Python – Generate Random String of Specific Length

Generate Random String with Python

A random string may be required for a system generated strong password, or such another scenarios.

Using random module of Python programming, you can generate such strings of specified length and specified character groups.

To generate a random string of specific length, follow these steps.

Step 1 – Choose Character Group

Choose the character groups from which you would like to pickup the characters. string class provides following character groups:

  • string.ascii_letters
  • string.ascii_lowercase
  • string.ascii_uppercase
  • string.digits
  • string.hexdigits
  • string.letters
  • string.lowercase
  • string.octdigits
  • string.punctuation
  • string.printable
  • string.uppercase
  • string.whitespace

Step 2 – random.choice()

Use random.choice() function with all the character groups (appended by + operator) passed as argument.

random.choice(string.ascii_uppercase + string.digits)
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random.choice() picks one of the characters from the given string or characters.

Step 3 – Repeat picking the characters

Repeat this for N times, N being the length of the random string to be generated.

random.choice(string.ascii_uppercase + string.digits) for _ in range(N)
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Step 4 – Join Characters

Join all these N characters.

''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(N))
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Example – Generate Random String of Specific Length

Let us implement all the afore mentioned steps to generate a random string of specific length.

import random
import string

def randStr(chars = string.ascii_uppercase + string.digits, N=10):
	return ''.join(random.choice(chars) for _ in range(N))

# default length(=10) random string
print(randStr())
# random string of length 7
print(randStr(N=7)) 
# random string with characters picked from ascii_lowercase
print(randStr(chars=string.ascii_lowercase))
# random string with characters picked from 'abcdef123456'
print(randStr(chars='abcdef123456'))
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4FH2R5SQ9D
8STJX1L
iihvalhdwc
d35bbbfcea