CODEWITHSUNDEEP
python
Adrian Statescu
Adrian Statescu

Reputation: 99

Array of complex numbers in Python

How do I make an array of complex numbers in Python?

In C++ STL we can write the following code:

class Complex {

      public:
      int re, 
          im;

      float getModule() {

            return sqrt(re * re + im * im);
      } 
};

vector< Complex > vec;

but in Python?

Upvotes: 1

Views: 16983

Answers (6)

Yelrew
Yelrew

Reputation: 31

A pure Python approach:

array_size = 10
vec = [complex()] * array_size

This will create a list of 10 empty complex numbers.

You can then set the first and second elements, if you want,

vec[0] = complex(2. , 2.,)   # complex number 2+2j
vec[1] = 2 + 2j

or append a new element to your list:

vec.append(3 + 3j)

Upvotes: 0

Adrian Statescu
Adrian Statescu

Reputation: 99

Actually, I want to sort numbers complex according to their module. This is my turn.

import math

class Complex:
  def __init__( self, a, b ): 
      self.a = a
      self.b = b

  def getModule( self ):
      return math.sqrt( self.a**2 + self.b**2 )

  def __str__( self ):
  ''' Returns complex number as a string '''
      return '(%s + i %s)' % (self.a, self.b)

  def add(self, x, y):
      return Complex(self.a + x, self.b + y) 

  def sub(self, x, y):
      return Complex(self.a - x, self.b - y) 


  #input = [[2, 7],[5, 4],[9, 2],[9, 3],[7, 8], [2, 2], [1, 1]]

  # Read the input from a given file complex.in, 
  # in fact is a matrix with Nx2 dimensions
  # first  line re1 im1 
  # second line re2 im2
  # ...
  #Example complex.in
  #5
  #2 7
  #5 4
  #9 2
  #9 3
  #7 8

  f = open('complex.in','r')

  input = [map(int, line.split(' ')) for line in f]

  del input[0]

  num = len( input )

  complexes = [ Complex( i[ 0 ], i[ 1 ] ) for i in input ]

  def swapp(c, a, b):

      c[ a ], c[ b ] = c[ b ], c[ a ] 

  def sort( c ):

      swapped = 1

      for i in range(num - 1, 0, -1):

      swapped = 1

      for j in range(0, i):

          if c[ j ].getModule() > c[ j + 1 ].getModule():

             swapped = 0

             swapp(c, j, j + 1)

      if swapped:

         break   

  sort( complexes )

  f = open('complex.out','w')

  for c in complexes:

      f.write('%s\n' % c)     
      print c

Upvotes: -3

PM 2Ring
PM 2Ring

Reputation: 55479

You can use the built-in complex class.

Or just use a complex literal: Python uses j for the imaginary unit.

z = complex(3, 4)
print(z, z.real, z.imag)

z = 3 + 4j
print(z)

output

(3+4j) 3.0 4.0
(3+4j)

The complex constructor also takes keyword arguments, so you can do

z = complex(real=3, imag=4)

with the args in either order. And that also means that you can even pass the args in a dict, if you want:

d = {'real': 3, 'imag': 4}
z = complex(**d)

There's also a built-in cmath module for mathematical functions of complex arguments.

Upvotes: 0

Marcus M&#252;ller
Marcus M&#252;ller

Reputation: 36352

Extremely simple:

Python's has both a native list and a native complex type, so:

c = complex(real,imag)

or just

c = 1 + 2j

does the trick of creating one;

complexes = [ complex(i, i) for i in range(100) ]

creates thousand complex values in a list complexes.

You might want to have a look at numpy:

import numpy
arr = numpy.ndarray(1000, dtype=numpy.complex128)

Upvotes: 2

syntagma
syntagma

Reputation: 24334

Python has built-in support for complex numbers. You can just enter them like that:

>>> a = 2 + 3j # or: complex(2,3)
>>> a
(2+3j)
>>> type(a)
<type 'complex'>
>>> a.real
2.0
>>> a.imag
3.0
>>>

As for the container, in Python you can start with a list:

>>> complex_nums_list = [2+3j, 3+4j, 4+5j]
>>> complex_nums_list
[(2+3j), (3+4j), (4+5j)]

Or you can use numpy.array, which would be more suited for numerical applications.

Upvotes: 3

Open AI - Opting Out
Open AI - Opting Out

Reputation: 24133

You just create the list of values:

vec = [1+2j, 3+4j]

Upvotes: 0

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