# Get unique values from a list in Python

A list in python is a number of items placed with in [] which may or may not have same data types. It can also contain duplicates. In this article we will see how to extract only the unique values from a list.

## With append()

In this approach we will first create a new empty list and then keep appending elements to this new list only if it is not already present in this new list. A for loop is used along with not in condition. It checks for the existence of the incoming element and it is appended only if it is not already present.

## Example

Live Demo

def catch_unique(list_in):
# intilize an empty list
unq_list = []

# Check for elements
for x in list_in:
# check if exists in unq_list
if x not in unq_list:
unq_list.append(x)
# print list
for x in unq_list:
print(x)

Alist = ['Mon', 'Tue', 'Mon', 'wed', 40, 40]
print("Unique values from the list is")
catch_unique(Alist)

## Output

Running the above code gives us the following result −

Unique values from the list is
Mon
Tue
wed
40

## With Set

A set only contains unique values. In this approach we convert the list to a set and then convert the set back to a list which holds all the unique elements.

## Example

Live Demo

Alist = ['Mon', 'Tue', 'Mon', 'wed', 40, 40]
A_set = set(Alist)
New_List=list(A_set)
print("Unique values from the list is")
print(New_List)

## Output

Running the above code gives us the following result −

Unique values from the list is
[40, 'Tue', 'wed', 'Mon']

## Using numpy

The numpy library has a function named unique which does the straight job of taking the list as input and giving the unique elements as a new list.

## Example

Live Demo

import numpy as np

Alist = ['Mon', 'Tue', 'Mon', 'wed', 40, 40]
print("The unique values from list is: ")
print(np.unique(Alist))

## Output

Running the above code gives us the following result −

The unique values from list is:
['40' 'Mon' 'Tue' 'wed']

Updated on: 09-Sep-2020

3K+ Views