Random number generation is the process of generating a number that cannot be predicted better than by a random chance. Random numbers are used in cryptography, electronic noise simulation and gambling etc.

Most computer generate pseudo random numbers which are not true random numbers. They use algorithms to generate random numbers.

Python uses Mersenne Twister algorithm for random number generation. In python pseudo random numbers can be generated by using random module.

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**Example**

from random import *

print random()

output: It will generate a pseudo random floating point number between 0 and 1.

from random import *

print randint(10, 100)

output: It will generate a pseudo random integer in between 10 and 100

from random import *

print uniform(1, 10)

output: It will generate a pseudo random floating point number between 1 and 10.

import random

list = ['1','4','7','Hi']

print random.choice(list)

output: It will output any of the four objects in the list randomly.

import random

list = [1,2,3,"4", "l90", "hi"]

random.shuffle(list)

print (list)

output: It will shuffle the list and randomly and print the shuffled list.

import random

for i in xrange(5):

print random.randrange(0, 100, 2)

output: It will output 5 random numbers from range 0 to 100. 2 is the step need to be added into randomness. The syntax is random.randrange( start, stop, step )

import random

str = "helloworld"

list = ['a','b','c','d','e','f','o','l']

print random.sample(str, 4)

print random.sample(list, 4)

output: It will output a list of 4 random characters from string and list. The syntax is random.sample (sequence, length)

Sample output:

['o', 'h', 'l', 'w'] ['f', 'b', 'c', 'a']

Frequently Asked Python Interview Questions & Answers

A seed is a number that is used to initialize a pseudo random number generator. Seed guarantees that if you start from same seed you will get the same sequence of random numbers.

import random random.seed(5) print(random.random()) print(random.random()) print(random.random())

output:

0.62290169489 0.741786989261 0.795193565566

**Related Page: Introduction To Python Programming**

**List of Functions in Python Random Module**

seed(a=None, version=2) | Initialize the random number generator |

getstate() | Returns an object capturing the current internal state of the generator |

setstate(state) | Restores the internal state of the generator |

getrandbits(k) | Returns a Python integer with k random bits |

randrange(start, stop[, step]) | Returns a random integer from the range |

randint(a, b) | Returns a random integer between a and b inclusive |

choice(seq) | Return a random element from the non-empty sequence |

shuffle(seq) | Shuffle the sequence |

sample(population, k) | Return a k length list of unique elements chosen from the population sequence |

random() | Return the next random floating point number in the range [0.0, 1.0) |

uniform(a, b) | Return a random floating point number between a and b inclusive |

triangular(low, high, mode) | Return a random floating point number between low and high, with the specified mode between those bounds |

betavariate(alpha, beta) | Beta distribution |

expovariate(lambd) | Exponential distribution |

gammavariate(alpha, beta) | Gamma distribution |

gauss(mu, sigma) | Gaussian distribution |

lognormvariate(mu, sigma) | Log normal distribution |

normalvariate(mu, sigma) | Normal distribution |

vonmisesvariate(mu, kappa) | Vonmises distribution |

paretovariate(alpha) | Pareto distribution |

weibullvariate(alpha, beta) | Weibull distribution |

Python 3.x.x added a new secret module for generating secure random. It has three functions. Let’s see the example below.

**Example**

import secrets import string letters = string.ascii_letters + string.digits password = ''.join(secrets.choice(letters) for i in range(10)) print(password)

**output:** it will print a 10-digit alphanumeric string with combination of uppercase and lower case letters.

import secrets num = secrets.randbelow(10) print(num) output: randomly prints a number below given range import secrets num = secrets.randbits(3) print(num)

output: This will print a random number of given bit

**Tokens**

To generate a more complex random string use token_hex(bytes)

import secrets

token = secrets.token_hex(16)

print(token)

More secure string generation with os.urandom

import os

os.urandom(8)

output: It will give an 8-byte system random number. [sample: 'xcfx8bPWxa7xdfx01' ]

import os, binascii

output = os.urandom(8)

hex = binascii.hexlify(output)

print (hex)

**output:** It will give the hex value. [sample: 25d6f3739e32cbf7]

secret module generates more secure random and it is available in python 3.x.

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