Available with Spatial Analyst license.

Calculates percentage of total population living within or near a zone for each reporting unit polygon and creates an output table.

Counts for the total population in the reporting unit and within the zone are also reported.

• This tool processes all polygons in the Reporting unit feature regardless of selections set. The ability to limit calculations to only selected reporting unit polygons is not supported in this release.

• NOTE: For the most accurate results and shortest processing times, it is highly recommended that all input layers be in the same spatial reference.

• NOTE: Enabling the Parallel Processing Factor environment can improve computation time for several ATtILA tools, but we have detected, on rare occasions, doing so can lead to spurious results. As a precaution, ATtILA will disable the Parallel Processing Factor environment for this tool. We hope to return this choice to the user once the impact on operational speed and accuracy of swapping geoprocessing tools with their pairwise counterparts has been assessed.

• The Reporting unit feature is a zone dataset.

  • A zone is defined as all areas in the input that have the same value. The areas do not have to be contiguous. The term "value" in this definition refers to the unique values in the Reporting unit ID field. Therefore, all polygons with the same reporting unit ID are treated as a single zone.

  • When more than one polygon has the same reporting unit ID, the areas for each polygon are combined and metrics are reported as a single record in the Output table.

• As the Reporting unit feature is a vector dataset, ArcGIS will perform a vector to raster conversion during processing.

  • To better control the vector to raster conversion, the tool defaults the Snap raster and the Processing cell size to that of the Land cover grid. These may be changed from within the tool.

  • If a large size disparity exists between the extents of the Reporting unit feature and the Land cover grid, the user may wish to set the Extent in Environment Settings > Processing Extent to the smaller of the two to avoid unnecessary processing.

• If the Reporting unit feature has overlapping features, the zonal analysis will be performed for each individual feature.

• If a feature in the Reporting unit feature zone data does not overlap any cell centers in the secondary class rasters (e.g.,Land cover grid), those zones will not get converted to the internal zone raster. As a result, those zones will not be represented in the Output table.

• Final output is written to the location specified in the Output table parameter. The Output table may be saved as a File Geodatabase Table, or a dBASE Table.

  • NOTE: For most consistent results, it is highly recommended that tool output be saved to a file geodatabase.

  • When saving as a File Geodatabase Table, no extension is necessary for the Output table name. The output location must be a file geodatabase.

  • When saving as a dBASE Table, include the .dbf extension in the Output table name. dBASE tables may not be saved in a file geodatabase.

• When the optional PER CAPITA (square meters of land cover type per individual) selection is checked, the tool allows the user to select a Population raster or polygon feature and a corresponding Population field.

  • The Population raster or polygon feature will allow you to choose either a raster, or a polygon feature.

    • When choosing a raster, this tool assumes the grid cell value to be the population count for the grid cell.

    • When choosing a polygon feature, this tool assumes that population is distributed evenly throughout each feature polygon. The tool apportions population by area weighting. For example, if 50% of a population polygon is within a reporting unit, the tool will assign 50% of the value in the polygon's Population field to that reporting unit. Caution should be exercised when population polygons do not have even population distributions as this could result in an overweighting or underweighting of population when the tool performs the apportionment. Generally, greater accuracy will be achieved if the population polygons are smaller than the smallest Reporting unit feature polygons.

    • NOTE: The Population field dropdown is only available when the Population raster or polygon feature is a polygon feature.

    • NOTE: The Population field will default to 'Value' when the Population raster or polygon feature is an integer grid.

    • NOTE: The Population field will be empty when the Population raster or polygon feature is a non-integer grid.

• Field names in the Output table are as follows:

  • RU_POP - The population for the reporting unit.

  • ZN_POP_C - The population in a zone for the reporting unit.

  • ZN_POP_P - The percentage of the reporting unit population in a zone.

• In Additional Options, the user may elect to 'Retain Intermediate Layers Generated During Metric Processing', and/or 'Record Process Steps Taken During Metric Calculation'.

  • Retain Intermediate Layers Generated During Metric Calculation

    • Choosing INTERMEDIATES retains several of the key intermediate products (e.g., rasters, feature classes, tables) used to generate the final tool output. By examining the intermediate products, the user can gain a better understanding how the metric is calculated. The following intermediate products are listed in the general order they are generated:

      • pwzm_[Zone raster or vector feature]_Buffer_# (vector) - Zone raster or vector feature buffered to the Buffer distance. The attribute table will contain fields from Zone raster or vector feature, the buffer distance (BUFF_DIST), and a field named, 'ORIG_FID'. This feature class is only produced when the Zone raster or vector feature is a vector feature.

      • pwzm_populationCnt# (table) - A table with the population count within each reporting unit.

