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Python: complex() function

complex() function

The complex() function is used to create a complex number or convert a string or number to a complex number.

The complex type is described in Numeric Types — int, float, complex.

Syntax: 

complex([real[, imag]])
Python: Built-in function - complex function()

Version:

(Python 3)

If the first parameter is a string, it will be interpreted as a complex number and the function must be called without a second parameter.

The second parameter can never be a string. Each argument may be any numeric type (including complex).

If imag is omitted, it defaults to zero and the function serves as a numeric conversion function like int() and float(). If both arguments are omitted, returns 0j.

Return value:

Return a complex number with the value real + imag*1j or convert a string or number to a complex number.

Note: When converting from a string, the string must not contain whitespace around the central + or - operator. For example, complex('1+2j') is fine, but complex('1 + 2j') raises ValueError.

Example: Create a complex number in Python

x = complex(3, -5)
print(x)
x = complex(1)
print(x)
x = complex()
print(x)
x = complex('6-7j')
print(x)

Output:

(3-5j)
(1+0j)
0j
(6-7j)

Pictorial Presentation:

Python: Built-in-function - complex() function

Pictorial Presentation:

Python: Built-in-function - complex() function

Example: Create complex Number Without Using complex()

x = 3+5j
print('x =',x)
print('Type of x is',type(x))

y = -5j
print('y =',y)
print('Type of y is',type(x))

z = 0j
print('z =',z)
print('Type of z is',type(z))

Output:

x = (3+5j)
Type of x is 
y = (-0-5j)
Type of y is 
z = 0j
Type of z is

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Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m