complex() method returns a complex number object. You can either pass a string argument to convert the string to a complex number, or you provide the real and imaginary parts to create a new complex number from those.
This article shows you how to use Python’s built-in
complex() constructor. You’ll not only learn how to use it—but also why it is useless and what you should do instead in newer Python versions.
Learn by example! Here are some examples of how to use the
complex() built-in function:
>>> complex(1, -2) (1-2j) >>> complex(2, -1) (2-1j) >>> complex(2, 2) (2+2j) >>> complex(1) (1+0j) >>> complex(2) (2+0j) >>> complex('42-21j') (42-21j)
You can use the
complex() method with three different argument lists.
complex(real) # Imaginary Part is 0j
complex(real, img) # Both real and imaginary part are given
complex(string) # String has format 'x+yj' for real part x and imaginary part y.
|Arguments||The real part of the complex number|
|The imaginary part of the complex number|
|A string defining the real and imaginary part in the form |
|Return Value||Returns a complex number.|
Interactive Shell Exercise: Understanding Complex()
Consider the following interactive code:
Exercise: Guess the output before running the code.
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How to Create Complex Number Without complex()
Interestingly, you don’t need the
complex() constructor to create a complex number! Instead, newer version of Python have built-in complex number support—just use the the syntax
x+yj for real part
x and imaginary part
y to obtain a complex number.
a = 1+1j b = 4+42j c = 0+0j print('Complex Numbers:') print(a, b, c) print('Types:') print(type(a), type(b), type(c))
The output is:
Complex Numbers: (1+1j) (4+42j) 0j Types: <class 'complex'> <class 'complex'> <class 'complex'>
complex() method returns a complex number object. To create a complex number:
- Pass a string argument to convert the string to a complex number, or
- Provide the real and imaginary parts to create a new complex number from those.
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