Letter Intersections (Defense)

Summary

Identifies intersections in a line feature class and adds sequential letters to output point features.

Usage

• When naming a new field to letter in the Field to Letter (New Field Name) parameter, the first letter must be an alpha character, and the remaining letters must be alphanumeric or underscores.

Parameters

Dialog

Label	Explanation	Data Type
Input Line Features	The input line features with intersections that will be lettered.	Feature Set
Output Intersection Points Feature Class	The output point feature class.	Feature Class
Field to Letter (New Field Name)	The name of the field that will contain the letter designator for each intersection.	Field
Input Area to Letter (Optional)	The area that will limit the intersections identified; only intersections within this area will be identified and lettered.	Feature Set
Spatial Sort Method (Optional)	Specifies how features will be spatially sorted for the purpose of lettering. Features are not reordered in the table. Upper right—Features will be sorted starting at the upper right corner. This is the default. Upper left—Features will be sorted starting at the upper left corner. Lower right—Features will be sorted starting at the lower right corner. Lower left—Features will be sorted starting at the lower left corner. Peano curve—Features will be sorted using a space-filling curve algorithm, also known as a Peano curve. Center—Features will be sorted starting from a center point (the mean center will be used if no center is provided). Clockwise—Features will be sorted starting from a center point and moving clockwise. Counterclockwise—Features will be sorted starting from a center point and moving counterclockwise. None—No spatial sort will be used. The same order as the feature class will be used.	String
Lettering Format (Optional)	Specifies the labeling format that will be used for each feature. Excel (A, B, C, ...)—An alpha character (for example, A, B, C) will be used. This is the default. Grid (AA, AB, AC, ...)—A constant alpha character with an incrementing second alpha character grid (for example, AA, AB, AC) will be used. Alternating Grid (AA, BB, CC, ...)—A double alpha character that is incremented for each feature (for example, AA, BB, CC) will be used.	String
Starting Letter (Optional)	The value that will be used to begin lettering.	String
Omit Letters (Optional)	The values that will be omitted from the lettering sequence.	String
Minimum Distance Between Output Points (Optional)	The minimum distance between intersections that are identified for lettering.	Linear Unit
Center Point (Optional)	The center point that will be used to sort and letter features.	Feature Set
Add Distance and Bearing to Center (Optional)	Specifies whether fields will be added to the output for distance and bearing to a center point. Do not add distance and bearing—No distance or bearing fields will be added to the output. This is the default. Add distance and bearing—DIST_TO_CENTER and ANGLE_TO_CENTER fields will be added to the output.	Boolean

Python

arcpy.defense.LetterIntersections(in_features, out_feature_class, field_to_letter, {in_area}, {spatial_sort_method}, {lettering_format}, {starting_letter}, {omit_letters}, {min_out_point_distance}, {center_point}, {add_distance_and_bearing})

Name	Explanation	Data Type
in_features	The input line features with intersections that will be lettered.	Feature Set
out_feature_class	The output point feature class.	Feature Class
field_to_letter	The name of the field that will contain the letter designator for each intersection.	Field
in_area (Optional)	The area that will limit the intersections identified; only intersections within this area will be identified and lettered.	Feature Set
spatial_sort_method (Optional)	Specifies how features will be spatially sorted for the purpose of lettering. Features are not reordered in the table. UR—Features will be sorted starting at the upper right corner. This is the default. UL—Features will be sorted starting at the upper left corner. LR—Features will be sorted starting at the lower right corner. LL—Features will be sorted starting at the lower left corner. PEANO—Features will be sorted using a space-filling curve algorithm, also known as a Peano curve. CENTER—Features will be sorted starting from a center point (the mean center will be used if no center is provided). CLOCKWISE—Features will be sorted starting from a center point and moving clockwise. COUNTERCLOCKWISE—Features will be sorted starting from a center point and moving counterclockwise. NONE—No spatial sort will be used. The same order as the feature class will be used.	String
lettering_format (Optional)	Specifies the labeling format that will be used for each feature. A_B_C—An alpha character (for example, A, B, C) will be used. This is the default. AA_AB_AC—A constant alpha character with an incrementing second alpha character grid (for example, AA, AB, AC) will be used. AA_BB_CC—A double alpha character that is incremented for each feature (for example, AA, BB, CC) will be used.	String
starting_letter (Optional)	The value that will be used to begin lettering.	String
omit_letters [omit_letters,...] (Optional)	The values that will be omitted from the lettering sequence.	String
min_out_point_distance (Optional)	The minimum distance between intersections that are identified for lettering.	Linear Unit
center_point (Optional)	The center point that will be used to sort and letter features.	Feature Set
add_distance_and_bearing (Optional)	Specifies whether fields will be added to the output for distance and bearing to a center point. DONT_ADD_DISTANCE—No distance or bearing fields will be added to the output. This is the default. ADD_DISTANCE—DIST_TO_CENTER and ANGLE_TO_CENTER fields will be added to the output.	Boolean

Code sample

LetterIntersections example 1 (Python window)

The following Python window script demonstrates how to use the LetterIntersections function.

import arcpy
arcpy.env.workspace = r"C:/data.gdb"
arcpy.defense.LetterIntersections("streets", "intersections", "intersection_id")

LetterIntersections example 2 (stand-alone script)

The following example uses the LetterIntersections function in an example workflow script.

# Find intersections, assign a unique value, and create a buffer.

# Import system modules
import arcpy

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

# Find intersections
input_lines = "Streets"
output_intersections = "intersection_subset"
arcpy.defense.LetterIntersections(input_lines,
                                  output_intersections,
                                  "intersection_id",
                                  "aoi",
                                  "UL",
                                  "A_B_C",
                                  "A",
                                  "L;O",
                                  None,
                                  "ADD_DISTANCE")

# Create buffers
arcpy.analysis.Buffer(output_intersections,
                      "intersection_buffers",
                      "40 Feet")

Environments

Extent, Current Workspace, Scratch Workspace