摘要
从要素类或表中更新或删除属性值行。
该游标将数据锁定保留至脚本完成或更新游标对象被删除时。
旧版本:
此函数在 ArcGIS 10.1 中已被 arcpy.da.UpdateCursor 取代,保留此函数仅供旧版脚本使用。 要改进性能、功能和支持更新的字段类型和令牌,请使用 arcpy.da.UpdateCursor。
说明
可用于迭代更新游标的方式有两种:for 循环或者 while 循环(通过游标的 next 方法返回下一行)。 如果要使用游标的 next 方法来检索行数为 N 的表中的所有行,则脚本必须调用 next N 次。 在检索到结果集中的最后一行后调用 next 将返回一个 None 类型,在此处用作占位符。
在 for 循环中遍历 UpdateCursor 函数返回的行。
import arcpy
fc = "c:/data/base.gdb/roads"
field1 = "field1"
field2 = "field2"
cursor = arcpy.UpdateCursor(fc)
for row in cursor:
# field2 will be equal to field1 multiplied by 3.0
row.setValue(field2, row.getValue(field1) * 3.0)
cursor.updateRow(row)
在 while 循环中遍历 UpdateCursor 函数返回的行。
import arcpy
fc = "c:/data/base.gdb/roads"
field1 = "field1"
field2 = "field2"
cursor = arcpy.UpdateCursor(fc)
row = cursor.next()
while row:
# field2 will be equal to field1 multiplied by 3.0
row.setValue(field2, row.getValue(field1) * 3.0)
cursor.updateRow(row)
row = cursor.next()
语法
UpdateCursor (dataset, {where_clause}, {spatial_reference}, {fields}, {sort_fields})
参数 | 说明 | 数据类型 |
dataset | The feature class or table containing the rows to be updated or deleted. | String |
where_clause | An expression that limits the rows returned in the cursor. For more information about where clauses and SQL statements, see Introduction to query expressions. | String |
spatial_reference | Coordinates are specified in the spatial_reference value provided and converted on the fly to the coordinate system of the dataset. | SpatialReference |
fields | A semicolon-delimited string of fields to be included in the cursor. By default, all fields are included. | String |
sort_fields | The fields used to sort the rows in the cursor. Ascending and descending order for each field is denoted by A for ascending and D for descending, using the form "field1 A;field2 B". | String |
数据类型 | 说明 |
Cursor | 返回 Row 对象的 Cursor 对象。 |
代码示例
根据另一个字段值更新要素类中的字段值。
import arcpy
# Create an update cursor for a feature class
rows = arcpy.UpdateCursor("c:/data/base.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.setValue("BUFFER_DISTANCE", row.getValue("ROAD_TYPE") * 100)
rows.updateRow(row)
# Delete cursor and row objects to remove locks on the data.
del row
del rows