Inserting and deleting columns to a DataFrame

In this section, we will see how to insert and delete columns to a data frame.

Getting ready

Run the following code to load NumPy, and pandas, and to initialize a DataFrame object:

import numpy as np
import pandas as pd
df1 = pd.DataFrame([['Pen', 24, 2.39],
                    ['Eraser', 32, 1.29],
                    ['Sharpener', 12, 10.39],
                    ['Pencil', 42, 0.59 ]],
                   index=[100024, 201024, 202034, 101122],
                   columns = ['item', 'inventory', 'unit_price'])

How to do it...

To insert a column, run the following cell:

df['discount'] = [0.75, 0.50, 0.75, 0.75]

To delete a column, use the following code:

del df['discount']

How it works...

We can think of a DataFrame as a dictionary, where the dictionary keys are the column names. So, to insert a column, we can use the following code:

df['column_name'] = <iterable>

The <iterable> can be for example, a list, a NumPy array, or a pandas Series object...