Python for ArcGIS：将文本字段添加到形状文件，然后搜索一个字段，如果满足条件，则更新另一个字段

问题描述

我正在独自学习适用于ArcGIS（10.8）的Python（2.7）。我有这个问题：

编写一个脚本，该脚本将文本字段添加到名为roads.shp的要素类中 FERRY并根据需要填充YES和NO值，具体取决于 FEATURE字段的值。

试图弄清楚并检查互联网后，我得到了这个脚本：

from arcpy
from arcpy import env
env.workspace = "C/esriPress/Python/Data/Exercise07/Results" # Set workspace
env.overwriteOutput = True   # overwriting outputs
fc = "roads.shp" # input feature class

newfield = "FERRY"  # new field to be created
fieldtype = "TEXT"  # type of the field that is going to be created
fieldname = arcpy.ValidateFieldName(newfield)  # to determine whether a specific name is valid or not
field_length = 3 # Lenght of th new field to be created
fieldlist = ListFields(fc)  # list the fields in 'fc',it returns a reference number of each object,not the object name.
fieldnames = [] # Create an empty list


# Check whether 'newfield' already exist or not; if not,create it
for field in fieldlist: # For each element in 'fieldlist'...
    fieldnames.append(field.name) #...add in the empty list 'fieldnames' the field name
if fieldname not in fieldnames: # if 'fieldname' don't exists in 'fiednames'...
    arcpy.AddField_management(fc,fieldname,fieldtype,field_length)  # ...Create 'fieldname' in 'fc' with length = 3
    print ("New field has been added")
else:
    print ("Field name already exists.")

​
# Search in the one field and update other field
fields = ['FEATURE',newfield]  # Create a list that contains the field we apply condition,and  the field we going to update
with arcpy.da.UpdateCursor(fc,fields) as cursor: # Setting the cursor; notice the cursor is made up of two fields
    for row in cursor: # For each row in cursor...
        if row[0] == "Ferry Crossing": #...if row in field 1 = "Ferry Crossing'...
            row[1] = "YES" #... Set that row in field 2 to 'Yes'
        else: # Otherwise...
            row[1] = "NO" # ....Set that row in field 2 to 'No'...
        cursor.updateRow(row) # Update cursor
print ("New field has been added" % newfield)

        else:
            row[1] = "NO"
        cursor.updateRow(row)
print ("Field name already exists" % newfield)

但是，当我在PythonWin 2.7.16中运行脚本时，出现以下错误消息：

Failed to run script - syntax error - invalid syntax

我的脚本有什么问题？这是正确的方法吗？

解决方法

似乎您有2个else块和一个额外的cursor.updateRow(row)。 结果，您的print语句未正确缩进。尝试运行以下Update Cursor：

import arcpy

fc = '/path/to/your/geodatabase.gdb/feature_class'

# Add field
arcpy.AddField(fc,"FERRY",field_type = "TEXT")

# Update attributes based on a condition
# Note row[0] is "FEATURE" and row[1] is "FERRY"
with arcpy.da.UpdateCursor(fc,["FEATURE","FERRY"]) as cursor:
    for row in cursor:
        if row[0] == "ADD YOUR CONDITION HERE":
            row[1] = "YES"
        else:
            row[1] = "NO"
        cursor.updateRow(row)