Arcpy add and calculate fields for features in a list

Question

I have a script I am working on and am hitting a runtime error. I am attempting to create a list of all of the shapefiles within a root directory, then add a field to each shapefile and calculate it with the shapefile name. I am able to generate the list (converted from a dictionary) but when I attempt to add the field I encounter the error.

def main():
    try:
        import arcpy, sys, traceback, os, glob
        arcpy.env.overwriteOutput = True
        masterFolder = r"Q:\\GIS\\Field_Data\\MT"
        outputFolder = r"C:\tmp\Shp_merged"

        #collect a list of subfolders in master folder
        subfolderLst = os.listdir(masterFolder)

        #declare a dictionary where a key will be shapefile name
        #... and value a list of pathes to shapefile with this name in all subfolders
        shpDict = {}

        #loop through all subfolders
        for subfolder in subfolderLst:
            #check current subfolder and make a list of pathes to each .shp file
            shpLst = glob.glob(os.path.join(masterFolder,subfolder,'*.shp'))

            #add each shapefile path to dictionary
            for shpPath in shpLst:
                shpName = os.path.basename(shpPath)

                if not shpName in shpDict:
                    shpDict[shpName] = []
                    shpDict[shpName].append(shpPath)

                else:
                    shpDict[shpName].append(shpPath)

        shpDict = shpDict.values()

        print shpDict
        for fc in shpDict:
          arcpy.AddField_management(fc, 'shpname','text')
          arcpy.CalculateField_management(fc, 'shpname', '"'+fc+'"'+ time.strftime('%m_%d_%y'))
    #arcpy.Merge_management(fcs, 'out.shp')


    except:
        print arcpy.GetMessages()
        # Get the traceback object  '"' + wildcard + '"'
        tb = sys.exc_info()[2]
        tbinfo = traceback.format_tb(tb)[0]

        # Concatenate information together concerning the error into a
        #   message string
        pymsg = tbinfo + "\n" + str(sys.exc_type)+ ": " + str(sys.exc_value)

        # Return python error messages for use with a script tool
        arcpy.AddError(pymsg)

        # Print Python error messages for use in Python/PythonWin
        print pymsg

if __name__ == '__main__':
    main()

The list generated looks like this:

[['Q:\\\\GIS\\\\Field_Data\\\\MT\\023N052E\\Points.shp', 'Q:\\\\GIS\\\\Field_Data\\\\MT\\023N053E\\Points.shp', 'Q:\\\\GIS\\\\Field_Data\\\\MT\\024N052E\\Points.shp']]]

and the error:

File "P:\Scripts\scratch\scratch.py", line 45, in main
    arcpy.AddField_management(fc, 'shpname','text')

<type 'exceptions.RuntimeError'>: Object: Error in executing tool

I think it has to do with cursors but being a novice I have no idea how to resolve the problem

Thanks

Answer 1

It looks like one error may be from improper formatting--try replacing:

masterFolder = r"Q:\\GIS\\Field_Data\\MT"

with one of three proper ways of formatting a pathname:

masterFolder = r"Q:\GIS\Field_Data\MT"

or:

masterFolder = "Q:\\GIS\\Field_Data\\MT"

or:

masterFolder = "Q:/GIS/Field_Data/MT"

Answer 2

I strongly suspect that the issue is with using a dictionary inside of the for loop.

If I am reading your code correctly you want 'shpname' to refer to an item in the shpDict list. When you pass these as arguments into the AddField_management function as it is written the computer is interpreting them as strings (literally passing 'shpname' and 'text' as arguments), which don't make sense to ArcGIS and it throws an error.

It might work better to use an iterating value in your loop (I generally use while loops for this kind of thing) and then reference the index of the list as a string in the function. Such as:

while x < len(shpDict):
     arcpy.AddField_management(fc,str(shpDict(x),"TEXT")
     x += 1

Like I said, that's just how I tend to do things like this, there may be a better way. I have had success with this technique - make sure you cast the second argument as a string using the str() function.

I hope that helps you out! If anyone has a more efficient way of accomplishing this, I'd love to hear about it!

Answer 3

Personally, I would do the AddField and CalculateField on each featureclass as I iterated through them. I'd also use the ListFeatureClasses function of arcpy:

def main():
    try:
        import arcpy, sys, traceback, os, glob
        arcpy.env.overwriteOutput = True
        masterFolder = r"Q:\GIS\Field_Data\MT"
        outputFolder = r"C:\tmp\Shp_merged"

        #collect a list of subfolders in master folder
        arcpy.env.workspace = masterFolder
        arcpy.Listworkspaces('','Folder')

        for subfolder in subfolderLst:
            arcpy.env.workspace = subfolder
            fcLst = arcpy.ListFeatureClasses()
            for fc in fcLst:
                arcpy.AddField_management(fc, 'shpname','text')
                arcpy.CalculateField_management(fc, 'shpname', '"'+fc+'"'+ time.strftime('%m_%d_%y'))

    except:
        print arcpy.GetMessages()
        # Get the traceback object  '"' + wildcard + '"'
        tb = sys.exc_info()[2]
        tbinfo = traceback.format_tb(tb)[0]

        # Concatenate information together concerning the error into a
        #   message string
        pymsg = tbinfo + "\n" + str(sys.exc_type)+ ": " + str(sys.exc_value)

        # Return python error messages for use with a script tool
        arcpy.AddError(pymsg)

        # Print Python error messages for use in Python/PythonWin
        print pymsg

if __name__ == '__main__':
    main()

Answer 4

Here is the final code. Thanks to everybod for the help!

import  arcpy

from arcpy import env import os import time def main(): try: import arcpy, sys, traceback, os, glob, shutil arcpy.env.overwriteOutput = True log = r'Q:\1-EMPLOYEE INBOX\David\downloads\logSurveyData.txt' masterFolder = r"Q:\GIS\Field_Data\MT" outputFolder = r"C:\tmp\Shp_merged" dst = r'Q:\GIS\Field_Data\z_archive\PMM'

    #shutil.copytree(masterFolder, dst + time.strftime('%m_%d_%y'))


    #collect a list of subfolders in master folder
    arcpy.env.workspace = masterFolder
    arcpy.ListWorkspaces('','Folder')
    subfolderLst = arcpy.ListWorkspaces('','Folder')
    print subfolderLst
    for subfolder in subfolderLst:
        arcpy.env.workspace = subfolder
        fcLst = arcpy.ListFeatureClasses()

        for fc in fcLst:
            #file = fc in fcLst
            filename = "'" + arcpy.env.workspace + os.sep + fc + "'"
            print filename
            arcpy.AddField_management(fc, 'shpname','text')
            arcpy.CalculateField_management(fc, 'shpname', filename, "PYTHON" )


except:
    print arcpy.GetMessages()
        # Get the traceback object '"' + wildcard + '"'
    tb = sys.exc_info()[2]
    tbinfo = traceback.format_tb(tb)[0]


    pymsg = tbinfo + "\n" + str(sys.exc_type)+ ": " + str(sys.exc_value)


    arcpy.AddError(pymsg)


    print pymsg

    if __name__ == '__main__':
       main()