用python中的特定列名过滤pandas数据框

我有一个熊猫数据框和一个列表，如下所示

I have a pandas dataframe and a list as follows

mylist = ['nnn', 'mmm', 'yyy']
mydata =
   xxx   yyy zzz nnn ddd mmm
0  0  10      5    5   5  5
1  1   9      2    3   4  4
2  2   8      8    7   9  0

现在，我只想获取mylist中提到的列并将其保存为csv文件.

Now, I want to get only the columns mentioned in mylist and save it as a csv file.

即

     yyy  nnn   mmm
0    10     5     5
1    9      3     4
2    8      7     0

我当前的代码如下.

mydata = pd.read_csv( input_file, header=0)

for item in mylist:
    mydata_new = mydata[item]

print(mydata_new)
mydata_new.to_csv(file_name)

在我看来，我的新数据框产生了错误的结果.我在哪里弄错了?请帮帮我！

It seems to me that my new dataframe produces wrong results.Where I am making it wrong? Please help me!