How to identify feature vertices that are part of a donut hole in ArcGIS 10?

MartinScheiber

Hello everybody,

I´m exporting the coordinates of polygon vertices to a CSV-File using the "Feature Vertices to Points" and then the "Export feature attributes to ASCII"-tools.

Some of these polygons have holes (donuts). Can I do the analysis in a way, that in the resulting CSV-File it´s possible to identify if a point has been part of the outer boder or the inner border (donut) of the polygon?

Thanks, Martin

MarcinGasior

You can try this Python script which reads vertices coordinates, recognises inner ring and writes '1' for inner ring coordinates:

def main():     try:         import arcpy, sys, traceback         polygon = r"C:\tmp\Test.gdb\PolygonWithInnerRings"         txtFile = open(r"C:\tmp\PolygonToTXT.txt","w")         headerLine = (", ").join(["VertObjID", "X", "Y", "InRing"])         txtFile.write(headerLine + "\n")          rows = arcpy.SearchCursor(polygon)         for row in rows:             feature = row.SHAPE #get the geometry into variable             featureID = row.OBJECTID #adjust this if not in geodatabase              partNum = 0             #feature can have multiple parts - first goes iteration through parts             for featurePart in feature:                 part = feature.getPart(partNum) #the output is Array of points                  isInnerRing = "0"                 linesLst = []                  #iterate through points                  for pnt in part:                     if pnt:                         vertexLine = (", ").join([str(featureID), str(pnt.X), str(pnt.Y), isInnerRing])                         linesLst.append(vertexLine)                     else:                         isInnerRing = "1"                         linesLst.append("InRing")                                          #remove duplicated point and write to file                 linesLst.pop(linesLst.index("InRing")-1)                 for line in linesLst:                     if line != "InRing":                         txtFile.write(line + "\n")                  partNum += 1          del rows, row         txtFile.close()      except:         print arcpy.GetMessages()         # Get the traceback object         tb = sys.exc_info()[2]         tbinfo = traceback.format_tb(tb)[0]          # Concatenate information together concerning the error into a         #   message string         pymsg = tbinfo + "\n" + str(sys.exc_type)+ ": " + str(sys.exc_value)          # Return python error messages for use with a script tool         arcpy.AddError(pymsg)          # Print Python error messages for use in Python/PythonWin         print pymsg  if __name__ == '__main__':     main()