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SearchCursor

摘要

SearchCursor 函数用于在要素类或表上建立只读游标。SearchCursor 可用于遍历行对象并提取字段值。可以使用 where 子句或字段限制搜索，并对结果排序。

说明

以迭代方式搜索游标的方式有两种：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。在检索完结果集的最后一行后调用 next 将返回 None，它是一种 Python 数据类型，此处用作占位符。

通过 for 循环使用 SearchCursor。

import arcpy

fc = "c:/data/base.gdb/roads"
field = "StreetName"
cursor = arcpy.SearchCursor(fc)
for row in cursor:
    print(row.getValue(field))

通过 while 循环使用 SearchCursor。

import arcpy

fc = "c:/data/base.gdb/roads"
field = "StreetName"
cursor = arcpy.SearchCursor(fc)
row = cursor.next()
while row:
    print(row.getValue(field))
    row = cursor.next()

语法

SearchCursor (dataset, {where_clause}, {spatial_reference}, {fields}, {sort_fields})
参数说明数据类型
dataset

The feature class, shapefile, or table containing the rows to be searched.

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

When specified, features will be projected on the fly using the spatial_reference provided.

SpatialReference
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

返回值

数据类型说明
Cursor

Cursor 对象可分发行对象。

代码示例

SearchCursor 示例

列出 Counties.shp 的字段内容。游标按“州名称”和“人口”排序。

import arcpy

# Open a searchcursor
#  Input: C:/Data/Counties.shp
#  Fields: NAME; STATE_NAME; POP2000
#  Sort fields: STATE_NAME A; POP2000 D
rows = arcpy.SearchCursor("c:/data/counties.shp",
                          fields="NAME; STATE_NAME; POP2000",
                          sort_fields="STATE_NAME A; POP2000 D")

# Iterate through the rows in the cursor and print out the
# state name, county and population of each.
for row in rows:
    print("State: {0}, County: {1}, Population: {2}".format(
        row.getValue("STATE_NAME"),
        row.getValue("NAME"),
        row.getValue("POP2000")))

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