        • If the Population raster or polygon feature is a polygon feature, the table is generated by performing a Tabulate Intersection operation using the Reporting unit feature as the Input Zone Feature, the Reporting unit ID field as the Zone Field, and the lcp_[Population polygon feature]# as the Input Class Features.

        • If the Population raster or polygon feature is a raster, the table is generated by performing a Zonal Statistics as Table operation using the Reporting unit feature as the Input raster or feature zone data, the Reporting unit ID field as the Zone field, and the Population raster or polygon feature as the Input value raster. The statistics type is "Sum" and the Ignore NoData in calculations is checked.

      • pwzm_[Population raster or polygon feature]_Work_# (vector) - A copy of the Population raster or polygon feature with the Population field retained and a tmpClass field added to assist in the population calculations via a Tabulate Intersection operation. This feature class is only produced when a polygon population feature is selected.

      • pwzm_[Zone raster or vector feature]_Work_# (vector) - A copy of the Zone raster or vector feature with a tmpClass field added to assist in the population calculations via a Tabulate Intersection operation. This feature class is only produced when both population and zone input features are vector datasets.

      • pwzm_[Zone raster or vector feature]_Poly_# (vector) - A polygon feature class produced by setting 0-value areas in the input zone raster to NULL and then performing a raster to polygon conversion. A tmpClass field is added to assist in the population calculations via a Tabulate Intersection operation This feature class is only produced when the Zone raster or vector feature is a raster.

      • pwzm_[Zone raster or vector feature]_Dissolve_# (vector) - A polygon feature class produced by dissolving pwzm_[Zone raster or vector feature]_Poly_# on the tmpClass field. This feature class is only produced when the Zone raster or vector feature is a raster. Produced only if the Zone raster or vector feature is a vector feature.

      • pwzm_[Zone raster or vector feature]_Identity_# (vector) - A feature class of the zone areas by reporting unit. This feature class is produced when at least one input is a vector feature.

        • if the Population input is a raster and the Zone input is a vector feature: This feature class is a copy of the Zone raster or vector feature with the overlying Reporting unit feature's ID attached via Identity.

        • if the Population input is a polygon feature and the Zone input is a raster: This feature class is a copy of the intermediate pwzm_[Zone raster or vector feature]_Poly# with the overlying Reporting unit feature's ID attached via Identity.

        • if the Population input is a polygon feature and the Zone input is a vector feature: This feature is a copy of the intermediate pwzm_[Zone raster or vector feature]_Work# with the overlying Reporting unit feature's ID attached via Identity.

      • pwzm_populationCnt#+1 (table) - A table with the population count within the zonal areas in each reporting unit.

        1. Raster Population and Raster Zone: this table is produced using a Zonal Statistics as Table operation with the Reporting unit feature as the in_zone_data, the Reporting unit ID field as the zone_field, the intermediate pwzm_populationFP as the in_value_raster, and 'Sum' as the statistics_type.

        2. Raster Population and Polygon Zone: this table is produced using a Zonal Statistics as Table operation with the intermediate pifm_[Floodplain polygon feature]_Identity# as the in_zone_data, the Reporting unit ID field as the zone_field, the Population raster as the in_value_raster, and 'Sum' as the statistics_type.

        3. Polygon Population and Raster Zone: this table is produced using a Tabulate Intersection operation using pifm_[Floodplain raster]_Identity# as the in_zone_features, Reporting unit ID field as the zone_field, pifm_[Population polygon feature]_Work# as the in_class_features, tmpClass as the class-fields, and Population field as the sum_fields.

        4. Polygon Population and Polygon Zone: this table is produced using a Tabulate Intersection operation using pifm_[Floodplain polygon feature]_Identity# as the in_zone_features, Reporting unit ID field as the zone_field, pifm_[Population polygon feature]_Work# as the in_class_features, tmpClass as the class-fields, and Population field as the sum_fields.

      • NOTE: To ensure unique filenames, intermediate filenames are typically generated using the CreateScratchName ArcPy function. This function provides a unique name for the intermediate product by appending a number to a filename prefix. The number starts at 0 and is incremented until a unique filename for the output workspace is found. The generated number is represented in this manual by the hashtag (#) symbol.

      • NOTE: The appended number may not be the same for all intermediate products saved during a tool run. Running a tool with different input options can result in different intermediate products being produced. If a tool is run more than once using the same output workspace, different number suffixes may be generated depending on the files already present in the output workspace.

    • Intermediate products are saved to one of the following locations:

      • When the Output table is saved as a File Geodatabase Table, intermediate products are placed in the same file geodatabase.

      • When the Output table is saved as a dBASE Table, a file geodatabase named "attilaScratchWorkspace" is automatically generated in the same output location specified for the Output table. Intermediate products are placed in the attilaScratchWorkspace file geodatabase.

