Question

This is related to random sampling. I am using random.sample(number,5) to return a list of random numbers from within a range of numbers contained in numbers. I am using while i < 100 to return one hundred sets of five numbers. To check for duplicates, I am using :

if len(numbers) != len(set(numbers)):

to identify sets with duplicates and following this with random.sample(number,5) to try to do another randomisation to replace the set with duplicates. I seem to get about 8% getting re-randomised ( using a print statement to say which number was duplicated), but about 5% seem to be missed. What am I doing incorrectly? The actual code is as follows:

while i < 100:
    set1 = random.sample(numbers1,5)
if len(set1) != len(set(set1))
    print('duplicate(s) found, random selection repeated')
set1 = random.sample(numbers1,5)

In another routine I am trying to do the same as above, but searching for duplicates in two sets by adding the same, substituting set2 for set1. This gives the same sorts of failures. The set2 routine is indented and placed immediately below the above routine. While i < 100: is not repeated for set2.
I hope that I have explained my problem clearly!!

Answer 1

There is nothing in your code to stop the second sample from having duplicates. What if you did something like a second while loop?

while i<100:
    i+=1
    set1 = random.sample(numbers1,5)
    while len(set1) != len(set(set1)):
        print('duplicate(s) found, random selection repeated')
        set1 = random.sample(numbers1,5)

Of course you’re still missing the part of the code that does something… beyond the above it’s difficult to tell what you might need to change without a full code sample.

EDIT: here is a working version of the code sample from the comments:

def choose_random(list1,n):
    import random 
    i = 0 
    set_list=[]
    major_numbers=range(1,50) + list1
    print(major_numbers) 
    while i <n: 
        set1 =random.sample(major_numbers,5) 
        set2 =random.sample(major_numbers,2) 
        while len(set(set1)) != len(set1):
            print("Duplicate found at %i"%i)
            print set1
            print("Changing to:")
            set1 =random.sample(major_numbers,5) 
            print set1
        set_list.append([set1,set2])
        i +=1
    return set_list