SearchCursor

Summary

SearchCursor establishes read-only access to the records returned from a feature class or table.

It returns an iterator of tuples. The order of values in the tuple matches the order of fields specified by the field_names argument.

Discussion

Geometry properties can be accessed by specifying the token SHAPE@ in the list of fields.

Search cursors can be iterated using a for loop. Search cursors also support with statements to reset iteration and aid in removal of locks. However, using a del statement to delete the object or wrapping the cursor in a function to have the cursor object go out of scope should be considered to guard against all locking cases.

The records returned by SearchCursor can be constrained to match attribute criteria or spatial criteria.

Accessing full geometry with SHAPE@ is an expensive operation. If only simple geometry information is required, such as the x,y coordinates of a point, use tokens such as SHAPE@XY, SHAPE@Z, and SHAPE@M for faster, more efficient access.

In Python 2, SearchCursor supports the iterator next method to retrieve the next row outside of a loop. In Python 3, the equivalent is performed using the Python built-in next function.

Syntax

SearchCursor (in_table, field_names, {where_clause}, {spatial_reference}, {explode_to_points}, {sql_clause}, {datum_transformation})

Parameter	Explanation	Data Type
in_table	The feature class, layer, table, or table view.	String
field_names [field_names,...]	A list (or tuple) of field names. For a single field, you can use a string instead of a list of strings. Use an asterisk (*) instead of a list of fields to access all fields from the input table (BLOB fields are excluded). However, for faster performance and reliable field order, it is recommended that the list of fields be narrowed to only those that are actually needed. Additional information can be accessed using tokens (such as OID@) in place of field names: SHAPE@XY—A tuple of the feature's centroid x,y coordinates. SHAPE@XYZ—A tuple of the feature's centroid x,y,z coordinates. SHAPE@TRUECENTROID—A tuple of the feature's centroid x,y coordinates. This returns the same value as SHAPE@XY. SHAPE@X—A double of the feature's x-coordinate. SHAPE@Y—A double of the feature's y-coordinate. SHAPE@Z—A double of the feature's z-coordinate. SHAPE@M—A double of the feature's m-value. SHAPE@JSON— The Esri JSON string representing the geometry. SHAPE@WKB—The well-known binary (WKB) representation for OGC geometry. It provides a portable representation of a geometry value as a contiguous stream of bytes. Values are returned as a bytearray object. SHAPE@WKT—The well-known text (WKT) representation for OGC geometry. It provides a portable representation of a geometry value as a text string. SHAPE@—A geometry object for the feature. SHAPE@AREA—A double of the feature's area. SHAPE@LENGTH—A double of the feature's length. OID@—The value of the Object ID field.	String
where_clause	An optional expression that limits the records returned. For more information on where clauses and SQL statements, see SQL reference for query expressions used in ArcGIS. (The default value is None)	String
spatial_reference	The spatial reference of the feature class. When this argument is specified, the feature will be projected (or transformed) from the input's spatial reference. If unspecified, the input feature classes' spatial reference will be used. Valid values for this argument are a SpatialReference object or string equivalent. If a spatial reference is specified, but the input feature class has an unknown spatial reference, neither a projection nor transformation can be completed. The geometry returned by the cursor will have coordinates matching the input, with a spatial reference updated to the one specified. (The default value is None)	SpatialReference
explode_to_points	Deconstruct a feature into its individual points or vertices. If explode_to_points is set to True, a multipoint feature with five points, for example, is represented by five rows. (The default value is False)	Boolean
sql_clause	A pair of SQL prefix and postfix clauses organized in a list or tuple. An SQL prefix clause supports None, DISTINCT, and TOP. An SQL postfix clause supports None, ORDER BY, and GROUP BY. Use DISTINCT in a prefix clause. with arcpy.da.SearchCursor( in_features, ["OID@", "STREET_NAME"], sql_clause=("DISTINCT STREET_NAME", None) ) as cur: Use TOP in a prefix clause, and ORDER BY in a postfix clause. with arcpy.da.SearchCursor( in_features, ['OID@', "ELEVATION"], sql_clause=("TOP 5", "ORDER BY ELEVATION DESC") ) as cur: Use GROUP BY in a postfix clause. with arcpy.da.SearchCursor( in_features, ['STREET_NAME'], sql_clause=(None, "GROUP BY STREET_NAME") ) as cur: An SQL prefix clause is positioned in the first position and will be inserted between the SELECT keyword and the SELECT COLUMN LIST. The SQL prefix clause is most commonly used for clauses such as DISTINCT or ALL. An SQL postfix clause is positioned in the second position and will be appended to the SELECT statement, following the where clause. The SQL postfix clause is most commonly used for clauses such as ORDER BY. Note: DISTINCT, ORDER BY, and ALL are only supported when working with databases. They are not supported by other data sources (such as dBASE or INFO tables). TOP is only supported by SQL Server databases. (The default value is (None, None))	tuple
datum_transformation	When the cursor projects the features from one spatial reference to another, if the spatial references do not share the same datum, an appropriate datum transformation should be specified. The ListTransformations function can be used to provide a list of valid datum transformations between two spatial references. Learn more about datum transformations (The default value is None)	String

