使用添加字段和字段计算器的Python for ArcGIS for循环

Question

I'll try to give a brief background here. I recently received a large amount of data that was all digitized from paper maps. Each map was saved as an individual file that contains a number of records (polygons mostly). My goal is to merge all of these files into one shapefile or geodatabase, which is an easy enough task. However, other than spatial information, the records in the file do not have any distinguishing information so I would like to add a field and populate it with the original file name to track its provenance. For example, in the file "505_dmg.shp" I would like each record to have a "505_dmg" id in a column in the attribute table labeled "map_name". I am trying to automate this using Python and feel like I am very close. Here is the code I'm using:

# Import system module
import arcpy
from arcpy import env
from arcpy.sa import *

# Set overwrite on/off
arcpy.env.overwriteOutput = "TRUE"

# Define workspace
mywspace = "K:/Research/DATA/ADS_data/Historic/R2_ADS_Historical_Maps/Digitized Data/Arapahoe/test"
print mywspace

# Set the workspace for the ListFeatureClass function
arcpy.env.workspace = mywspace

try:
    for shp in arcpy.ListFeatureClasses("","POLYGON",""):
        print shp
        map_name = shp[0:-4]
        print map_name
        arcpy.AddField_management(shp, "map_name", "TEXT","","","20")
        arcpy.CalculateField_management(shp, "map_name","map_name", "PYTHON")
except:
     print "Fubar, It's not working"
     print arcpy.GetMessages()
else:
     print "You're a genius Aaron"

The output I receive from running this script:

>>> 

K:/Research/DATA/ADS_data/Historic/R2_ADS_Historical_Maps/Digitized Data/Arapahoe/test
505_dmg.shp
505_dmg
506_dmg.shp
506_dmg
You're a genius Aaron

Appears successful, right? Well, it has been...almost: a field was added and populated for both files, and it is perfect for 505_dmg.shp file. Problem is, 506_dmg.shp has also been labeled "505_dmg" in the "map_name" column. Though the loop appears to be working partially, the map_name variable does not seem to be updating. Any thoughts or suggestions much appreciated.

Thanks,

Aaron

Answer 1

I received a solution from the ESRI discussion board: https://geonet.esri.com/thread/114520

Basically, a small edit in the Calculate field function did the trick. Here is the new code that worked:

arcpy.CalculateField_management(shp, "map_name","\"" + map_name + "\"", "PYTHON")