Create new list containing only unique values from original list

Question

I have a function that finds the unique values of a list, but I can't create a new list with them.

import numpy as np
def unique(list): 
    x = np.array(list) 
    print(np.unique(x))

list1 = [10, 20, 10, 30, 40, 40]  
unique(list1)

My output are the unique values but I want to create a new list containing them. I thought it would be as simple as bellow but when I print list2 the output says "None". I feel there is a really easy answer but I can't figure it out.

list2 = unique(list1) 
print(list2)

Your function returns `None` implicitly because you never return anything explicitly — juanpa.arrivillaga, Oct 19 '20 at 23:43
Why do you need `numpy` for this? You can simply do `list1 = list(set(list1))`. — Selcuk, Oct 19 '20 at 23:46
@eloen please accept one of the answers as solution by clicking the checkmark next to the answer. Thank you! — David Erickson, Dec 10 '20 at 05:59

score 1 · Answer 1 · answered Oct 19 '20 at 23:46

1

The result of the function must be returned.

Try this:

import numpy as np
def unique(list):
    x = np.array(list)
    x = np.unique(x)
    return x

list1 = [10, 20, 10, 30, 40, 40]
new_list = unique(list1)
print(new_list)

answered Oct 19 '20 at 23:46

Higs

384
2
7

Thanks, this was exactly what I looked for – eloen Oct 19 '20 at 23:53
You're welcome @eloen – Higs Oct 19 '20 at 23:55

score 0 · Answer 2 · answered Oct 19 '20 at 23:45

0

If order doesn't matter you can use set to remove dupes and then back to a list:

list1 = [10, 20, 10, 30, 40, 40]
list1 = list(set(list1))
list1
[40, 10, 20, 30]

answered Oct 19 '20 at 23:45

David Erickson

16,433
2
19
35

This doesn't address the OP's problem at all, they already have a method to get unique values anyway, showing them another method doesn't address the fundamental issue of their function not returning anything. If they were asking how to remove duplicates from a list it would be a duplicate anyway – juanpa.arrivillaga Oct 19 '20 at 23:47
1

Thanks this is much simpler and order dosn't matter. – eloen Oct 19 '20 at 23:48

Create new list containing only unique values from original list

2 Answers2