<pre><code>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
</code></pre>