摘要
从要素类或表中返回属性值行。
SearchCursor 函数遍历 Row 对象并提取字段值。
说明
旧版本:
自 ArcGIS 10.1 起,此功能已由 arcpy.da.SearchCursor 取代。 为了获得更快性能,请使用 arcpy.da.SearchCursor。
可用于迭代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 expression that limits the rows returned in the cursor. For more information on where clauses and SQL statements, see Write a query in the query builder. | String |
spatial_reference | When specified, features will be projected on the fly using the spatial_reference provided. | SpatialReference |
fields | A semicolon-delimited string of 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 for ascending and D descending, using the form "field1 A;field2 D". | String |
数据类型 | 说明 |
Cursor | 可分发 Row 对象的 Cursor 对象。 |
代码示例
列出 Counties.shp 的字段内容。 游标按州名称和人口进行排序。
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")))