Generate Origin-Destination Links (Analysis)

Summary

Generates connecting lines from origin features to destination features. This is often referred to as a spider diagram.

Illustration

Generate Origin Destination Links

Usage

  • When the origin or destination features are lines or polygons, the feature centroids are used for generating links.

  • The output features will include the following attribute fields:

    • ORIG_FID—The ObjectID field of the origin feature.
    • ORIG_X—The x-coordinate of the origin feature (or centroid).
    • ORIG_Y—The y-coordinate of the origin feature (or centroid).
    • DEST_FID—The ObjectID field of the destination feature.
    • DEST_X—The x-coordinate of the destination feature (or centroid).
    • DEST_Y—The y-coordinate of the destination feature (or centroid).
    • LINK_DIST—The length of the output link, measured in the specified distance unit.
    • GROUP_ID—The group field values that are shared between linked pairs of origin and destination features. This field will only be added if both origin and destination group fields are specified.
    • COLOR_ID—A numeric value that is used to symbolize origins or groups into at most eight unique colored links. The values are random numbers between 1 and 8.
    • LINK_COUNT—The number of overlapping links. This is added when you specify to aggregate overlapping links.
    • Any statistics fields specified when aggregating overlapping links will also be added to the output feature class.

  • The origin features and destination features can be specified as the same layer or dataset. If the same data is used for origins and destinations, links will not be generated from an origin to the destination feature with the same Object ID, as this zero-length line is a null geometry error.

  • This tool can be used for both one-to-one and one-to-many relationships. For example, you can link a motor vehicle theft to its recovery location (one-to-one), or perform a proximity analysis to understand the distances between a central headquarters location to several regional office locations (one-to-many).

  • The output links layer will include the following charts to help you visualize the result of the analysis:

    • A bar chart of the count of each group ID, if you specified group fields.
    • A bar chart of the sum of link lengths for each origin ID or group ID (if you specified group fields). This is useful to see if some origins or groups have large or small total distances to destinations.
    • A bar chart of the mean link lengths for each origin ID or group ID (if you specified group fields). This is useful to see the average distance between origin features or groups and their linked destinations.
    • A box plot of the distribution of link lengths for each origin ID or group ID (if you specified group fields). This is useful to see if most of the links for an origin or group have small or large lengths to their destinations, and the range and distribution summary of those link lengths. If an origin ID or group ID has a vertically short box, it means the distances from that origin or group to all linked destinations were similar. If an origin ID or group ID has a box that is located high on the y-axis, most of the links have a long length.

Syntax

GenerateOriginDestinationLinks(origin_features, destination_features, out_feature_class, {origin_group_field}, {destination_group_field}, {line_type}, {num_nearest}, {search_distance}, distance_unit, {aggregate_links}, {sum_fields})
ParameterExplanationData Type
origin_features

The input features from which links will be generated.

Feature Layer
destination_features

The destination features to which links will be generated.

Feature Layer
out_feature_class

The output polyline feature class that will contain the output links.

Feature Class
origin_group_field
(Optional)

The attribute field from the input origin features that will be used for grouping. Features that have the same group field value between origins and destinations will be connected with a link.

Field
destination_group_field
(Optional)

The attribute field from the input destination features that will be used for grouping. Features that have the same group field value between origins and destinations will be connected with a link.

Field
line_type
(Optional)

Specifies whether a shortest path on a spheroid (geodesic) or a Cartesian projected earth (planar) will be used when generating the output links. Geodesic lines will have a slight curve when their length exceeds approximately 50 kilometers, as the curvature of the Earth makes the shortest distance between two points appear curved when viewed on a 2D map.

It is recommended that you use the Geodesic line type with data stored in a coordinate system that is not appropriate for distance measurements (for example, Web Mercator and any geographic coordinate system) or any dataset that spans a large geographic area.

  • PLANARPlanar distance will be used between features. This is the default.
  • GEODESICGeodesic distances will be used between features. This line type takes into account the curvature of the spheroid and correctly deals with data near the dateline and poles.
String
num_nearest
(Optional)

The maximum number of links that will be generated per origin feature to the nearest destination features. If no number is specified, the tool will generate links between all origin and destination features.

