Generate Random String Without Duplicates in Python

When we need to create a random string in Python, sometimes we want to make sure that the string does not have any duplicate characters. For example, if we're generating a random password or a unique identifier, we might want to ensure each character appears only once.

Using random.sample()

Using random.sample() is the simplest and most efficient function that allows us to pick a specified number of unique elements from a sequence. It ensures there are no duplicates in the result.

import random
import string
# Generate a random string of 8 unique characters
def generate_random_string(length):
    return ''.join(random.sample(string.ascii_letters, length))
random_string = generate_random_string(8)
print(random_string)

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• string.ascii_letters gives us all the letters in the alphabet (both lowercase and uppercase).
• random.sample() randomly picks length number of unique characters from this list.
• ''.join() combines the selected characters into a single string.

Using random.shuffle()

Another way to generate a random string without duplicates is to shuffle a list of characters and then select the first few elements. This method gives us more control over the randomization process.

import random
import string
# Generate a random string of 8 unique characters
def generate_random_string(length):
    chars = list(string.ascii_letters)
    random.shuffle(chars)  # Shuffle the list of characters
    return ''.join(chars[:length])
random_string = generate_random_string(8)
print(random_string)

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Manually Generating a Random String

If we want to take a more manual approach or need more control over the process, we can create a random string by picking characters one by one while ensuring that each character is unique. This is a bit more complex but useful in some cases.

import random
import string
# Generate a random string of 8 unique characters
def generate_random_string(length):
    chars = string.ascii_letters
    result = []
    
    while len(result) < length:
        char = random.choice(chars)
        if char not in result:
            result.append(char)
    
    return ''.join(result)
random_string = generate_random_string(8)
print(random_string)

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• While this method works, it is less efficient than the first two because we keep checking for duplicates, which can slow things down as the string length increases.