import pandas as pd
import glob
import os
path = 'Downloads/cistrome_hg38/hg38_cismotifs/'
filelist = glob.glob(path + "/*")
print (filelist[1])
frame = pd.DataFrame()
for file in filelist:
    df2 = pd.read_csv(file,sep='\t')
    df2.columns = ['chr','start','end','score']
    factorname = os.path.basename(file)
    df2['factor'] = factorname
    frame=frame.append(df2,ignore_index=True)