38

2 Answers 2

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You can delete entire geometry parts without having to delete each vertex. Refer to this page on python access to shapes and interior rings from ArcGIS Help There is also a GP tool that will remove the doughnut holes. It is on GitHub

As far as deleting parts of a multi-part feature, you will need a strategy for identifying the part you want to delete. Size (absolute or relative) or # of vertices are options, as is a spatial relationship to other features (intersect with FC to see if it overlaps anything). Provide more detail in the question and perhaps some ideas will pop up...

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# UNION WITH NO GAPS FILL TO FILL THE RINGS  
union_polygons = os.path.join("in_memory", "union_polygons")
arcpy.Union_analysis(polygon_feature, union_polygons, gaps="NO_GAPS")

# DISSOLVE SINGLE PART  
dissolve_polygons = os.path.join("in_memory", "dissolve_polygons")
arcpy.Dissolve_management(union_polygons, dissolve_polygons, multi_part="SINGLE_PART")

# JOIN FIELDS TO SINGLE PART FEATURE WITH NO RINGS
spatial_join_polygons = os.path.join("in_memory", "spatial_join_polygons")
arcpy.SpatialJoin_analysis(
    dissolve_polygons, polygon_feature, spatial_join_polygons, join_type="KEEP_COMMON"
  )
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