App: Random Module#

The random module allows for the selection of random numbers or elements from a distribution or sequence.

  • First, you need to import the random module.

import random

Methods#

You can access the list of methods in the random module by using the dir(random) function.

  • You can execute help(random) for more details.

print(dir(random))

['BPF', 'LOG4', 'NV_MAGICCONST', 'RECIP_BPF', 'Random', 'SG_MAGICCONST', 'SystemRandom', 'TWOPI', '_ONE', '_Sequence', '_Set', '__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', '_accumulate', '_acos', '_bisect', '_ceil', '_cos', '_e', '_exp', '_floor', '_index', '_inst', '_isfinite', '_log', '_os', '_pi', '_random', '_repeat', '_sha512', '_sin', '_sqrt', '_test', '_test_generator', '_urandom', '_warn', 'betavariate', 'choice', 'choices', 'expovariate', 'gammavariate', 'gauss', 'getrandbits', 'getstate', 'lognormvariate', 'normalvariate', 'paretovariate', 'randbytes', 'randint', 'random', 'randrange', 'sample', 'seed', 'setstate', 'shuffle', 'triangular', 'uniform', 'vonmisesvariate', 'weibullvariate']

choice()#

It returns a randomly chosen element from a non-empty sequence. The syntax is random.choice(sequence).

  • If the sequence is empty, it raises an error.

rand_element = random.choice(['a', 'b', 'c', 'd'])
print(rand_element)

c

choices()#

It returna a list of randomly chosen k elements chosen from a sequence with replacement. The syntax is random.choice(sequence).

  • If the sequence is empty, it raises an error.

rand_list = random.choices(['a', 'b', 'c', 'd'], k=3)
print(rand_list)

['a', 'b', 'a']

randint()#

It returns an integer in a given range. The syntax is random.randint(a, b).

  • The number is chosen between a and b.

rand_int = random.randint(3,8)
print(rand_int)

7

random()#

It returns a float (decimal) number between 0 and 1. The syntax is random.random()

rand_float = random.random()
print(rand_float)

0.771510749411213

randrange()#

It returns a random integer within the specified range. The syntax is:

  • random.randrange(stop): Produces a random integer between 0 and stop-1.

  • random.randrange(start, stop[, step]): Generates a random integer between start and stop-1 with the specified step size.

It is equivalent to random.choice(range(start, stop, step)).

  • The following code returns an integer between 0 and 19.

rand_int = random.randrange(20)
print(rand_int)

4

  • The following code returns an integer from the set: 1, 4, 7, 10, 13, 16, 19.

rand_int = random.randrange(1,20,3)
print(rand_int)

10

uniform()#

It returns a float (decimal) number in a given range. The syntax is random.uniform(a, b).

  • The number is chosen between a and b.

  • The following code returns a float number between 5 and 8.

rand_float = random.uniform(5,8)
print(rand_float)

6.7841424232543

seed()#

It fixes the random number generator. The syntax is random.seed(integer).

  • Fixing the seed ensures that the same random numbers or elements are chosen whenever the code is executed.

  • It takes an integer as its parameter.

  • The value 42 is often chosen for this purpose.

  • 42 is chosen because it is the answer to the Ultimate Question of Life, the Universe, and Everything in Douglas Adams’ book “The Hitchhiker’s Guide to the Galaxy”.

  • When the code below is run, the output may vary each time it’s executed.

rand_element = random.choice(['a', 'b', 'c', 'd'])
print(rand_element)

c

  • When the code below is executed, the output will be same each time it’s executed.

random.seed(0)
rand_element = random.choice(['a', 'b', 'c', 'd'])
print(rand_element)

d

sample()#

  • It returns a sample from a given population.

  • The syntax is random.sample(population, k) where:

    • population represents the entire set from which the sample is to be drawn.

    • k denotes the size of the sample to return.

  • The function returns a new list containing elements randomly picked from the population.

  • The sample elements are selected without replacement, meaning each element can only be chosen once, ensuring all elements in the sample are unique.

sample = random.sample(['a', 'b', 'c', 'd'], k=3)
print(sample)

['d', 'a', 'b']

shuffle()#

It shuffles a mutable sequence. The syntax is random.shuffle(sequence).

  • sequence is modified.

letters = ['a', 'b', 'c', 'd']
random.shuffle(letters)
print(letters)

['a', 'c', 'b', 'd']