Kim Ollivier a couple of years ago gave example Python code to create a polygon with a hole in it. This involved a null point between the outer and inner rings of data.
The help does not go into detail on this; though there is a deprecated script tool Create Features From Text File, from the Samples Toolbox, which supports creation of donut holes (Inner Rings).Since this script is such a good short and detailed example for writing geometry, and tricky to locate in the install folder, I just went ahead and pasted it here, so people can find it in the forums when search for how to write polygons with donut holes or other geometry.
'''----------------------------------------------------------------------------------
Tool Name: CreateFeaturesFromTextFile
Source Name: CreateFeaturesFromTextFile.py
Version: ArcGIS 9.1
Author: Environmental Systems Research Institute Inc.
Required Argumuments: An Input Text File containing feature coordinates
An Input Character designating the decimal separator used in the text file.
An output feature class
Optional Arguments: A spatial reference can be specified. This will be the
spatial reference of the output fc.
Description: Reads a text file with feature coordinates and creates a feature class
from the coordinates.
----------------------------------------------------------------------------------'''
import string, os, sys, locale, arcgisscripting
gp = arcgisscripting.create()
gp.overwriteoutput = 1
msgErrorTooFewParams = "Not enough parameters provided."
msgUnknownDataType = " is not a valid datatype. Datatype must be point, multipoint, polyline or polygon."
msgErrorCreatingPoint = "Error creating point %s on feature %s"
# sets all the point properties
def createPoint(point, geometry):
try:
point.id = geometry[0]
point.x = geometry[1]
point.y = geometry[2]
# When empty values are written out from pyWriteGeomToTextFile, they come as 1.#QNAN
# Additionally, the user need not supply these values, so if they aren't in the list don't add them
if len(geometry) > 3:
if geometry[3].lower().find("nan") == -1: point.z = geometry[3]
if len(geometry) > 4:
if geometry[4].lower().find("nan") == -1: point.m = geometry[4]
return point
except:
raise Exception, msgErrorCreatingPoint
try:
# get the provided parameters
inputTxtFile = open(gp.getparameterastext(0))
fileSepChar = gp.getparameterastext(1)
outputFC = gp.getparameterastext(2)
# spatial reference is optional
outputSR = gp.getparameterastext(3)
# make sure the text type specified in the text file is valid.
inDataType = inputTxtFile.readline().strip().lower()
dataTypes = ["point", "multipoint", "polyline", "polygon"]
if inDataType.lower() not in dataTypes:
msgUnknownDataType = "%s%s" % (inDataType, msgUnknownDataType)
raise Exception, msgUnknownDataType
# create the new featureclass
gp.toolbox = "management"
gp.CreateFeatureclass(os.path.split(outputFC)[0], os.path.split(outputFC)[1], inDataType, "#", "ENABLED", "ENABLED", outputSR)
# create a new field to assure the id of each feature is preserved.
idfield = "File_ID"
gp.addfield(outputFC, idfield, "LONG")
# get some information about the new featureclass for later use.
outDesc = gp.describe(outputFC)
shapefield = outDesc.ShapeFieldName
# create the cursor and objects necessary for the geometry creation
rows = gp.insertcursor(outputFC)
pnt = gp.createobject("point")
pntarray = gp.createobject("Array")
partarray = gp.createobject("Array")
locale.setlocale(locale.LC_ALL, '')
sepchar = locale.localeconv()['decimal_point']
# loop through the text file.
featid = 0
lineno = 1
for line in inputTxtFile.readlines():
lineno += 1
# create an array from each line in the input text file
values = line.replace("\n", "").replace("\r", "").replace(fileSepChar, sepchar).split(" ")
# for a point feature class simply populate a point object and insert it.
if inDataType == "point" and values[0].lower() != "end":
row = rows.newrow()
pnt = createPoint(pnt, values)
row.SetValue(shapefield, pnt)
row.SetValue(idfield, int(values[0]))
rows.insertrow(row)
# for a multipoint the text file is organized a bit differently. Groups of points must be inserted at the same time.
elif inDataType == "multipoint":
if len(values) > 2:
pnt = createPoint(pnt, values)
pntarray.add(pnt)
elif (len(values) == 2 and lineno != 2) or values[0].lower() == "end":
row = rows.newrow()
row.SetValue(shapefield, pntarray)
# store the feature id just in case there is an error. helps track down the offending line in the input text file.
if values[0].lower() != "end":
row.SetValue(idfield, featid)
featid = int(values[0])
else:
row.SetValue(idfield, featid)
rows.insertrow(row)
pntarray.removeall()
elif (len(values) == 2 and lineno == 2):
featid = int(values[0])
# for polygons and lines. polygons have a bit of logic for interior rings (donuts).
# lines use the same logic as polygons (except for the interior rings)
elif inDataType == "polygon" or inDataType == "polyline":
#takes care of
#adds the point array to the part array and then part array to the feature
if (len(values) == 2 and float(values[1]) == 0 and lineno != 2) or values[0].lower() == "end":
partarray.add(pntarray)
row = rows.newrow()
row.SetValue(shapefield, partarray)
# store the feature id just in case there is an error. helps track down the offending line in the input text file.
if values[0].lower() != "end":
row.SetValue(idfield, featid)
featid = int(values[0])
else:
row.SetValue(idfield, featid)
rows.insertrow(row)
partarray.removeall()
pntarray.removeall()
#adds parts and/or interior rings to the part array
elif (len(values) == 2 and float(values[1]) > 0) or values[0].lower() == "interiorring":
partarray.add(pntarray)
pntarray.removeall()
#add points to the point array
elif len(values) > 2:
pnt = createPoint(pnt, values)
pntarray.add(pnt)
elif (len(values) == 2 and lineno == 2):
featid = int(values[0])
inputTxtFile.close()
del rows
del row
except Exception, ErrorDesc:
# handle the errors here. if the point creation fails, want to keep track of which point failed (easier to fix the
# text file if we do)
if ErrorDesc[0] == msgErrorCreatingPoint:
if inDataType.lower() == "point":
msgErrorCreatingPoint = msgErrorCreatingPoint % (values[0], values[0])
else:
msgErrorCreatingPoint = msgErrorCreatingPoint % (values[0], featid)
gp.AddError(msgErrorCreatingPoint)
elif ErrorDesc[0] != "":
gp.AddError(str(ErrorDesc))
gp.AddError(gp.getmessages(2))
# make sure to close up the fileinput no matter what.
if inputTxtFile: inputTxtFile.close()
Additional search keys: doughnut, polygon rings, writing polygon geometry