      • NOTE: ATtILA will report the location of the saved intermediate products in the Tool Details' Messages section.

  • Record Process Steps Taken During Metric Calculation

    • Choosing LOGFILE will generate a text file containing information on system setup, tool inputs, parameter selections, script operations, and any encountered error or warning messages.

    • Log files will be named, [Output table]_[date_time].txt, with the date represented as YYYYMMDD and time as hh_mm_ss.

    • Where the log file is saved is dependent on the Current Workspace environment setting:

      • When the Current Workspace is a geodatabase, the log file will be located in the folder that contains that workspace.

      • When the Current Workspace is a folder, the log file will be located in that folder.

      • NOTE: In ArcGIS Pro, the default value for the Current Workspace environments is the project default geodatabase.

      • NOTE: ATtILA will report the name and location of the log file in the Tool Details' Messages section.

PAAA (Park_feature, {Dissolve_parks}, Cost_surface_raster, Population_raster_or_polygon_feature, {Population_field}, Maximum_travel_distance, Expand_area_served, Output_raster, {Processing_cell_size}, {Snap_raster}, {Select_options})

Population Within Zone Metrics example 1 (Python window)

This example returns a table with the population count in a reporting unit that is within 2000 meters of a daycare facility, the total population count within the reporting unit, and the percentage of the reporting unit's population that is in the 2000 meter buffer area. The options to retain the intermediate calculation products, and to record the process steps into a log file have also been selected.

import arcpy
from arcpy.sa import *
arcpy.ImportToolbox(r"D:\Destination Folder\ATtILA v{#}.tbx")

Reporting_unit_feature = "D:\\pyexamples\\data.gdb\\Blockgroups"
Reporting_unit_ID_field = "GEOID10"
Population_raster_or_polygon_feature = "D:\\pyexamples\\data.gdb\\Census2010"
Population_field = "TOTALPOP"
Zone_raster_or_polygon_feature = "D:\\pyexamples\\data.gdb\\Daycares"
Buffer_distance = "2000 Meters"
Group_by_zone = ""
Zone_ID_field = ""
Output_table = "D:\\pyexamples\\results.gdb\\Blockgroups_PWZM"
Select_options = "'INTERMEDIATES  -  Retain Intermediate Layers Generated During Metric Calculation';'LOGFILE  -  Record Process Steps Taken During Metric Calculation'" 

arcpy.ATtILA.PWZM(
                  Reporting_unit_feature,
                  Reporting_unit_ID_field,
                  Population_raster_or_polygon_feature,
                  Population_field,
                  Zone_raster_or_polygon_feature,
                  Buffer_distance,
                  Group_by_zone,
                  Zone_ID_field,
                  Output_table,
                  Select_options
                  ) 

Population Within Zone Metrics example 2 (Tool Details Messages)

This is a sample capture of the geoprocessing messages generated during a typical tool run. It is provided here to assist in the understanding of the tool's processing steps.

Start Time: Day, Month DD, YYYY hh:mm:ss AM/PM
Created log file: workspace path\\filename
Started: YYYY-MM-DD hh:mm:ss Setting up environment variables
Intermediates are stored in this directory: workspace path
[YYYY-MM-DD hh:mm:ss] Adding 2000 Meters buffer to Daycares. Intermediate: pwzm_Daycares_Buffer_0
[YYYY-MM-DD hh:mm:ss] Calculating population within each reporting unit. Intermediate: pwzm_populationCnt_0
[YYYY-MM-DD hh:mm:ss] Making a working copy of Census2010. Intermediate: pwzm_Census2010_Work_0
[YYYY-MM-DD hh:mm:ss] Making a working copy of Daycares. Intermediate: pwzm_Daycares_Work_0
[YYYY-MM-DD hh:mm:ss] Dissolving pwzm_Daycares_Work_1. Intermediate: pwzm_Daycares_Dissolve_0
[YYYY-MM-DD hh:mm:ss] Assigning reporting unit IDs to Daycares. Intermediate: pwzm_Daycares_Identity_0
[YYYY-MM-DD hh:mm:ss] Calculating population within zone areas for each reporting unit. Intermediate: pwzm_populationCnt_0
[YYYY-MM-DD hh:mm:ss] Calculating the percent of the population that is within a zone for each reporting unit
Start Time: Day, Month DD, YYYY hh:mm:ss AM/PM
Succeeded at Day, Month DD, YYYY hh:mm:ss AM/PM (Elapsed Time: ##.## units)
[YYYY-MM-DD hh:mm:ss] Calculation complete
Summarizing the ATtILA metric output table to log file
Summary complete
Log file closed

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