Random

Programs often need some source of random numbers. Think of generating a user name or ID—a random sequence can be helpful.

Random function

For Python developers there is a pseudo-random number generator. We call randint and random.choice. These are built-in, as Python is "batteries included."

With the random module (and randint) we easily generate random numbers. The randint() method receives 2 arguments. They are both inclusive (including the numbers).

import random

i = 0
while i < 10:
    # Get random number in range 0 through 9.
    n = random.randint(0, 9)
    print(n)
    i += 1
7
0  (Min)
9  (Max)
3
4
6
5
4
4
8

Random.choice

In this Python example, we use random.choice() on a list and a tuple. When we execute this program, it gives a different result—unless the random choices are the same.

import random

# Use random.choice on a list.
arr = [1, 5, 9, 100]
n = random.choice(arr)

# Use random.choice on a tuple.
tup = (2, 4, 6)
y = random.choice(tup)

# Display.
print(n, y)
100 4

Random lowercase letter

This program generates a random lowercase char. It only supports the chars A through Z, but it is easily modified.

import random

# This string literal contains all lowercase ASCII letters.
values = "abcdefghijklmnopqrstuvwxyz"

for i in range(0, 10):
    # random.choice returns a random character.
    letter = random.choice(values)
    print(letter)
v
t
j
y
s
l
m
r
a
j

Random phrases

Random.choice can be used to easily create random text or phrases. Here we populate a list with seven words and then add five random choices to a string.

import random

# Create a list of words.
words = []
words.append("hello,")
words.append("cat,")
words.append("food")
words.append("buy")
words.append("free")
words.append("click")
words.append("here")

# Create sentence of five words.
result = ""
for i in range(0, 5):
    result += random.choice(words) + " "

# Fix trailing punctuation and capitalize.
result = result.strip(" ,")
result = result.capitalize()
result += "!"
print(result)
Hello, here cat, buy free!

The randint and random.choice methods are excellent choices for pseudo-random numbers. They are clear. They are easy to remember and need few comments.

One key thing to remember: the randint method receives two arguments that are inclusive. So the highest number is included. This differs from other languages like Java.