SELECT, ADD, AND DELETE COLUMNS IN DataFrames

This section contains short code blocks that illustrate how to perform operations on a DataFrame that resemble the operations on a Python dictionary. For example, getting, setting, and deleting columns works with the same syntax as the analogous Python dict operations, as shown here:

df = pd.DataFrame.from_dict(dict([('A',[1,2,3]),('B',[4,5,6])]),
                orient='index', columns=['one', 'two', 'three'])

print(df)

The output from the preceding code snippet is here:

   one  two  three
A    1    2      3
B    4    5      6

Now look at the following operation that appends a new column to the contents of the DataFrame df:

df['four'] = df['one'] * df['two']
print(df)

The output from the preceding code block is here:

   one  two  three  four
A    1    2      3     2
B    4    5      6    20

The following operation squares the contents of a column...