Convert Series' Index into a Dataframe Column

mubashir_rizvi · February 16, 2023, 6:00pm

Several methods are there for converting an index of a Pandas Series into a DataFrame column and this thread covers a few of them. One can consider any approach depending on the desired outcomes. Before getting into the methods, if you are unfamiliar with what Series and DataFrames are, you can have an overview of Merge many series to create a dataframe thread after which you’ll have a good idea of what these objects are and how they differ from each other. Lets now dive into the methods:

1. Using "reset_index()" method on a series:

The reset_index() method is used to reset the index of a Pandas DataFrame or Series object, it adds a new sequential index in the object and converts its previous index into a column named index by default.

This creates a data frame with two columns; index which is the original index of the Series and a column containing the values of the series which is named by itself.

2. Using "to_frame()" method along with 'reset_index()' method:

The to_frame() method converts the one-dimensional data structure of Series into a two-dimensional Pandas DataFrame object. What actually happens:

to_frame converts the Series into a DataFrame object.
The DataFrame has 1 column containing the values of the Series, and an index the same as the index of the Series.
reset_index() converts the index into a column and resets the index to a new sequential one.

This will also create a data frame with two columns; index which is the original index of the Series and a column containing the values of the series which is named by itself.

3. Using "reset_index()" method with "rename()" method:

The rename() function is helpful in providing new labels to the index or columns of Pandas objects.
In this sample code, it is used to rename the new columns created after the conversion of the Series object into a DataFrame object.

4. Using "assign()" method:

Another way to convert a series’ index into a data frame column is to use the assign() method. This method adds a new column to the data frame with the index of the series.
It works on a data frame object so we first convert the Series into a DataFrame using the to_frame() method.
Then we use assign() to assign the series’ index to a column named series_index.