ArcMap

Symbolize by Dot Density

Available with Business Analyst license.

Summary

Thematically maps a feature class based on a numeric field as dots on the map to convey the intensity of an attribute.

Usage

  • This is a type of thematic map in which a certain number of dots are used to represent a numeric attribute associated with a polygon layer.

  • When selecting the dot size, keep a perspective on the data you are symbolizing. For example, selecting a dot size of 10 based on total population per county would result in a map that would be mostly black, since the dot distribution would be too dense to visualize. A better choice would be to select a dot size of 100 or 1,000 to better see the distribution of population.

  • The dots are evenly distributed across each polygon in your feature class.

Syntax

SymbolizeByDotDensity(InputFeatureLayer, Field, DotSizeParameterName, ColorParameterName, {UseSelectedFeatures})
ParameterExplanationData Type
InputFeatureLayer

The input feature layer.

Feature Layer
Field

The attribute field used to define the thematic map.

String
DotSizeParameterName

The numeric value that represents the field selection to be symbolized.

Double
ColorParameterName

The color assigned to the points to be symbolized.

Long
UseSelectedFeatures
(Optional)

Identifies the features that will be used to generate the thematic map.

  • TRUE —Uses only selected features to generate the thematic map.
  • FALSE —Uses all features to generate the thematic map. This is the default.
Boolean

Code sample

SymbolizeByDotDensity example (stand-alone script)

# Name: SymbolizeByDotDensity.py
# Description: Symbolizes block groups by dot density using total population.
# Author: Esri

# Import system modules
import arcview
import arcpy

arcpy.ImportToolbox(r"C:\Program Files (x86)\ArcGIS\Desktop10.8\Business Analyst\ArcToolbox\Toolboxes\Business Analyst Tools.tbx")

try:
# Acquire extension license 
  arcpy.CheckOutExtension("Business")
 
# Defines the parameters for the Symbolize by Dot Density tool
# Red point is -65536
  InputFeatureLayer = "C:/ArcGIS/Business Analyst/US_2019/Data/Demographic Data/BlockGroups_bg.bds"
  Field = "TOTPOP_CY"
  DotSizeParameterName = 10
  ColorParameterName = -65536
 
# Thematically symbolizes a polygon layer by dot density
  arcpy.SymbolizeByDotDensity_ba(InputFeatureLayer, Field, DotSizeParameterName, ColorParameterName)
 
# Release extension license 
  arcpy.CheckInExtension("Business") 
 
except:
  print arcpy.GetMessages(2)

Environments

This tool does not use any geoprocessing environments.

Licensing information

  • Basic: Requires Business Analyst
  • Standard: Requires Business Analyst
  • Advanced: Requires Business Analyst

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