UpdateCursor

Summary

The UpdateCursor function creates a cursor that lets you update or delete rows on the specified feature class, shapefile, or table. The cursor places a lock on the data that will remain until either the script completes or the update cursor object is deleted.

Syntax

UpdateCursor (dataset, {where_clause}, {spatial_reference}, {fields}, {sort_fields})

Parameter	Explanation	Data Type
dataset	The feature class, shapefile, or table containing the rows to be updated or deleted.	String
where_clause	An optional expression that limits the rows returned in the cursor. For more information on WHERE clauses and SQL statements, see About_building_an_SQL_expression.	String
spatial_reference	Coordinates are specified in the spatial_reference provided, and converted on the fly to the coordinate system of the dataset.	Object
fields [fields,...]	The fields to be included in the cursor. By default, all fields are included.	String
sort_fields	Fields used to sort the rows in the cursor. Ascending and descending order for each field is denoted by A and D.	String

Return Value

Data Type	Explanation
Object	A Cursor object that can hand out row objects.

Code Sample

UpdateCursor example

Update field values in feature class, based on another field's value.

import arcpy

# Create update cursor for feature class 
# 
rows = arcpy.UpdateCursor("D:/St_Johns/data.gdb/roads") 

# Update the field used in buffer so the distance is based on the road 
# type. Road type is either 1, 2, 3 or 4. Distance is in meters. 
# 
for row in rows:
    # Fields from the table can be dynamically accessed from the row object.
    #   Here fields named BUFFER_DISTANCE and ROAD_TYPE are used
    row.BUFFER_DISTANCE = row.ROAD_TYPE * 100
    rows.updateRow(row) 

# Delete cursor and row objects to remove locks on the data 
# 
del row 
del rows