Properties

Property	Explanation	Data Type
fields (Read Only)	A tuple of field names used by the cursor. The tuple will include all fields and tokens specified by the field_names argument. The order of the field names on the fields property will be the same as passed in with the field_names argument. If the field_names argument is set to *, the fields property will include all fields used by the cursor. A value of * will return geometry in a tuple of x,y coordinates (equivalent to the SHAPE@XY token).	tuple

Method Overview

Method	Explanation
reset ()	Resets the cursor back to the first row.

Methods

reset ()

Code sample

SearchCursor example 1

Use SearchCursor to step through a feature class and print specific field values and the x,y coordinates of the point.

import arcpy

fc = 'c:/data/base.gdb/well'
fields = ['WELL_ID', 'WELL_TYPE', 'SHAPE@XY']

# For each row, print the WELL_ID and WELL_TYPE fields, and
# the feature's x,y coordinates
with arcpy.da.SearchCursor(fc, fields) as cursor:
    for row in cursor:
        print(u'{0}, {1}, {2}'.format(row[0], row[1], row[2]))

SearchCursor example 2

Use SearchCursor to return a set of unique field values.

import arcpy

fc = 'c:/data/base.gdb/well'
field = 'Diameter'

# Use SearchCursor with list comprehension to return a
# unique set of values in the specified field
values = [row[0] for row in arcpy.da.SearchCursor(fc, field)]
uniqueValues = set(values)

print(uniqueValues)

SearchCursor example 3

Use SearchCursor to return attributes using tokens.

import arcpy

fc = 'c:/data/base.gdb/well'

# For each row, print the Object ID field, and use the SHAPE@AREA
#  token to access geometry properties
with arcpy.da.SearchCursor(fc, ['OID@', 'SHAPE@AREA']) as cursor:
    for row in cursor:
        print('Feature {} has an area of {}'.format(row[0], row[1]))

SearchCursor example 4

Use SearchCursor with a where clause to identify features that meet specific criteria.

import arcpy

fc = 'c:/base/data.gdb/roads'
class_field = 'Road Class'
name_field = 'Name'

# Create an expression with proper delimiters
expression = u'{} = 2'.format(arcpy.AddFieldDelimiters(fc, name_field))

# Create a search cursor using an SQL expression
with arcpy.da.SearchCursor(fc, [class_field, name_field],
                           where_clause=expression) as cursor:
    for row in cursor:
        # Print the name of the residential road
        print(row[1])

SearchCursor example 5A

Use SearchCursor and the Python sorted method to sort rows.

For additional sorting options, see the Python Sorting Mini-HOW TO.

import arcpy

fc = 'c:/data/base.gdb/well'
fields = ['WELL_ID', 'WELL_TYPE']

# Use Python's sorted method to sort rows
for row in sorted(arcpy.da.SearchCursor(fc, fields)):
    print(u'{0}, {1}'.format(row[0], row[1]))

SearchCursor example 5B

Alternatively, sort using sql_clause if the data supports SQL ORDER BY.

Note:

ORDER BY is only supported when working with databases. It is not supported by other data sources (such as dBASE or INFO tables).

import arcpy

fc = 'c:/data/base.gdb/well'
fields = ['WELL_ID', 'WELL_TYPE']

# Use ORDER BY sql clause to sort field values
for row in arcpy.da.SearchCursor(
        fc, fields, sql_clause=(None, 'ORDER BY WELL_ID, WELL_TYPE')):
    print(u'{0}, {1}'.format(row[0], row[1]))

SearchCursor example 6

Use SQL TOP to limit the number of records to return.

Note:

TOP is only supported by SQL Server and MS Access databases.

import arcpy

fc = 'c:/data/base.mdb/well'
fields = ['WELL_ID', 'WELL_TYPE']

# Use SQL TOP to sort field values
for row in arcpy.da.SearchCursor(fc, fields, sql_clause=('TOP 3', None)):
    print(u'{0}, {1}'.format(row[0], row[1]))