"vertically" concat a bunch of csv files in Pandas

pandas-csv.py

from pandas import *
import dateutil
import os, os.path

csvdir = os.getcwd()
filenames = [os.path.join(csvdir,csvfile)
             for csvfile in os.listdir(csvdir)
             if csvfile[-4:] == '.csv']
dfs = [io.parsers.read_csv(filename,
                           converters={0:dateutil.parser.parse})
       for filename in filenames]

for (df,name) in zip(dfs, filenames):
    df.columns = ['date','value_of_interest']
    df['filename'] = name
df = concat(dfs, ignore_index=True)