Python output random lists from input list

Question

I need to create 3 lists from my list1. One with 70% of the values and two with 20% and 10%.

list1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

# listOutput70 = select  70% of list1 items(randomly)
# with the remaining create two lists of 20% and 10%

#the output can be something like:

#listOutput70 = [2,7,9,8,4,10,3]
#listOutput20 = [1,5]
#listOutput10 = [6]

I already have some code to generate a percentage output, but works only for one list.

import random


def selector():

    RandomSelection = []
    mySel = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    PercentEnter= 70
    
    New_sel_nb = len(mySel)*int(PercentEnter)/100
        
    
    while len(RandomSelection) < New_sel_nb:
        randomNumber = random.randrange(0, len(mySel),1)
    
        RandomSelection.append(mySel[randomNumber])
    
        RandomSelection = list(set(RandomSelection))
        
    print(RandomSelection)


selector()
#[2, 3, 6, 7, 8, 9, 10]

it is unclear what you want, because the code you have seems to work as it is, do you want to make a random partitioning of the list into lists of length 1, 2, and 7? — L.Grozinger
– L.Grozinger, Commented Jul 7, 2022 at 20:47
@L.Grozinger, I needed it to be in percentage so I can change them later if needed. basically output 3 lists, one with 70% of the values, another one with 20% and the last one with 10%. The code I have only works for one list. Then if I run the function again it will select some of the same elements. — johancc
– johancc, Commented Jul 7, 2022 at 20:51

Barmar · Accepted Answer · 2022-07-07 20:55:48Z

3

Shuffle the list with random.shuffle(). Then use slices to get each percentage.

def selector(percents):
    RandomSelection = []
    mySel = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    random.shuffle(mySel)
    
    start = 0
    for cur in percents:
        end = start + cur * len(mySel) // 100
        RandomSelection.append(mySel[start:end])
        start = end

    return RandomSelection

print(selector([70, 20, 10]))

edited Jul 7, 2022 at 20:55

answered Jul 7, 2022 at 20:49

Barmar

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3 Comments

johancc Over a year ago

Thanks, but I am getting an error: # SyntaxError: unexpected EOF while parsing #

Barmar Over a year ago

Sorry, missing ) at the end.

Barmar Over a year ago

@DanielHao If you do that, you need to remove the choices from the list between each iteration.

chubercik · Accepted Answer · 2022-07-07 22:54:43Z

1

Using numpy.split function:

from random import shuffle
from numpy import split as np_split


def selector(og_list, percentages):
    if sum(percentages) != 100:
        raise ValueError("Percentages must sum to 100!")
    percentages.sort()
    splits = [round(len(og_list) * percentages[0] / 100),
              round(len(og_list) * (percentages[0] + percentages[1]) / 100)]
    shuffle(og_list)
    return [list(subset) for subset in np_split(og_list, splits)]

Usage:

my_list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

my_percentages_1 = [10, 20, 70]
my_percentages_2 = [40, 10, 50]
my_percentages_3 = [63, 31, 6]

result_1 = selector(my_list, my_percentages_1)
result_2 = selector(my_list, my_percentages_2)
result_3 = selector(my_list, my_percentages_3)

print(result_1)
print(result_2)
print(result_3)

[[2], [8, 3], [4, 9, 7, 5, 0, 1, 6]]
[[8], [0, 2, 7, 1], [9, 4, 6, 3, 5]]
[[1], [0, 3, 2], [4, 8, 5, 9, 7, 6]]

edited Jul 7, 2022 at 22:54

answered Jul 7, 2022 at 20:56

chubercik

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3 Comments

Barmar Over a year ago

The question is about splitting the list into multiple segments: 70%, 20%, 10%. Your code only works for one, just like the OP's code.

johancc Over a year ago

Thanks, but this only outputs one list, I need 3. One with 70%, and with the remaining items one with 20% and another with 10.

chubercik Over a year ago

Oh, let me edit my code to comply with OP's needs and I'll update it right away.

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