CANDELS_Combining_Fields_Master.py

from astropy.table import vstack, Table
from astropy.io import ascii

fields = ['COSMOS', 'EGS', 'GOODSN', 'GOODSS', 'UDS']
_Combined_Fields = Table()

for each_field in fields:
    catalog = ascii.read('/Users/laurenhiggins/Dropbox/GEG_Research/Key_Parameters_Catalogs_Per_Field/FOLDER/___.cat'%each_field)
    _subset = catalog[['ID', , ]]
    _subset['Field_flag'] = each_field
    _Combined_Fields = vstack([_Combined_Fields, _subset])

ascii.write(_Combined_Fields, '/Users/laurenhiggins/Dropbox/GEG_Research/Key_Parameters_Catalogs_Per_Field/FOLDER/___.cat', 
            names=('ID', ,'Field_Flag'), format='csv', overwrite=True)