random Numbers
This page was last reviewed on Oct 11, 2023.
Dot Net Perls
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).
Argument 1 The first argument to randint is the inclusive lower value of the range. Randint can return this value.
Argument 2 The second argument to randint is the inclusive upper value of the range. Randint can also return this value.
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.
Detail The random.choice method supports lists and tuples. As we see next, it also chooses a random character from a string.
String List
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.
Tip To generate a random char from any set, you can just change the string literal in this program.
Tip 2 A list could also be used: we could add in a loop (or list comprehension) all the desired letters.
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.
Detail We call strip to remove trailing punctuation and spaces. Capitalize improves the phrase's appearance.
String strip
String lower, upper
Note I encourage you to research Markov chains for better random text generation. This program is not good.
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.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
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