我正在尝试从csv文件中获取唯一值。下面是该文件的一个示例：

12,life,car,good,exellent
10,gift,truck,great,great
11,time,car,great,perfect

新文件中所需的输出如下：

12,10,11
life,gift,time
car,truck
good.great
excellent,great,perfect

下面是我的代码：

def attribute_values(in_file, out_file):
    fname = open(in_file)
    fout = open(out_file, 'w')

    # get the header line
    header = fname.readline()
    # get the attribute names
    attrs = header.strip().split(',')

    # get the distinct values for each attribute
    values = []
    
    for i in range(len(attrs)):
        values.append(set())

    # read the data
    for line in fname:
        cols = line.strip().split(',')
        
        for i in range(len(attrs)):
            values[i].add(cols[i])

        # write the distinct values to the file
        for i in range(len(attrs)):
            fout.write(attrs[i] + ',' + ','.join(list(values[i])) + '\n')

    fout.close()
    fname.close()

代码当前输出如下：

12,10
life,gift
car,truck
good,great
exellent,great
12,10,11
life,gift,time
car,car,truck
good,great
exellent,great,perfect

我该如何解决这个问题？