循环遍历列

Question

有人可以告诉我如何在数据框列中循环显示多个值。

示例：

col1    col2
High street qwe.723,qwe.2,qwe.17,qwe.1000,qwe.23
Must street qwe.34,qwe.17,qwe.1000,qwe.23

我希望得到以下输出：

High street
qwe.723
High street
qwe.2
High street
qwe.17
High street
qwe.1000
High street
qwe.23

Must street
qwe.34
Must street
qwe.17
Must street
qwe.1000
Must street
qwe.23

我的尝试：

lines = open('file.txt','r')
for line in lines:
    line=line.strip().split('\t')
    vals=line[1].split(',')
    for val in vals:
        print(line[0],'\n',val)

Answer 1

试试这个：

In [136]: df
Out[136]:
          col1                                  col2
0  High street  qwe.723,qwe.2,qwe.17,qwe.1000,qwe.23
1  Must street         qwe.34,qwe.17,qwe.1000,qwe.23

In [137]: df.set_index('col1').col2.str.split(',', expand=True).stack().reset_index(level=1, drop=1).to_frame('col2').reset_index().stack()
     ...:
Out[137]:
0  col1    High street
   col2        qwe.723
1  col1    High street
   col2          qwe.2
2  col1    High street
   col2         qwe.17
3  col1    High street
   col2       qwe.1000
4  col1    High street
   col2         qwe.23
5  col1    Must street
   col2         qwe.34
6  col1    Must street
   col2         qwe.17
7  col1    Must street
   col2       qwe.1000
8  col1    Must street
   col2         qwe.23
dtype: object

我确信必须有更好的方法来做到这一点......

Answer 2

另一个：

(df.set_index('col1')
   .col2.str.split(',', expand=True)
   .stack()
   .reset_index(level=-1, drop=True)
   .to_csv('output.txt',sep='\n')

Answer 3

因为我正在玩cytoolz和numpy 超快！

import cytoolz

c2 = np.core.defchararray.split(df.col2.values.astype('str'), ',')
col1 = df.col1.values.repeat([len(c) for c in c2.tolist()])
col2 = list(cytoolz.concat(c2))
np.stack([col1, col2]).ravel('F')

array(['High street', 'qwe.723', 'High street', 'qwe.2', 'High street',
       'qwe.17', 'High street', 'qwe.1000', 'High street', 'qwe.23',
       'Must street', 'qwe.34', 'Must street', 'qwe.17', 'Must street',
       'qwe.1000', 'Must street', 'qwe.23'], dtype=object)

时间测试