CODEWITHSUNDEEP
python
Jacob Peck
Jacob Peck

Reputation: 11

generating a four digit list without repeats

I'm trying to make a four digit long list, with no repeated digits. However, the code i am running is only generating one digit, and then closing. Can anybody see why?

import random

complist = [0,1,2,3,4,5,6,7,8,9]
compnum = []
userlist = []
usernum = []


def compnumber(compnum):
    for i in range(4):
        compx = random.randint(0,9)
        if compx in compnum:
            compx = 0
            return compx, compnum
        else:
            compnum.append(compx)
            compx = 0
            return compx, compnum
compnumber(compnum)
print(compnum)

thanks!

Upvotes: 0

Views: 99

Answers (4)

vash_the_stampede
vash_the_stampede

Reputation: 4606

import random

complist = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
compnum = []
userlist = []
usernum = []

def compnumber(compnum):
    for i in range(4):
        compx = random.randint(0, 9)
        while compx in compnum:
            compx = random.randint(0, 9)
        compnum.append(compx)

compnumber(compnum)
print(compnum)

You could set a while condition that won't allow the randint to be used if it already has been added to compnum

Output

(xenial)vash@localhost:~/python$ python3.7 helpin.py 
[1, 4, 2, 3]
[4, 2, 1, 8]
[2, 0, 4, 1]
[4, 6, 2, 3]
[1, 2, 0, 9]
[6, 4, 9, 3]
[2, 8, 7, 0]
[7, 5, 4, 0]
[0, 9, 7, 3]
[4, 9, 2, 1]

Results for 10 iterations

I would consider when defining your function to use a different variable name, not the actual variable you are passing, Ex. def compnumber(list_to_append)

Upvotes: 1

Dani Mesejo
Dani Mesejo

Reputation: 61930

There are a few issues with your code:

  1. You are returning inside the for-loop
  2. The loop only runs 4 times, independent of compnum having 4 values, so it might return a compnum with less than 4 values.

You can write it like this:

import random

complist = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
compnum = []
userlist = []
usernum = []


def compnumber(compnum):
    while len(compnum) != 4:
        compx = random.randint(0, 9)
        if compx not in compnum:
            compnum.append(compx)
    return compx, compnum


compnumber(compnum)
print(compnum)

Output

[9, 7, 8, 2] # as an example

But the best way to do it is to use the sample function of random module, like this:

import random

complist = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
compnum = random.sample(complist, 4)

print(compnum)

Upvotes: 0

Zach Valenta
Zach Valenta

Reputation: 1879

The most Pythonic way to do it is Daniel's answer, using sample().

Using loops (your approach) is also fine.

Here's my take on how to do it with a loop:

import random

compnum = []

def compnumber(ur_list):
    while len(ur_list) < 4:
        compx = random.randint(0,9)
        if compx not in ur_list:
            ur_list.append(compx)
    return ur_list

print(compnumber(compnum))

Upvotes: 0

Daniel
Daniel

Reputation: 42778

You have a return in your for-loop, so only one number is generated.

numbers = random.sample(range(10),4)

Upvotes: 3

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