问使用Pandas导入文件时的列问题

EN

data= np.genfromtxt('/path/hubel.dat')
df=pd.DataFrame(data)
df.columns= ['Z', 'H', 'err']
df_groupby_err=df.groupby("err")
for err, H  in df.groupby("err"):
    if err<20:
        print( )
        print( H )
        print( ) 
f=open("hubble_error_edited-2.txt", "w")
for err, H in df.groupby("err"):
    if err<20:
        f.write("\n"+str(H)+""+ "\n")
f.close()
data= pd.read_csv("/path/hubble_error_edited-2.txt" )