Desktop Help 10.0 - Frequency (Analysis)

Summary

Reads a table and a set of fields and creates a new table containing unique field values and the number of occurrences of each unique field value.

Usage

The output table will contain the field Frequency and the specified frequency field(s) and summary field(s).
The output table will contain the frequency calculation for each attribute value combination of the specified frequency field(s).
If a summary field is specified, the unique attribute values of the frequency calculation are summarized by the numeric attribute values of each summary field.
When using layers, only the currently selected features are used in calculations.

Syntax

Frequency_analysis (in_table, out_table, frequency_fields, {summary_fields})

Parameter	Explanation	Data Type
in_table	The table containing the field(s) that will be used to calculate frequency statistics. This table can be an INFO or OLE DB table, a dBASE or a VPF table, or a feature class table.	Table View; Raster Layer
out_table	The table that will store the calculated frequency statistics.	Table
frequency_fields [frequency_fields,...]	The attribute field or fields that will be used to calculate frequency statistics.	Field
summary_fields [summary_fields,...] (Optional)	The attribute field or fields to sum and add to the output table. Null values are excluded from this calculation.	Field

Code Sample

Frequency Example (Python Window)

The following Python window script demonstrates how to use the Frequency function in immediate mode.

import arcpy
from arcpy import env
env.workspace = "C:/data/Portland.gdb/Taxlots"
arcpy.Frequency_analysis("taxlots", "C:/output/output.gdb/tax_frequency",["YEARBUILT", "COUNTY"], ["LANDVAL", "BLDGVAL", "TOTALVAL"])

Frequency Example 2 (stand-alone script)

The following stand-alone script demonstrates how to use the Frequency function.

# Name: Frequency_Example2.py
# Description: Run Frequency on a table
# Author: ESRI
 
# Import system modules
import arcpy
from arcpy import env
 
# Set environment settings
env.workspace = "C:/data/Portland.gdb/Taxlots"
 
# Set local variables
inTable = "taxlots"
outTable = "C:/output/output.gdb/tax_frequency"
frequencyFields = ["YEARBUILT", "COUNTY"]
summaryFields = ["LANDVAL", "BLDGVAL", "TOTALVAL"]
 
# Execute Frequency
arcpy.Frequency_analysis(inTable, outTable, frequencyFields, summaryFields)

Frequency Example 3 (stand-alone script)

The following stand-alone script demonstrates how to use many geoprocessing scripting functions, including the Frequency function.

# Name: Frequency_Example3.py
# Description: Break all multipart features into singlepart features, 
#  and generate a report of which features were separated.
# Author: ESRI
 
# Import system modules
import arcpy
from arcpy import env
 
# Create variables for the input and output feature classes
inFeatureClass = "c:/gdb.mdb/vegetation"
outFeatureClass = "c:/gdb.mdb/vegetation_singlepart"
 
# Use error trapping in case a problem occurs when running the tools
try:
    # Add a field to the input (if not already present), this will be used as a unique identifier
    # Create list of all fields in inFeatureClass
    fieldList = arcpy.ListFields(inFeatureClass)
    # Create new empty list to hold field names from inFeatureClass
    fieldNameList = []
    # polulate the field name list with field names from inFeatureClass 
    for field in fieldList:
        fieldNameList = fieldNameList.append(field.name)
    # if "tmpUID" is not a field name in inFeatureClass, add it
    if "tmpUID" not in fieldNameList:
        arcpy.AddField(inFeatureClass, "tmpUID","double")
 
    # Determine what the name of the Object ID is 
    describe = arcpy.Describe(inFeatureClass)  
    OidFieldName = describe.OIDFieldName
 
    # Calculate the tmpUID to the OID since this is a Personal GDB, wrap the Field inside []
    exp = "[" + OidFieldName + "]"
    arcpy.CalculateField_management(inFeatureClass, "tmpUID", exp)
 
    # Run the tool to create a new fc with only singlepart features
    arcpy.MultipartToSinglepart_management(inFeatureClass,outFeatureClass)
 
    # Check if there is a different number of features in the output than there was in the input 
    if (arcpy.GetCount_management(inFeatureClass) == (arcpy.GetCount_management(outFeatureClass)):
        print "The number of features in the input is the same as in the output, so no multipart features were found"
    else:
        # If there is a difference, print out the FID of the input features which were multipart
        arcpy.Frequency_analysis(outFeatureClass, outFeatureClass + "_freq", "tmpUID")
 
        # Use a search cursor to go through the table, and print the tmpUID 
        print "Below is a list of the FIDs of all the multipart features from " + inFeatureClass
        rows = arcpy.SearchCursor(outFeatureClass + "_freq", "[FREQUENCY] > 1")
        row = rows.next()
        while row:
            print int(row.tmpUID)
            row = rows.next()
 
except:
    # If an error occurred, print out the error message
    print "Error occurred"
    print arcpy.GetMessages()

Environments

Output CONFIG Keyword, Current Workspace, Scratch Workspace

Licensing Information

ArcView: No

ArcEditor: No

ArcInfo: Yes

4/4/2012