问题:如何遍历两个 Pandas 列?

考虑:

In [35]: test = pd.DataFrame({'a':range(4),'b':range(4,8)})

In [36]: test
Out[36]:
   a  b
0  0  4
1  1  5
2  2  6
3  3  7

In [37]: for i in test['a']:
   ....:  print i
   ....:
0
1
2
3

In [38]: for i,j in test:
   ....:  print i,j
   ....:
------------------------------------------------------------
Traceback (most recent call last):
  File "<ipython console>", line 1, in <module>
ValueError: need more than 1 value to unpack


In [39]: for i,j in test[['a','b']]:
   ....:  print i,j
   ....:
------------------------------------------------------------
Traceback (most recent call last):
  File "<ipython console>", line 1, in <module>
ValueError: need more than 1 value to unpack


In [40]: for i,j in [test['a'],test['b']]:
   ....:  print i,j
   ....:
------------------------------------------------------------
Traceback (most recent call last):
  File "<ipython console>", line 1, in <module>
ValueError: too many values to unpack

解答

使用DataFrame.itertuples()方法:

for a, b in test.itertuples(index=False):
    print a, b