Python Abs Function
When working with numbers in Python, you may need to know how far a value is from zero, regardless of whether it is positive or negative. This is a common requirement in many situations, such as calculating distances, measuring errors, or comparing values without considering their sign. Instead of writing custom code to handle positive and negative numbers, Python provides a built-in function: abs().
What is abs(), and when/why is it used?
The abs() function is used to find the absolute value of a number. The absolute value is the distance of a number from zero on the number line, always as a non-negative value. This is useful whenever you want to ignore the sign of a number and focus only on its magnitude. For example, you might use abs() to calculate the difference between two values, regardless of which is larger, or to ensure that a distance or error measurement is always positive.
Both beginners and experienced programmers use abs() to write clearer, more reliable code when working with numbers that can be either positive or negative.
Basic Syntax
The abs() function takes a single argument:
number: An integer, float, or complex number.
abs(number)
Examples with integers, floats, and complex numbers
Let's see how abs() works with different types of numbers in Python. The function always returns a non-negative result, regardless of the input's sign.
print(abs(-5)) # Output: 5
print(abs(3.14)) # Output: 3.14
print(abs(-2.7)) # Output: 2.7
print(abs(0)) # Output: 0
- For integers and floats,
abs()simply removes the sign. For example,abs(-5)returns5, andabs(-2.7)returns2.7. If the number is already positive or zero, it stays the same.
abs() can also be used with complex numbers. In this case, it returns the magnitude (distance from zero in the complex plane):
# With complex numbers, returns the magnitude
z = 3 - 4j
print(abs(z)) # Output: 5.0 (since sqrt(3**2 + 4**2) = 5)
- For a complex number like
3 - 4j, the magnitude is calculated using the Pythagorean theorem:sqrt(3**2 + 4**2) = 5.
How could you implement abs() manually?
Although abs() is built-in, it's helpful to see how you could write your own version for real numbers:
def my_abs(number):
if number >= 0:
return number
else:
return -number
- The function checks if the number is greater than or equal to zero. If so, it returns the number as is. Otherwise, it returns the opposite (which makes it positive).
Understanding this logic helps you see why abs() always returns a non-negative value, no matter the input.
Summary
abs()returns the distance from zero (always non-negative).- Works with int, float, and complex numbers.
- For complex numbers, returns the magnitude.