5 Best Ways to Check if a Number is Whole in Python

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💡 Problem Formulation: Python developers often need to determine if a given numerical value represents a whole number. A whole number, belonging to the set of nonnegative integers (0, 1, 2, …), doesn’t have a fractional or decimal component. For instance, ‘7’ is a whole number, whereas ‘7.5’ is not. This article’s aim is to introduce five reliable methods to check if the input number is whole in Python, enhancing code robustness in numerical computations.

Method 1: Using the is_integer() Method on Floats

This method involves converting the number to a float (if it isn’t already) and then using the is_integer() method, which returns True if the number is a whole number and False otherwise. It is efficient and built into the float type in Python.

Here’s an example:

num = 7.0
result = num.is_integer()
print(result)

Output: True

This code converts the variable num to a float and checks if it represents a whole number using the is_integer() method. The output ‘True’ indicates that ‘7.0’ is indeed a whole number. This method is quick, but it requires the number to be in float format, which may not be suitable in all situations.

Method 2: Using Modulo Operator

By employing the modulo operator %, we can check if the remainder of the division of the number by 1 is zero, which indicates a whole number. This method is versatile as it works with both integers and floats.

Here’s an example:

num = 7
result = (num % 1 == 0)
print(result)

Output: True

In this example, using the modulo operator determines if num is a whole number. Since 7 divided by 1 leaves no remainder, the expression evaluates to True. This technique works regardless of whether num is an integer or a float type.

Method 3: Comparing with Rounded Value

This method checks if a number is whole by comparing it with its rounded counterpart using the round() function. If both values are equal, the number is whole.

Here’s an example:

num = 7.5
result = (num == round(num))
print(result)

Output: False

The code snippet compares num with its rounded value. Since 7.5 rounds to 8 and the numbers are not equal, result is False, meaning 7.5 is not a whole number. This method is simple to understand and implement but may have issues with floating-point precision for very large numbers.

Method 4: Using Integer Type Casting

Checking whole numbers can also be done by converting the number to an integer and back to a float and comparing it with the original number. If they match, the number is whole.

Here’s an example:

num = 7.0
result = (num == float(int(num)))
print(result)

Output: True

The code sets num to a float, casts it to integer, which truncates any decimal part, casts it back to float, and compares it to the original. Since 7.0 remains unchanged through this process, the outcome is True, confirming that the number is whole.

Bonus One-Liner Method 5: Using the math.trunc() Function

One-liner checks for whole numbers can be achieved using the math.trunc() function, which truncates the decimal part of the number, akin to casting to int, and then compare the result to the original number.

Here’s an example:

import math
num = 7.0
result = (num == math.trunc(num))
print(result)

Output: True

By importing the math module and using math.trunc(), we truncate the decimal of num and verify if it equals the original number. The equality implies that num is a whole number.

Summary/Discussion

  • Method 1: is_integer() Method. Direct and pythonic. Limited to float types only.
  • Method 2: Modulo Operator. Flexible and works with any numeric type. Can be less intuitive for beginners.
  • Method 3: Comparing with Rounded Value. Understandable and simple. Precision issues with very large numbers.
  • Method 4: Integer Type Casting. Robust and general. Requires double casting, which can be inefficient.
  • Method 5: math.trunc() Function. Concise one-liner. Depends on the math module and can be less transparent for beginners.