ArcMap

Identity

Available with Advanced license.

Summary

Computes the geometric intersection of two coverages. All features of the input coverage, as well as those features of the identity coverage that overlap the input coverage, are preserved in the output coverage.

Learn more about how Identity works

Illustration

Identity illustartion

Usage

  • The identity coverage must have polygon topology.

  • The input coverage, identity coverage, and output coverage must have different names, even when in different workspaces.

  • Route systems in the input coverage are maintained in the output coverage. However, IDENTITY on routes and sections themselves are not permitted.

  • Region subclasses from both input coverage and identity coverage are maintained with the POLY option. Subclasses with identical names and attribute schemas are appended. Output regions are clipped by the extent of the output coverage.

  • Label points are generated in each output coverage polygon when the POLY option is used. The new polygon User-IDs are set equal to the polygon internal number minus one. When the LINE option is used, User-IDs of the input coverage are maintained.

  • Annotation is copied from input coverage and saved in output coverage.

  • The coordinate precision of the output coverage is determined by the Precision for Derived Coverages environment.

  • Projection files will be compared for similarity using the level of comparison specified in the Compare Projections environment.

  • The output coverage inherits the items from the point attribute table, tics, and the projection file data model contents from the input coverage.

  • When the input coverage contains linear data belonging to different planar graphs, the data will be maintained in the output coverage. For example, with coincident or colinear arcs, such as arcs representing utility cables at different levels or a road following a stream, the coincident and colinear line segments will be preserved. However, additional vertices may be inserted. In the case of intersecting arcs, such as a road passing over a stream, nodes will not be inserted at the apparent intersection.

Syntax

arcpy.arc.Identity(in_cover, identity_cover, out_cover, {feature_type}, {fuzzy_tolerance}, {join_attributes})
ParameterExplanationData Type
in_cover

The coverage that will be overlaid with the identity coverage.

Coverage
identity_cover

The coverage that will be identitied with the input coverage. Must have polygon features.

Coverage
out_cover

The coverage to be created.

Coverage
feature_type
(Optional)

The feature class from the input coverage that will be used.

  • POLY —Poly on poly overlay. This is the default option.
  • LINE —Line on poly overlay.
  • POINT —Point on poly overlay.
String
fuzzy_tolerance
(Optional)

The minimum distance between coordinates in the output coverage. By default, the minimum fuzzy tolerance value from the input and erase coverages is used.

Learn more about how the default fuzzy tolerance is calculated

Double
join_attributes
(Optional)

Specifies whether all items in both the input coverage feature attribute and identity coverage will be joined to the output coverage feature attribute table.

  • JOIN —All feature attribute items from both coverages will appear in the output coverage feature attribute table. If a duplicate item is encountered, the item in the input coverage will be maintained and the one in the join file will be dropped. This is the default option.
  • NO_JOIN —Only the feature's internal number (cover#) from the input coverage and the intersect coverage are joined in the output coverage feature attribute table. This option is useful in reducing the size of the output coverage feature attribute table. The Add Join tool can then be used to get the attributes to the output coverage features.
Boolean

Code sample

Identity example (stand-alone script)

The following stand-alone script demonstrates how to split roads where they pass through city boundaries.

# Name: Identity_Example.py
# Description: Splits roads where they pass through city boundaries.
# Requirements: ArcInfo Workstation

# Import system modules
import arcpy
from arcpy import env

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

# Set local variables
inCover = "major_rds"
identityCover = "citylim"
outCover = "C:/output/major_roads"
featureType = "LINE"

# Execute Identity
arcpy.Identity_arc(inCover, identityCover, outCover, featureType, "", "")

Environments

Licensing information

  • Basic: No
  • Standard: No
  • Advanced: Requires ArcInfo Workstation installed

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