Python Programming for Biology: Bioinformatics and Beyond

The ‘

random

’ module

The following table lists some of the more general methods of the random module, which

is used to generate pseudorandom numbers. It should be noted that for testing purposes it

may  be  useful  to  use  random.seed()  with  a  fixed  value  to  get  a  reproducible  set  of

apparently random numbers.

Method

(random.)

Description

seed(x)

Sets an initialising seed number for the (pseudo)random

number generator. Defaults to use the current time as the

seed. Using a fixed seed allows for the same pseudorandom

sequence to be generated.

randint(start, end)

Generates a random integer value from a specified range.

Note that the start and end of the range is included.

choice(vals)

Retrieves a random item from a list or other ordered

collection.

shuffle(vals, func)

Randomly changes the order of items in a list (or other

mutable sequence). Optional argument to specify a specific

random number [0–1] generating function.

sample(vals, num)

Randomly selects a number of items from a list or generator,

without replacement. Leaves the original list unaltered.

random()

Generates a random floating number between zero and one

(interval [0,1]), using a uniform probability distribution.

uniform(start,

Generates a random floating number from between specified

---

end)

bounds, using a uniform probability distribution.

normalvariate(mu,

sigma)

Generates a random numbers with a normal/Gaussian

probability distribution of specified mean and standard

deviation.