The essential basic functionality

Pandas supports many essential functionalities that are useful to manipulate Pandas data structures. In this book, we will focus on the most important features regarding exploration and analysis.

Reindexing and altering labels

Reindex is a critical method in the Pandas data structures. It confirms whether the new or modified data satisfies a given set of labels along a particular axis of Pandas object.

First, let's view a reindex example on a Series object:

>>> s2.reindex([0, 2, 'b', 3])
0    0.6913
2    0.8627
b    NaN
3    0.7286
dtype: float64

When reindexed labels do not exist in the data object, a default value of NaN will be automatically assigned to the position; this holds true for the DataFrame case as well:

>>> df1.reindex(index=[0, 2, 'b', 3],
        columns=['Density', 'Year', 'Median_Age','C'])
   Density  Year  Median_Age        C
0      244  2000        24.2      NaN
2      268  2010        28.5      NaN
b      NaN   NaN  ...