ArcMap

Calculate Polygon Main Angle

Summary

Calculates the dominant angles of input polygon features and assigns the values to a specified field in the feature class.

Usage

  • The dominant angle of a polygon is the angle of longest collection of segments that have similar orientation. This angle will be stored in the specified field in decimal degrees from true north.

  • Use this tool to determine the trend of a polygon and use the resulting angle to orient symbology such as markers or hatch lines within the polygon. This tool is meant for primarily orthogonal polygons rather than organically shaped ones.

Syntax

arcpy.cartography.CalculatePolygonMainAngle(in_features, angle_field, {rotation_method})
ParameterExplanationData Type
in_features

The input polygon features.

Feature Layer
angle_field

The field that will be updated with the polygon main angle values.

Field
rotation_method
(Optional)

Controls the method and origin point of rotation.

  • GEOGRAPHIC —Angle is calculated clockwise with 0 at top/north.
  • ARITHMETIC —Angle is calculated counterclockwise with 0 at the right/east.
  • GRAPHIC —Angle is calculated counterclockwise with 0 at top/north. This is the default.
String

Derived Output

NameExplanationData Type
out_features

The updated input polygon features.

Feature Layer

Code sample

CalculatePolygonMainAngle example 1 (Python window)

The following Python window script demonstrates how to use the CalculatePolygonMainAngle tool in immediate mode.

import arcpy
arcpy.env.workspace = "C:\data"
arcpy.CalculatePolygonMainAngle_cartography("cities", "poly_angle", "GEOGRAPHIC")
CalculatePolygonMainAngle example 2 (stand-alone script)

This stand-alone script shows an example of using the CalculatePolygonMainAngle tool.

# Name: CalculatePolygonMainAngle_standalone_script.py
# Description: calculates an angle for a polygon based on the largest edge of the feature
 
# Import system modules
import arcpy
from arcpy import env

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

# Set local variables
in_features = "cities"
angle_field = "poly_angle"
rotation_method = "ARITHMETIC"

# Execute Calculate Polygon Main Angle
arcpy.CalculatePolygonMainAngle_cartography(in_features, angle_field, rotation_method)

Environments

Licensing information

  • Basic: No
  • Standard: Yes
  • Advanced: Yes

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