Randomly generate an even number

[Truman]

How would you randomly generate an even number x, 0 <= x < 100? Fill out the definition for the function genEven(). Please generate a uniform distribution over the even numbers between 0 and 100 (not including 100).

my try:

import random
def genEven():
    '''
    Returns a random even number x, where 0 <= x < 100
    '''
    # Your code here
    rn = random.choice(range(0, 100, 2)) 
    print(rn)

Error:
70
TypeError: unorderable types: NoneType() < int

What am I doing wrong?

[ichabod801]

I take it you are submitting this to a program that checks if your code works correctly. In that case, I bet you need to return rn, not print it. Without an explicit return statement, your function returns None.

[Truman]

Yes, you're correct.

next task is a bit more difficult:
Write a uniformly distributed stochastic program, stochasticNumber, that returns an even number between 9 and 21.

import random
def stochasticNumber():
    '''
    Stochastically generates and returns a uniformly distributed even number between 9 and 21
    '''
    # Your code here
    return [x for _ in range(9,22) for x in [random.randint(9,22)] if x % 2 

I googled similar solution but it is not accepted. Error is the same as in the first case.

[ichabod801]

I don't understand why you aren't just using the same solution as for the first part. Why the double loop? You also appear to be returning a list, not a number. However, there is a missing ']', is there more missing code there?

[Truman]

I just didn't copy it correctly. In this program, I submitted with ']'. Will follow your suggestion.

[Skaperen]

even_random_number = random_number*2
even_random_number = odd_random_number+1
even_random_number = odd_random_number+another_odd_random_number

[DeaD_EyE]

import random


NUMBERS = list(range(2, 100, 2))  # 2, 4, ... 98


def rnd_even():
    return random.choice(NUMBERS)

even_random_vals = [rnd_even() for _ in range(10)]

With so less numbers, you can prepare a list with even numbers an let random.choice choose values.

PS: If you need guaranteed entropy (encryption), this is the wrong way.

[ankit]

hi dear,
here is my code for your question ,

import random
random.randrange(0,100,2)

[Truman]

Hi Everybody,

Forgot to mention that in this second assignment even number between 9 and 21 should be returned.
The first problem is already solved. :)

and the second one:

import random
def stochasticNumber():
    '''
    Stochastically generates and returns a uniformly distributed even number between 9 and 21
    '''
    # Your code here
    for x in range(14):
        rn = random.choice(range(9, 22))
        if rn % 2 == 0:
            return rn

[Skaperen]

i like random.randrange(10,22,2). it's 2 characters shorter and more concise (eliminates 2 lines ... it can be returned directly). i don't know if that makes it more pythonic, but i would hope so.