ArcGIS中的Python。 需要访问字符串元素

Question

ArcGIS 10.0

I used arcpy.UpdateCursor for access to my field:

import arcpy
import sys

layer = sys.argv[1]#my table
field = sys.argv[2]#target field in table

cursor = arcpy.UpdateCursor(layer)

for row in cursor:
    attrString = row.getValue("field")
    subString = attrString[3]
    row.setValue(field,subString)
    cursor.updateRow(row)

My problem is that I want to access the element of string, which has variable "row", but is it not support indexes and not iterable. Can you please recommend other methods ?

Answer 1

The ArcGIS help pages about UpdateCursors and Accessing data using cursors are useful background information.

The UpdateCursor function creates a "cursor" object, which is made up of "row" objects. Each of these rows represents an individual feature of the feature class or layer.

To access data (whether reading or updating) from a row object, you need to specify the field name instead of a numerical index. So, if you're checking whether attribute letter is equal to E :

if row.getValue("letter") == "E":
    # do stuff

Once you have gotten that attribute value stored in another variable, you can access elements of the resulting string and do any Python string manipulation you want:

attrString = row.getValue("street")
subString = attrString[11]
newString = attrString.replace("B", "t")
attrString[11] = "t"

Answer 2

Problem resolve. I replace "field" to field and now works fine.

import arcpy
import sys

layer = sys.argv[1]#my table
field = sys.argv[2]#target field in table

cursor = arcpy.UpdateCursor(layer)

for row in cursor:
    attrString = row.getValue(field)
    subString = attrString[3]
    row.setValue(field,subString)
    cursor.updateRow(row)

Answer 3

Work with the newer version of cursors: arcpy.da.UpdateCursor and you will have the row[field] indexing for which I believe you were originally looking.

You have to be using ArcGIS >= 10.1 for access to da. cursors. ArcGIS 10.3 Help for arcpy.da