Clean (Coverage)

License Level:BasicStandardAdvanced


Generates a coverage with correct polygon or arc–node topology. To do this, Clean edits and corrects geometric coordinate errors, assembles arcs into polygons, and creates feature attribute information for each polygon or arc (that is, creates a PAT or AAT).

Learn more about how Clean works


Clean illustration



Clean_arc (in_cover, {out_cover}, {dangle_length}, {fuzzy_tolerance}, {feature_type})
ParameterExplanationData Type

The coverage to be cleaned.


The coverage created by Clean. If the Input Coverage and the Output Coverage have the same name, the Input Coverage will be replaced. By default, the Input Coverage is replaced.


The minimum length allowed for dangling arcs in the Output Coverage. A dangling arc is an arc that has the same polygon internal number on its left and right sides and ends at a dangling node. Dangling arcs are removed for both the POLY and LINE options. If the Dangle Length is not provided, the dangle length is read from the coverage TOL file if the TOL file exists;otherwise, dangle length is set to zero (the default).


The minimum distance between coordinates in each out_cover.

Learn more about how the default fuzzy tolerance is calculated


Specifies whether to create polygon topology and a PAT or arc–node topology and an AAT. POLY is the default option. If POLY is used on a coverage that has an existing AAT, Clean will also automatically rebuild the AAT.

  • POLYPolygon topology and a PAT are created. If POLY is used on a coverage that has an existing AAT, Clean will also automatically rebuild the AAT. POLY is the default option.
  • LINEArc–node topology and an AAT are created.

Code Sample

Clean example (stand-alone script)

The following stand-alone script demonstrates how to clean a coverage for polygon topology.

# Name:
# Description: Cleans a coverage for polygon topology.
# Requirements: ArcInfo Workstation

# Import system modules
import arcpy
from arcpy import env

# Set environment settings
env.workspace = "C:/data"

# Set local variables
inCover = "zones"
outCover = "C:/output/zones"
fuzzyTolerance = 0.25
featureType = "POLY"

#Execute Clean
arcpy.Clean_arc(inCover, outCover, "", fuzzyTolerance, featureType)


Related Topics

Licensing Information

ArcGIS for Desktop Basic: No
ArcGIS for Desktop Standard: No
ArcGIS for Desktop Advanced: Requires ArcInfo Workstation installed