Z Score Rendering (Spatial Statistics)

Usage tips

• The Z Renderer creates a layer file with z scores rendered in the following manner:

  Z scores below – 2 standard deviations are rendered dark blue.
  Z scores between – 2 and – 1 standard deviations are light blue.
  Z scores between – 1 and +1 standard deviations are neutral.
  Z scores between 1 and 2 standard deviations are pink.
  Z scores above 2 standard deviations are bright red.

• The Z Renderer is appropriate for rendering output from both Hot Spot Analysis and Cluster and Outlier Analysis tools.

• This tool will only work on the windows operating system.

• The environment settings do not affect this tool.

Command line syntax
An overview of the Command Line window
ZRenderer_stats <Input_Feature_Class> <Field_to_Render> <Output_Layer_File>

Command line example

workspace e:\project93\data
HotSpot tracts.shp AGE_65_UP tract65.shp 'Inverse Distance' 'Euclidean Distance' 0 None ZRenderer tract65.shp GiInvDst tracthot

Scripting syntax
About getting started with writing geoprocessing scripts
ZRenderer_stats (Input_Feature_Class, Field_to_Render, Output_Layer_File)

Script example

# Perform Hot Spot Analysis for assault incidents
# Import system modules
import arcgisscripting

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

# Local variables...
workspace = "C:/project93/data"
input = "assaults.shp"
collect_output = "collect_output.shp"
collect_count_field = "Count"
hotspot_output = "hotspot_output.shp"
hotspot_output_rendered = "hotspot_output_rendered.lyr"
z_score_field_name = "GiInvDst"

try:
    # Set the current workspace (to avoid having to specify the full path to the feature classes each time)
    gp.workspace = workspace

    # Convert assault incidents into weighted point data
    # Process: Collect Events...
    gp.CollectEvents_stats(input, collect_output)

    # Calculate Getis-Ord Gi* statistic
    # Process: Hot Spot Analysis (Getis-Ord Gi*)...
    gp.HotSpots_stats(collect_output, collect_count_field, hotspot_output, "Inverse Distance", "Euclidean Distance", "None", "#", "#", "#")

    # Render hot spot analysis
    # Process: Z Score Rendering...
    gp.ZRenderer_stats(hotspot_output, z_score_field_name, hotspot_output_rendered)

except:
    # If an error occurred when running the tool, print out the error message.
    print gp.GetMessages(2)