Directional Distribution (Standard Deviational Ellipse) (Spatial Statistics)

Measures whether a distribution of features exhibits a directional trend (whether features are farther from a specified point in one direction than in another direction).

Learn about how Directional Distribution: Standard Deviational Ellipse works


Illustration

Directional Distribution (Standard Deviational Ellipse) illustration

Usage tips

Syntax

DirectionalDistribution_stats (Input_Feature_Class, Output_Ellipse_Feature_Class, Ellipse_Size, Weight_Field, Case_Field)
Parameter Explanation Datatype
Input Feature Class (Required)

A feature class containing a distribution of features for which the standard deviational ellipse will be calculated.

Feature Layer
Output Ellipse Feature Class (Required)

A polygon feature class that will contain the output ellipse feature.

Feature Class
Ellipse Size (Required)

The size of output ellipses in standard deviations. The default ellipse size is 1; valid choices are 1, 2, or 3 standard deviations.

String
Weight Field (Optional)

The numeric field used to weight locations according to their relative importance.

Field
Case Field (Optional)

Field used to group features for separate directional distribution calculations. The case field can be of numeric, date, or string type.

Field
Data types for geoprocessing tool parameters

Script Example

# Measure the geographic distribution of auto thefts

# Import system modules
import arcgisscripting

# Create the Geoprocessor object
gp = arcgisscripting.create()

# Local variables...
workspace = "C:/chris/data/"
auto_theft_locations = "AutoTheft.shp"
auto_theft_links = "AutoTheft_links.shp"
auto_theft_sd = "auto_theft_SD.shp"
auto_theft_se = "auto_theft_SE.shp"
auto_theft_ldm = "auto_theft_LDM.shp"

try:
    # Set the workspace (to avoid having to type in the full path to the data every time)
    gp.Workspace = workspace

    # Process: Standard Distance of auto theft locations...
gp.StandardDistance_stats(auto_theft_locations, auto_theft_sd, "1 Standard Deviation", "#", "#") # Process: Directional Distribution (Standard Deviational Ellipse) of auto theft locations... gp.DirectionalDistribution_stats(auto_theft_locations, auto_theft_se, "1 Standard Deviation", "#", "#") # Process: Linear Directional Mean of auto thefts... gp.DirectionalMean_stats(auto_theft_links, auto_theft_ldm, "false", "#") except: # If an error occurred while running a tool, print the messages print gp.GetMessages()

See Also

  • Central Feature (Spatial Statistics)
  • Mean Center (Spatial Statistics)
  • Standard Distance (Spatial Statistics)