Compare magnitudes
Normalize signed measurements or offsets before comparison.
Python · Function
abs
abs() returns the absolute value of a number. Complex inputs produce their magnitude, and objects can define custom behavior with __abs__().
How it works
Call abs() with one positional argument to obtain its absolute value. Integers and floating-point values produce their non-negative magnitude, complex values produce their magnitude as a float, and custom objects can define the result through __abs__().
Syntax
abs(number, /)Parameters
| Name | Type | Description |
|---|---|---|
number | integer, floating-point number, complex number, or object implementing __abs__() | A number or object implementing __abs__() whose absolute value or magnitude is requested. |
Returns
The absolute value of the argument; for a complex argument, its magnitude.
Key points
abs()produces a value representing the input's absolute magnitude.- Integer and floating-point arguments are supported.
- Complex inputs yield their magnitude.
- Objects can customize the operation by providing
__abs__().
Common mistakes
- For complex input, the result is magnitude rather than a complex number.
- Custom objects are accepted when they implement
__abs__().
Example: Absolute values of real and complex numbers
print(abs(-42))
print(abs(3 + 4j))The first call returns 42; the second returns the complex number's magnitude, 5.0.
When to use it
Measure complex magnitude
Compute the length of a complex value in the plane.
Support custom numeric types
Provide absolute-value semantics for a domain-specific numeric class.
Interview questions
QWhat does abs() return?
abs(number) returns the absolute value of a number. For a complex argument, it returns the number's magnitude.
Follow-up: What enables custom types to work with abs()? They implement __abs__(), which supplies the value returned by the call.
QWhat kinds of arguments does abs() support?
The function accepts one positional argument. The documented argument may be an integer, a floating-point number, or an object implementing __abs__().
Follow-up: What happens with a complex argument? Its magnitude is returned instead of a complex result.
QHow does abs() interact with custom objects?
A class can define __abs__() so that abs(instance) delegates to that method. This lets the type choose its absolute-value behavior.
Follow-up: How should a custom implementation represent its result? It should return the type's absolute-value result according to the class's numeric semantics.
Related
__abs__()complexfloatint