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I am calling a list of names in from a text file and would like to use each of those to make new layers. I am running into an issue where I get "TypeError: cannot concatenate 'str' and 'list' objects" and am not sure how to get past this. I tried a couple of different where clauses without much luck.

*EDIT: Working code below. The issue was I am calling the file directly in the walk and the list fields. so when I am appending the path I needed to remove the filename from os.path.join(dirpath, filename). 

import arcpy, os
from arcpy import env

#setup input varible
ws = r"M:/"

cl = r"/Admin_1.shp"

dem = r"M:/SRTM/dem"

#set output as a variable
out = r"M:/Elevation_Masks/Masks"
    with open('M:/Elevation_Masks/test_space/elevCountries_Test.txt', 'r') as f:
    cb = [line.strip() for line in f]

CNTRY_NAME_FIELD = 'CNTRY_NAME'

for dirpath, dirnames, filenames in arcpy.da.Walk(cl, datatype="FeatureClass", type="ALL"):
    for filename in filenames:
        if CNTRY_NAME in [f.name for f in arcpy.ListFields(cl)]:
            for country_name in cb:
                print "Country:", country_name
                #setup where clause
                where = '"%s" = \'%s\'' % (CNTRY_NAME, country_name)
                arcpy.Select_analysis(os.path.join(dirpath), r"M:/Elevation_Masks/test_space/Country_Masks_Test/clipLayers_Test/clipLayers_Test.gdb/" + country_name + "_Boundary", where)
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You need to either set cb to the first element of the list of lines cb = [line.strip() for line in f][0] or loop over the list of country names in your file.

with open('M:/Elevation_Masks/elevs.txt', 'r') as f:
    cb = [line.strip() for line in f]

CNTRY_NAME_FIELD = 'CNTRY_NAME'

for dirpath, dirnames, filenames in arcpy.da.Walk(cl, datatype="FeatureClass", type="ALL"):
    for filename in filenames:
        if CNTRY_NAME_FIELD in [f.name for f in arcpy.ListFields(cl)]:
            for country_name in cb:
                print "Country:", country_name
                #setup where clause
                where = '"%s" = \'%s\'' % (CNTRY_NAME_FIELD, country_name)

                arcpy.Select_analysis(os.path.join(dirpath, filename),
                                      r"M:\Elevation_Masks\Masks\clipLayers\" + country_name + "_Boundary",
                                      where)
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  • Thanks for the response! Any reason the shapefiles would come back empty? I tried placing them in a GDB and as shapefiles but they are empty files? – cbrannin Jul 2 '14 at 13:47
  • All I can think is that the selection is somehow null. You're not getting any error messages? – Jason Scheirer Jul 2 '14 at 13:50
  • No, but when I print the country_name I get n as the result. So it has something to do with that I would guess. But one would think an error would be thrown if the selection was wrong. Right? – cbrannin Jul 2 '14 at 14:13
  • I think you applied both of my fixes then, you only need one. Get rid of the [0]. It's a valid where clause so it won't give an error, it just won't return any data. – Jason Scheirer Jul 2 '14 at 14:22
  • Wow! Thanks again for all the help. there were just a couple of small things that were tripping it up. Working code replaced in OP. Thanks again! – cbrannin Jul 2 '14 at 14:43
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Your method assigns CB as a list not the individual lines in the file. Try opening your file like this:

f = open('M:/Elevation_Masks/elevs.txt','r')
for line in f:
    cb = line.strip('\n')
    # Carry on with the loop
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