pandas Reindexing

Reindexing

In [91]: obj = pd.Series([4.5, 7.2, -5.3, 3.6], index=['d', 'b', 'a', 'c'])
In [92]: obj
Out[92]:
d 4.5
b 7.2
a -5.3
c 3.6
dtype: float64

In [93]: obj2 = obj.reindex(['a', 'b', 'c', 'd', 'e'])
In [94]: obj2
Out[94]:
a -5.3
b 7.2
c 3.6
d 4.5
e NaN
dtype: float64

In [95]: obj3 = pd.Series(['blue', 'purple', 'yellow'], index=[0, 2, 4])
In [96]: obj3
Out[96]:
0 blue
2 purple
4 yellow
dtype: object

In [97]: obj3.reindex(range(6), method='ffill')
Out[97]:
0 blue
1 blue
2 purple
3 purple
4 yellow
5 yellow
dtype: object

In [98]: frame = pd.DataFrame(np.arange(9).reshape((3, 3)),
....: index=['a', 'c', 'd'],
....: columns=['Ohio', 'Texas', 'California'])
In [99]: frame
Out[99]:
Ohio Texas California
a 0 1 2
c 3 4 5
d 6 7 8

In [102]: states = ['Texas', 'Utah', 'California']
In [103]: frame.reindex(columns=states)
Out[103]:
Texas Utah California
a 1 NaN 2
c 4 NaN 5
d 7 NaN 8

In [104]: frame.loc[['a', 'b', 'c', 'd'], states]
Out[104]:
Texas Utah California
a 1.0 NaN 2.0
b NaN NaN NaN
c 4.0 NaN 5.0
d 7.0 NaN 8.0