Desktop Help 10.0

摘要

The FieldMap object provides a field definition and a list of input fields taken from a set of tables or feature classes.

讨论

FieldMappings 对象是一组 FieldMap 对象，它用作执行字段映射的工具的参数值，如 Merge。要处理这些对象，最简单的方法就是先创建 FieldMappings 对象，然后通过添加要组合的输入要素类或表对 FieldMap 对象进行初始化。提供了所有输入后，FieldMappings 对象将为所有输入中的每个唯一字段名提供一个 FieldMap 对象或输出字段。可对此列表进行修改，具体方法有添加新字段、更改输出字段的属性和/或内容，或移除任何不需要的输出字段。

FieldMap 对象的属性包括输入文本值的起始位置和结束位置，因此可以使用一组输入值创建新的输出值。如果 FieldMap 对象包含多个来自同一表或要素类的输入字段，则将使用 mergeRule 属性合并每个记录的值。这样可以方便地连接各个值，例如保存在一个字段中的街道名称以及保存在另一个字段中的街道类型，如 Eureka 和 Street。如果将 mergeRule 的值指定为 Join，则使用 FieldMap 的 joinDelimiter 属性。任何字符集（如空格）都可用作分隔符。在以上示例中，将会创建值 Eureka Street。

语法

FieldMap ()

属性

属性	说明	数据类型
inputFieldCount （只读）	Get the count of subfields.	Integer
joinDelimiter （可读写）	Join delimiter for the subfields.	String
mergeRule （可读写）	Merge rule for the subfields.	String
outputField （可读写）	Get the properties field.	Field

方法概述

方法	说明
addInputField (table_dataset, field_name, {start_position}, {end_position})	Adds input field to the field map.
findInputFieldIndex (table_dataset, field_name)	Finds an input field from the field map.
getEndTextPosition (index)	Gets end text position from the field map.
getInputFieldName (index)	Gets the name of an input field from the field map, based on the field's index.
getInputTableName (index)	Gets the name of an input table from the field map, based on the table's index.
getStartTextPosition (index)	Gets start text position from the field map.
removeAll ()	Removes all values and creates an empty object.
removeInputField (index)	Removes an input field from the field map.
setEndTextPosition (index, end_position)	Sets end text position for the field map.
setStartTextPosition (index, start_position)	Sets the start text position from the field map.

方法

addInputField (table_dataset, field_name, {start_position}, {end_position})

参数	说明	数据类型
table_dataset	The table added to the field map.	String
field_name	The input field name.	String
start_position	The start position of an input text value. (默认值为 -1)	Integer
end_position	The end position of an input text value. (默认值为 -1)	Integer

findInputFieldIndex (table_dataset, field_name)

参数	说明	数据类型
table_dataset	The table added to the field map.	String
field_name	The field name.	String

返回值

数据类型	说明
Integer	The index position of the field name.

getEndTextPosition (index)

参数	说明	数据类型
index	The index position.	Integer

返回值

数据类型	说明
Integer	The end text position.

getInputFieldName (index)

参数	说明	数据类型
index	The index position.	Integer

返回值

数据类型	说明
String	The input field name.

getInputTableName (index)

参数	说明	数据类型
index	The index position.	Integer

返回值

数据类型	说明
String	The input table name.

getStartTextPosition (index)

参数	说明	数据类型
index	The index position.	Integer

返回值

数据类型	说明
Integer	The start text position.

removeAll ()

removeInputField (index)

参数	说明	数据类型
index	The index position.	Integer

setEndTextPosition (index, end_position)

参数	说明	数据类型
index	The index position.	Integer
end_position	The end position of an input text value.	Integer

setStartTextPosition (index, start_position)

参数	说明	数据类型
index	The index position.	Integer
start_position	The start position of an input text value.	Integer

代码示例

FieldMap example

import arcpy
from arcpy import env

# Input feature classes contain a PID field that is a composite of
#   the Township, Range, Section, QuarterSection, Block, Lot, and SubLot values.
#   We need to define how to break the PID field into two fields: TWNSHIP and BLOCK,
#   then run the Merge tool.
#   PID field and field map. 
#                    1 1 1 1 1 1 1
#  1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
# +-------------------------------+
# |2|0|3|0|8|2|1|0|0|1|0|0|5|0|0|0|
# +-------------------------------+
# +---TWNSHIP---+-------BLOCK-----+

infc1 = "C:/Data/NewParcels.shp"
infc2 = "Parcels"
outfc = "Parcels_Merge"

# Create a fieldmappings object and two fieldmap objects
#
fieldmappings = arcpy.FieldMappings()
fldmap_TWNSHIP = arcpy.FieldMap()
fldmap_BLOCK = arcpy.FieldMap()

# Create a value table to hold names of input feature classes for Merge tool.
#
vt = arcpy.ValueTable()

# Add all fields from first input feature class to fieldmappings object
#   AddTable is the most efficient way.
#
fieldmappings.addTable(infc1)

# Add the TWNSHIP and BLOCK field from the first input feature class 
#   to fieldmap object.
#
fldmap_TWNSHIP.addInputField(infc1)
fldmap_BLOCK.addInputField(infc1)
vt.addRow(infc1)

# Add all fields from second input feature class to fieldmappings object
#
env.workspace = "C:/Data/Boulder.gdb"
fieldmappings.addTable(infc2)

# Add the TWNSHIP and BLOCK field from the second input feature class 
#   to fieldmap object.
#
fldmap_TWNSHIP.addInputField(infc2)
fldmap_BLOCK.addInputField(infc2)
vt.addRow(infc2)

# Set the starting and ending positions of the input field in the fieldmap.
#   This is for TWNSHIP
for x in range(0, fldmap_TWNSHIP.inputFieldCount):
    fldmap_TWNSHIP.setStartTextPosition(x, 0)
    fldmap_TWNSHIP.setEndFieldPosition(x, 6)

# Set the starting and ending positions of the input field in the fieldmap.
#   This is for BLOCK
for x in range(0, fldmap_BLOCK.inputFieldCount):
    fldmap_BLOCK.setStartTextPosition(x, 7)
    fldmap_BLOCK.setEndFieldPosition(x, 15)

# Get the new field object from fieldmap, set field name, place back in fieldmap.
#
fld_TWNSHIP = fldmap_TWNSHIP.outputField
fld_TWNSHIP.name = "TWNSHIP"
fldmap_TWNSHIP.outputField = fld_TWNSHIP
fld_BLOCK = fldmap_BLOCK.outputField
fld_BLOCK.name = "BLOCK"
fldmap_BLOCK.outputField = fld_BLOCK

# Add the new fieldmap object to fieldmappings object.
fieldmappings.addFieldMap(fldmap_TWNSHIP)
fieldmappings.addFieldMap(fldmap_BLOCK)

#Run the Merge tool
arcpy.Merge_management(vt, outfc, fieldmappings)

FieldMap

摘要

讨论

语法

属性

方法概述

方法

代码示例

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