How to Handle Placeholders in Python's Format Method

The format() method lets you create a template for displaying text.

Example

string = "My name is {0} and I live in {1}".format("Andrea", "Rome")

This will result in the string:

'My name is Andrea and I live in Rome'

So far, so good. The method is useful, but nothing special yet.

However, the format method has a lot of potential because you can apply different formatting to each placeholder.

Working with Placeholders

To format a placeholder, you add a colon after the parameter name.

To the right of the colon, you can include various formatting options.

:> right alignment
:< left alignment
:* fill with spaces
:5.3f format as a real number
:c character
:n format as a locale-specific number
:b binary value
:d decimal value
:o octal value
:x hexadecimal value
:X uppercase hexadecimal value

Practical Examples

Example 1

string = "The number {0:d} in binary is {0:b}".format(5)

The resulting string is:

'The number 5 in binary is 101'

Example 2

You can format real numbers with a custom template.

string = "The total cost is {0:*10.3f}".format(1234.56789)

The result is:

'The total cost is 1234.568'

Example 3

You can also align text to the right or left, filling in the empty spaces with a character of your choice.

string = "The total cost is {0:*>10.3f}".format(1234.56789)

The result is:

'The total cost is **1234.568'