Cursor (arcpy)

Resumen

A cursor is a data access object that can be used either to iterate through the set of rows in a table or to insert new rows into a table. Cursors have three forms: search, insert, or update. Cursors are commonly used to read and update attributes.

Descripción general de los métodos

Método	Explicación
deleteRow (row)	Deletes a row in the database. The row corresponding to the current position of the cursor will be deleted.
insertRow (row)	Inserts a new row into the database.
newRow ()	Creates an empty row object.
next ()	Returns the next object at the current index.
reset ()	Sets the current enumeration index (used by the next method) back to the first element.
updateRow (row)	The updateRow method can be used to update the row at the current position of an update cursor.

Métodos

deleteRow (row)

Parámetro	Explicación	Tipo de datos
row	The row to be deleted.	Row

insertRow (row)

Parámetro	Explicación	Tipo de datos
row	The row to be inserted.	Row

newRow ()

Valor de retorno

Tipo de datos	Explicación
Row	A new empty row object.

next ()

Valor de retorno

Tipo de datos	Explicación
Object	The next object at the current index.

reset ()

updateRow (row)

Parámetro	Explicación	Tipo de datos
row	The row used to update the current position of the cursor.	Row

Ejemplo de código

Cursor example 1

Use search cursor to view field values in row.

import arcpy
from arcpy import env

# Set the workspace
#
env.workspace = "D:/St_Johns/data.gdb"

# Create the search cursor
#
cur = arcpy.SearchCursor("roads", '"TYPE" <> 4')

# Iterate through the rows in the cursor
#
for row in cur:
    print "Name: %s,  CFCC code: %s" % (row.NAME, row.CFCC)

del cur, row

Cursor example 2

Use an update cursor to change field values in rows.

import arcpy
from arcpy import env
# Set the workspace
#
env.workspace = "D:/St_Johns/data.gdb"

# Create the update cursor
#
cur = arcpy.UpdateCursor("roads")

# Update the road buffer distance field based on road type.
#   Road type is either 1,2,3,4  Distance is in meters.
for row in cur:
    row.BUFFER_DIST = row.TYPE * 100
    cur.updateRow(row)

# Delete cursor and row objects
#
del cur, row

Cursor example 3

Use an insert cursor to create new rows in table.

import arcpy
import time 

# Create insert cursor for table 
# 
cur = arcpy.InsertCursor("D:/St_Johns/data.gdb/roads_maint") 
x = 1000 

# Create 25 new rows. Set default values on distance and CFCC code 
# 
while x <= 1025: 
    row = cur.newRow() 
    row.rowid = x 
    row.distance = 100
    row.CFCC = "A10" 
    row.LastInsp = time.ctime() 
    cur.insertRow(row) 
    x += 1

# Delete cursor and row objects
#
del cur, row