For example, using a value of 1 will generate links between each origin feature and its closest destination feature.

Double
search_distance
(Optional)

The maximum distance between an origin and destination feature that will produce a link feature in the output. The unit of the search distance is specified in the distance unit parameter. If no search distance is specified, the tool will generate links between all origin and destination features regardless of their distance apart.

Double
distance_unit

Specifies the units used to measure the length of the links. Distances for each link will appear in the LINK_DIST field. If a distance unit is not specified, the distance unit of the origin features' coordinate system will be used.

  • KILOMETERSThe distance between origin and destination will be calculated in kilometers.
  • METERSThe distance between origin and destination will be calculated in meters.
  • MILESThe distance between origin and destination will be calculated in miles.
  • NAUTICALMILESThe distance between origin and destination will be calculated in nautical miles.
  • YARDSThe distance between origin and destination will be calculated in yards.
  • FEETThe distance between origin and destination will be calculated in feet.
String
aggregate_links
(Optional)

Specifies whether overlapping links will be aggregated.

  • AGGREGATE_OVERLAPPINGOverlapping links will be aggregated if the starting point coordinates are the same.
  • NO_AGGREGATEOverlapping links will not be aggregated. This is the default.
Boolean
sum_fields
[sum_fields,...]
(Optional)

Specifies numeric fields from the destination features containing attribute values that will be summarized when multiple links overlap. Multiple statistic and field combinations can be specified. Null values are excluded from all statistical calculations.

The available statistics types are as follows:

  • SUM—Add the total value for the specified field.
  • MEAN—Calculate the average for the specified field.
  • MIN—Find the smallest value of all records for the specified field.
  • MAX—Find the largest value of all records for the specified field.
  • RANGE—Find the range of values (maximum minus minimum) for the specified field.
  • STD—Find the standard deviation of values for the specified field.
  • COUNT—Find the number of values included in statistical calculations. This counts each value except null values. To determine the number of null values in a field, create a count for the field in question, create a count for a different field that does not contain null values (for example, the OID if present), and subtract the field with null values from the field without null values.
  • FIRST—Find the first record in the input and use its specified field value.
  • LAST—Find the last record in the input and use its specified field value.
  • MEDIAN—Calculate the median of all records for the specified field.
  • VARIANCE—Calculate the variance of all records for the specified field.
  • UNIQUE—Count the number of unique values for the specified field.
Value Table

Code sample

GenerateOriginDestinationLinks example 1 (Python window)

The following demonstrates how to use the GenerateOriginDestinationLinks function in the Python window:

import arcpy
arcpy.env.workspace = "C:/data/input/genODLinks.gdb"

arcpy.GenerateOriginDestinationLinks_analysis(
    "Station_100", "City_FireResponses", "Station_100_OD_Links")
GenerateOriginDestinationLinks example 2 (stand-alone script)

The following Python script demonstrates how to use the GenerateOriginDestinationLinks function in a stand-alone script:

# Name: GenerateODLinks.py
# Description: Finds 10 nearest links within 25 miles from the origin fire
#              stations to the destination response points.

# import system modules
import arcpy

# set workspace environment
arcpy.env.workspace = "C:/data/input/genODLinks.gdb"

# set required parameters 
origin_features = "Station_100"
destination_features = "City_FireResponses"
out_feature_class = "Station_100_OD_Links"

# optional parameters
origin_group_field = 'STA_NUM'
destination_group_field = 'District'
line_type = 'PLANAR'
num_nearest = 10
search_distance = 25
distance_unit = 'MILES'
aggregate_links='AGGREGATE_OVERLAPPING'
sum_fields = 'TimeSpentOnCall SUM'

# make links between fire stations and call response points
arcpy.GenerateOriginDestinationLinks_analysis(
    origin_features, destination_features, out_feature_class,
    origin_group_field, destination_group_field, line_type, num_nearest,
    search_distance, distance_unit, aggregate_links, sum_fields)

Licensing information

  • Basic: Yes
  • Standard: Yes
  • Advanced: Yes

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