Python’s built-in abs(x) function returns the absolute value of the argument x that can be an integer, float, or object implementing the __abs__() function. For a complex number, the function returns its magnitude. The absolute value of any numerical input argument -x or +x is the corresponding positive value +x.
| Argument | x |
int, float, complex, object with __abs__() implementation |
| Return Value | |x| |
Returns the absolute value of the input argument. Integer input –> Integer output Float input –> Float output Complex input –> Complex output |
Interactive Code Shell
Example Integer abs()
The following code snippet shows you how to use the absolute value 42 of a positive integer value 42.
# POSITIVE INTEGER
x = 42
abs_x = abs(x) print(f"Absolute value of {x} is {abs_x}")
# Absolute value of 42 is 42
The following code snippet shows you how to use the absolute value 42 of a negative integer value -42.
# NEGATIVE INTEGER
x = -42
abs_x = abs(x) print(f"Absolute value of {x} is {abs_x}")
# Absolute value of -42 is 42
Example Float abs()
The following code snippet shows you how to use the absolute value 42.42 of a positive integer value 42.42.
# POSITIVE FLOAT
x = 42.42
abs_x = abs(x) print(f"Absolute value of {x} is {abs_x}")
# Absolute value of 42.42 is 42.42
The following code snippet shows you how to use the absolute value 42.42 of a negative integer value -42.42.
# NEGATIVE FLOAT
x = -42.42
abs_x = abs(x) print(f"Absolute value of {x} is {abs_x}")
# Absolute value of -42.42 is 42.42
Example Complex abs()
The following code snippet shows you how to use the absolute value of a complex number (3+10j).
# COMPLEX NUMBER
complex_number = (3+10j)
abs_complex_number = abs(complex_number) print(f"Absolute value of {complex_number} is {abs_complex_number}")
# Absolute value of (3+10j) is 10.44030650891055
Python abs() vs fabs()
Python’s built-in function abs(x) calculates the absolute number of the argument x. Similarly, the fabs(x) function of the math module calculates the same absolute value. The difference is that math.fabs(x) always returns a float number while Python’s built-in abs(x) returns an integer if the argument x is an integer as well. The name “fabs” is shorthand for “float absolute value”.
Here’s a minimal example:
x = 42 # abs()
print(abs(x))
# 42 # math.fabs()
import math
print(math.fabs(x))
# 42.0
Python abs() vs np.abs()
Python’s built-in function abs(x) calculates the absolute number of the argument x. Similarly, NumPy’s np.abs(x) function calculates the same absolute value. There are two differences: (1) np.abs(x) always returns a float number while Python’s built-in abs(x) returns an integer if the argument x is an integer, and (2) np.abs(arr) can be also applied to a NumPy array arr that calculates the absolute values element-wise.
Here’s a minimal example:
x = 42 # abs()
print(abs(x))
# 42 # numpy.abs()
import numpy as np
print(np.fabs(x))
# 42.0 # numpy.abs() array
a = np.array([-1, 2, -4])
print(np.abs(a))
# [1 2 4]
abs and np. absolute are completely identical. It doesn’t matter which one you use. There are several advantages to the short names: They are shorter and they are known to Python programmers because the names are identical to the built-in Python functions.
Summary
The abs() function is a built-in function that returns the absolute value of a number. The function accepts integers, floats, and complex numbers as input.
If you pass abs() an integer or float, n, it returns the non-negative value of n and preserves its type. In other words, if you pass an integer, abs() returns an integer, and if you pass a float, it returns a float.
# Int returns int
>>> abs(20)
20
# Float returns float
>>> abs(20.0)
20.0
>>> abs(-20.0)
20.0
The first example returns an int, the second returns a float, and the final example returns a float and demonstrates that abs() always returns a positive number.
Complex numbers are made up of two parts and can be written as a + bj where a and b are either ints or floats. The absolute value of a + bj is defined mathematically as math.sqrt(a**2 + b**2). Thus, the result is always positive and always a float (since taking the square root always returns a float).
>>> abs(3 + 4j)
5.0
>>> math.sqrt(3**2 + 4**2)
5.0
Here you can see that abs() always returns a float and that the result of abs(a + bj) is the same as math.sqrt(a**2 + b**2).
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