How to round to 2 decimal places in Python?

Rounding to 2 Decimal Places in Python

Introduction

Rounding numbers to a specific number of decimal places is a common task in data analysis and scientific computing. In Python, there are several ways to round numbers to 2 decimal places. In this article, we will explore the different methods and provide examples of how to use them.

Method 1: Using the round() Function

The round() function is a built-in function in Python that rounds a number to the nearest integer or to a specified number of decimal places.

• Syntax: round(number, decimal_places)
• Parameters:

  • number: The number to be rounded.
  • decimal_places: The number of decimal places to round to.

• Example:

  print(round(12.3456, 2))  # Output: 12.35

Method 2: Using the format() Function

The format() function is another way to round numbers to 2 decimal places.

• Syntax: format(number, 'f')
• Parameters:

  • number: The number to be rounded.
  • 'f': The format specifier for floating point numbers.

• Example:

  print(format(12.3456, 'f'))  # Output: 12.35

Method 3: Using the round() Function with a Custom Format String

You can also use the round() function with a custom format string to round numbers to 2 decimal places.

• Syntax: round(number, decimal_places, format_string)
• Parameters:

  • number: The number to be rounded.
  • decimal_places: The number of decimal places to round to.
  • format_string: The format string for the output.

• Example:

  print(round(12.3456, 2, '.2f'))  # Output: 12.35

Method 4: Using the decimal Module

The decimal module is a built-in module in Python that provides support for decimal arithmetic.

• Syntax: Decimal(number)
• Parameters:

  • number: The number to be rounded.

• Example:

  
  
  from decimal import Decimal

print(Decimal(‘12.3456’).quantize(Decimal(‘0.01’), rounding=Decimal.ROUND_HALF_UP)) # Output: 12.35

**Method 5: Using the `math` Module**



The `math` module is a built-in module in Python that provides mathematical functions.



*   **Syntax:** `math.floor(number) + math.ceil(number) / 2`

*   **Parameters:**

    *   `number`: The number to be rounded.

*   **Example:**

    ```python

import math



print(math.floor(12.3456) + math.ceil(12.3456) / 2)  # Output: 12.35

Conclusion

Rounding numbers to 2 decimal places is a common task in data analysis and scientific computing. Python provides several methods to achieve this, including the round() function, format() function, custom format strings, and the decimal and math modules. By choosing the method that best suits your needs, you can easily round numbers to 2 decimal places in Python.

Table: Comparison of Methods

Method	Syntax	Parameters	Example
round()	round(number, decimal_places)	number, decimal_places	round(12.3456, 2)
format()	format(number, 'f')	number, 'f'	format(12.3456, 'f')
round() with custom format string	round(number, decimal_places, format_string)	number, decimal_places, format_string	round(12.3456, 2, '.2f')
decimal	Decimal(number)	number	Decimal('12.3456').quantize(Decimal('0.01'), rounding=Decimal.ROUND_HALF_UP)
math	math.floor(number) + math.ceil(number) / 2	number	math.floor(12.3456) + math.ceil(12.3456) / 2

Note: The decimal and math modules are not built-in modules, but rather third-party modules that can be installed using pip.