Feature Compare (Data Management)
Summary
Compares two feature classes or layers and returns the comparison results. Feature Compare can report differences with geometry, tabular values, spatial reference, and field definitions.
Usage
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The tool returns messages showing the comparison result. By default, the tool will stop executing after encountering the first miscompare. To report all differences, set the continue compare option to true.
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Multiple sort fields may be specified. The first field is sorted, then the second field, and so on, in ascending order. Sorting by a common field in both the Input Base Features and the Input Test Features ensures that you are comparing the same row from each input dataset.
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By default, the compare type is set to ALL. This means all properties of the features being compared will be checked, including such things as spatial reference, field properties, attributes, and geometry. However, you may choose a different compare type to check only specific properties of the features being compared.
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The Ignore Options provides the flexibility to omit properties such as measure attributes, z attributes, point ID attributes, and extension properties. Two feature classes may be identical, yet one has measures and z coordinates and the other does not. You can choose to ignore these properties. The IGNORE_EXTENSION_PROPERTIES option refers to additional information added to a feature class or table. For example, the features of two annotation feature classes can be identical but the feature classes may have different extension properties, such as different symbols in the symbol collection and different editing behavior.
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The default XY Tolerance is determined by the default XY Tolerance of the Input Base Features. To minimize error, the value you choose for the compare tolerance should be as small as possible. If zero is entered for the XY Tolerance, an exact match is performed.
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The default M Tolerance and the default Z Tolerance is determined by the default M Tolerance and Z Tolerance of the Input Base Features. The units are the same as those of the Input Base Features. If zero is entered for the M Tolerance and Z Tolerance, an exact match is performed.
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When comparing GEOMETRY_ONLY, the spatial references must match. If the spatial references are different, a miscompare will be reported. If the coordinate system is different for either input, the features will miscompare. This tool does not do projection on the fly.
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The Omit Fields parameter is a list of fields that are not included in the field count comparison—their field definitions and tabular values are ignored.
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Attribute tolerances can only be specified for numeric field types.
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The Output Compare File will contain all similarities and differences between the Input Base Features and the Input Test Features. This file is a comma-delimited text file which can be viewed and used as a table in ArcGIS. For example, this table can be queried to obtain all the ObjectID values for all the rows that are different. The "has_error" field indicates that the record contains an error. True indicates there is a difference.
One of the first comparisons performed is a feature count. If the feature count is reported as being different and the Continue Compare parameter is True the subsequent comparison messages may not accurately reflect additional differences between the Input Base Features and Input Test Features. This is due to Feature Compare inability to figure out where features have been added or removed in the Input Test Features and simply moves to the next row in each attribute table. At the location in the attribute table where a feature has been added or deleted the tool will simply move to the next row and begin comparing the base feature with the wrong test feature because the correct one in the Input Test Data was deleted or a feature was added before it.
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The comparison tools result object will be 'true' when no differences are found and 'false' when differences are detected.
Syntax
| Parameter | Explanation | Data Type |
in_base_features |
The Input Base Features are compared with the Input Test Features. Input Base features refers to data that you have declared valid. This base data has the correct geometry definitions, field definitions, and spatial reference. | Feature Layer |
in_test_features |
The Input Test Features are compared against the Input Base Features. Input Test Features refers to data that you have made changes to by editing or compiling new features. | Feature Layer |
sort_field [sort_field,...] |
The field or fields used to sort records in the Input Base Table and the Input Test Table. The records are sorted in ascending order. Sorting by a common field in both the Input Base Features and the Input Test Features ensures that you are comparing the same row from each input dataset. | Value Table |
compare_type (Optional) |
The comparision type. ALL is the default. The default will compare all properties of the features being compared.
| String |
ignore_options [ignore_option,...] (Optional) |
These properties will not be compared during comparison.
| String |
xy_tolerance (Optional) |
The distance that determines the range in which features are considered equal. To minimize error, the value you choose for the compare tolerance should be as small as possible. By default, the compare tolerance is the XY Tolerance of the input base features. | Linear unit |
m_tolerance (Optional) |
The measure tolerance is the minimum distance between measures before they are considered equal. | Double |
z_tolerance (Optional) |
The Z Tolerance is the minimum distance between Z coordinates before they are considered equal. | Double |
attribute_tolerances [[Field, {Tolerance}],...] (Optional) |
The numeric value that determines the range in which attribute values are considered equal. This only applies to numeric field types. | Value Table |
omit_field [omit_field,...] (Optional) |
The field or fields that will be omitted during comparison. The field definitions and the tabular values for these fields will be ignored. | String |
continue_compare (Optional) |
Indicates whether to compare all properties after encountering the first mismatch.
| Boolean |
out_compare_file (Optional) |
This file will contain all similarities and differences between the Input Base Features and the Input Test Features. This file is a comma-delimited text file that can be viewed and used as a table in ArcGIS. | File |
Code Sample
The following Python window script demonstrates how to use the FeatureCompare function in immediate mode.
import arcpy
arcpy.FeatureCompare_management(r'C:/Workspace/baseroads.shp', r'C:/Workspace/newroads.shp', 'ROAD_ID', 'ALL', 'IGNORE_M;IGNORE_Z', '0.001 METERS', 0, 0, 'Shape_Length 0.001', '#', 'CONTINUE_COMPARE', e = r'C:/Workspace/roadcompare.txt')
Example of how to use the FeatureCompare tool in a stand-alone script.
# Name: FeatureCompare.py
# Description: Compare two feature classes and return comparison result.
# import system modules
import arcpy
try:
# Set local variables
base_features = "C:/Workspace/baseroads.shp"
test_features = "C:/Workspace/newroads.shp"
sort_field = "ROAD_ID"
compare_type = "ALL"
ignore_option = "IGNORE_M;IGNORE_Z"
xy_tolerance = "0.001 METERS"
m_tolerance = 0
z_tolerance = 0
attribute_tolerance = "Shape_Length 0.001"
omit_field = "#"
continue_compare = "CONTINUE_COMPARE"
compare_file = "C:/Workspace/roadcompare.txt"
# Process: FeatureCompare
compare_result = arcpy.FeatureCompare_management(base_features, test_features, sort_field, compare_type, ignore_option, xy_tolerance, m_tolerance, z_tolerance, attribute_tolerance, omit_field, continue_compare, compare_file)
print compare_result
print arcpy.GetMessages()
except:
# Print error message if an error occurs
print arcpy.GetMessages()