Zonal Geometry as Table (Spatial Analyst)
Summary
Calculates for each zone in a dataset the geometry measures (area, perimeter, thickness, and the characteristics of ellipse) and reports the results as a table.
Illustration
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ZonalGeometryAsTable(InRas1,"VALUE",Out_Geom,1) |
VALUE AREA PERIMETER THICKNESS XCENTROID YCENTROID MAJORAXIS MINORAXIS ORIENTATION 0 5.0 14.0 0.5 2.300 2.100 2.338 0.681 60.714 1 5.0 14.0 0.5 1.900 2.100 2.668 0.596 126.061 2 3.0 8.0 0.5 3.167 2.167 1.286 0.743 135.000 4 2.0 6.0 0.5 0.500 1.000 1.128 0.564 90.000
Usage
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A zone is defined as all areas in the input that have the same value. The areas do not have to be contiguous. Both raster and feature datasets can be used for the zone input.
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If the input zone data is a feature dataset, a cell size must be set either by the Processing cell size or in the Cell Size environment.
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The calculations for each zone are recorded in the output table.
When specifying the input zone data, the default zone field will be the first available valid field. If no other valid fields exist, the ObjectID field (for example, OID or FID) will be the default.
If a reserved field (for example, OBECTID, FID, or OID) is selected for the Zone field, then this may cause some ambiguity in the result. The result includes the particular reserved field name necessary for the particular output format type, as well as the Zone field specified. If the specified field has the same name as the reserved field for the particular output format, in the output the name for the zone field will be altered in such a way that all field names in the result are unique.
Note:To make a field of unique values that does not have a reserved name, use the Add Field and Calculate Field geoprocessing tools.
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In the output table, the value field always precedes the fields containing the zonal output calculations. The value field contains the values of the zones defined by the zone dataset.
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The values for the zonal calculations will be floating point.
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Other than the ORIENTATION item, all the results in the output table are presented in map units. The ORIENTATION item values are in degrees, with a possible range of 0 to 180. The ORIENTATION is defined as an angle between the x-axis and the major axis of the ellipse. The values of the orientation angle increase counterclockwise, starting at 0 in the east (horizontal, to the right) and going through 90 when the major axis is vertical.
If a particular zone consists of only one cell or if the zone is a single square block of cells, the orientation of the ellipse (which, in this case, is a circle) is set to 90 degrees.
Syntax
| Parameter | Explanation | Data Type |
in_zone_data |
Dataset that defines the zones. The zones can be defined by an integer raster or a feature layer. | Raster Layer | Feature Layer |
zone_field | Field that holds the values that define each zone. It must be an integer field of the zone dataset. | Field |
out_table |
Output table that will contain the summary of the values in each zone. | Table |
processing_cell_size (Optional) | The processing cell size for the zonal operation. This is the value in the environment if specifically set. If the environment is not set, the default for the cell size is determined by the type of the zone data as follows:
| Analysis Cell Size |
Code Sample
This example determines the geometry measures for each zone defined by the input polygon shape file.
import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outZonalGeometryAsTable = ZonalGeometryAsTable("zones.shp", "Classes", "zonalgeomout", 0.2)
This example determines the geometry measures for each zone defined by the input polygon shape file.
# Name: ZonalGeometryAsTable_Ex_02.py
# Description:Calculates for each zone in a dataset the specified geometry
# measure (area, perimeter, thickness, or the characteristics
# of ellipse) and reports the results as a table.
# Requirements: Spatial Analyst Extension
# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *
# Set environment settings
env.workspace = "C:/sapyexamples/data"
# Set local variables
inZoneData = "zones.shp"
zoneField = "Classes"
outTable = "zonalgeomout02.dbf"
processingCellSize = 0.2
# Check out the ArcGIS Spatial Analyst extension license
arcpy.CheckOutExtension("Spatial")
# Execute ZonalGeometryAsTable
outZonalGeometryAsTable = ZonalGeometryAsTable(inZoneData, zoneField, "AREA", cellSize)