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Arithmetic with DataFrame and Series

As we saw before, each column in a DataFrame object is a Series object.

We can do arithmetic between a Series object and a single number. For example:

monthly_salary = df['salary'] / 12

This creates another Series object, and because it has the same length as each one of the columns in the original DataFrame, we can put it into a new column:

df['monthly_salary'] = monthly_salary

If two series are the same size, we can do element-by-element arithmetic with them.

For example:

monthly_taxes = df['monthly_salary'] * df['tax_rate']

This multiplies the monthly salary by the tax rate in each row and returns to you a new Series object. This one also has the same length as each one of the columns and can be assigned into a new column:

df['monthly_taxes'] = monthly_taxes

Exercise:

• Calculate the post-tax annual income and make that into a new column.
• How would you figure out what are the different tax rates in australia and what they boundaries are between these tax rates in terms of annual income?