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Python random Module Overview

The random module is a built-in Python module for working with pseudo-random values.

Beginners often use it to:

  • generate random numbers
  • choose a random item from a list
  • shuffle a list
  • pick several random items

It is useful for games, simple scripts, testing, and practice programs.

It is not the right tool for passwords, secure tokens, or anything security-related. For that, use the secrets module instead.

Quick example #

import random

print(random.randint(1, 10))
items = ["apple", "banana", "cherry"]
print(random.choice(items))

Use randint() for a random whole number in a range, and choice() to pick one item from a list.

What the random module is #

Python’s random module is part of the standard library, so you do not need to install anything.

It gives you functions for:

  • random numbers
  • random choices from sequences
  • random sampling
  • shuffling lists

The values are pseudo-random. That means they are produced by an algorithm, but they behave randomly enough for most beginner programs.

Use random for:

  • small games
  • classroom examples
  • simple automation
  • testing with sample data

Do not use it for:

  • passwords
  • authentication tokens
  • security-sensitive code

When beginners use it most #

Beginners usually use random when they want to:

  • pick a random number in a range
  • choose a random item from a list
  • shuffle a list into a new order
  • pick multiple random items
  • create simple game behavior

For example, you might:

  • roll a die
  • choose a random student name
  • shuffle quiz questions
  • build a number guessing game

Functions to know first #

These are the most common functions in the random module.

random.random() #

Returns a floating-point number from 0.0 up to but not including 1.0.

import random

print(random.random())

Possible output:

0.472918374

Use this when you want a random decimal value.

random.randint(a, b) #

Returns a random whole number from a to b, including both ends.

import random

print(random.randint(1, 6))

Possible output:

4

This is a common choice for dice rolls and number guessing games.

If you want a deeper explanation, see random.randint() explained.

random.randrange(start, stop[, step]) #

Works like range(), but returns one random value from that range.

import random

print(random.randrange(0, 10))
print(random.randrange(0, 10, 2))

Possible output:

7
4

Important detail:

  • random.randrange(0, 10) can return 0 through 9
  • it does not include 10

This is one of the main differences from randint().

random.choice(seq) #

Returns one random item from a sequence such as a list, tuple, or string.

import random

fruits = ["apple", "banana", "cherry"]
print(random.choice(fruits))

Possible output:

banana

It also works with strings:

import random

print(random.choice("python"))

Possible output:

t

For more detail, see random.choice() explained.

random.choices(seq, k=n) #

Returns multiple random items. Values can repeat.

import random

colors = ["red", "blue", "green"]
print(random.choices(colors, k=5))

Possible output:

['blue', 'red', 'blue', 'green', 'blue']

Use this when repeats are allowed.

random.sample(seq, k=n) #

Returns multiple unique random items.

import random

numbers = [1, 2, 3, 4, 5]
print(random.sample(numbers, k=3))

Possible output:

[5, 2, 1]

Use this when you want random items with no duplicates.

random.shuffle(x) #

Shuffles a list in place.

import random

data = [1, 2, 3, 4, 5]
random.shuffle(data)
print(data)

Possible output:

[3, 5, 1, 4, 2]

Important: shuffle() changes the original list. It does not create a new one.

For more detail, see random.shuffle() explained.

Important beginner rules #

Keep these rules in mind when using random:

  • Always import the module first with import random
  • Use choice() only with a non-empty sequence
  • shuffle() changes the original list
  • sample() cannot choose more unique items than the sequence contains
  • randint() includes both the start and end values

Here is a simple example that combines several functions:

import random

names = ["Ana", "Ben", "Cara", "Drew"]

print("Random name:", random.choice(names))
print("Random number:", random.randint(1, 10))
print("Two unique names:", random.sample(names, k=2))

random.shuffle(names)
print("Shuffled list:", names)

Pseudo-random vs truly random #

The random module produces values that look random, but they come from a mathematical process.

For most beginner programs, that is completely fine.

Use random for:

  • games
  • practice projects
  • simulations
  • random test data

Use the secrets module instead for:

  • passwords
  • reset links
  • access tokens
  • security codes

Common problems and confusion #

Here are some common mistakes beginners make with random.

Forgetting to import random #

If you use random.randint() without importing the module first, you will get a NameError.

print(random.randint(1, 10))

Fix it by adding:

import random

If needed, read how to fix NameError: name is not defined.

Using choice() with an empty list #

This causes an error because there is nothing to choose.

import random

items = []
print(random.choice(items))

Make sure the sequence is not empty before calling choice().

import random

items = ["apple", "banana"]

if items:
    print(random.choice(items))

Expecting shuffle() to return a new list #

This is a very common mistake:

import random

my_list = [1, 2, 3]
result = random.shuffle(my_list)
print(result)

Output:

None

Why? Because shuffle() changes the original list directly.

Correct version:

import random

my_list = [1, 2, 3]
random.shuffle(my_list)
print(my_list)

Mixing up randint() and randrange() #

These two functions are similar, but they do not behave exactly the same.

import random

print(random.randint(1, 10))   # can return 10
print(random.randrange(1, 10)) # cannot return 10

This difference can cause off-by-one mistakes.

Common mistakes #

These are some beginner mistakes to watch for:

  • Using random.choice() with an empty list
  • Writing random(1, 10) instead of random.randint(1, 10)
  • Assigning result = random.shuffle(my_list) and expecting a shuffled list back
  • Using random for passwords or secure tokens
  • Forgetting that randint() includes the end value

If you work with lists a lot, it helps to understand how they behave first. See Python lists explained for beginners.

Useful test commands #

You can quickly test the module from the command line:

python --version
python -c "import random; print(random.randint(1, 10))"
python -c "import random; data=[1,2,3]; random.shuffle(data); print(data)"
python -c "import random; print(random.choice(['a','b','c']))"

FAQ #

Do I need to install the random module? #

No. random is part of Python’s standard library.

What is the difference between randint() and randrange()? #

randint(a, b) includes both ends.

randrange() works more like range() and usually excludes the stop value.

Why does shuffle() return None? #

Because it changes the original list directly instead of creating a new one.

Can random.choice() work with strings? #

Yes. A string is a sequence, so choice() can return one random character.

Should I use random for passwords? #

No. Use the secrets module for security-related values.

See also #

Next, read a focused function page like random.randint() or random.choice(), then try a small beginner project such as a number guessing game.

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