具有相同名称的多个字段的对象

Question

#concat 30 files
files = glob.glob('files/*.csv')
#order of files is important for concat values - 
#in first file are id = (1,100), second (101, 200)...
print (files)

#set by max rows of file
N = 100
#loop by big fileby chunk define in N
for i, x in enumerate(pd.read_csv('files/big.csv', chunksize=N, index_col=['id'])):
    #added try for avoid errors if want seelct non exist file in list files
    try:
        df = pd.read_csv(files[i], index_col=['id'])
        df1 = pd.concat([x, df], axis=1)
        print (df1)
        #in first loop create header in output
        if i == 0:
            pd.DataFrame(columns=df1.columns).to_csv('files/out.csv')
        #append data to output file
        df1.to_csv('files/out.csv', mode='a', header=False)

    except IndexError as e:
        print ('no files in list')

/ ** 题） 嗨，我是一个java初学者，甚至不确定这是否是一个适当的问题在这里问，但我不明白为什么打印（D.sf，C.sf，B.sf）;为C.sf.给出304。我以为会是342.

提前感谢您的帮助。 * /