# How to Extract Unique Values from a List in Python

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To extract unique values from a list in Python, you can use several approaches. In this answer, we will cover two popular methods: using the `set` function and using list comprehension.

### Method 1: Using the set() function

One simple and efficient way to extract unique values from a list is by using the `set()` function. The `set()` function takes an iterable (such as a list) as input and returns a new set that contains only unique elements. Here’s an example:

```my_list = [1, 2, 2, 3, 4, 4, 5]
unique_values = set(my_list)
print(unique_values)
```

Output:

```{1, 2, 3, 4, 5}
```

In this example, the `set()` function is called with `my_list` as the input, and the returned set is stored in the `unique_values` variable. The `print()` function is then used to display the unique values.

Using the `set()` function is a straightforward and concise method to extract unique values from a list. However, it is important to note that the order of the elements may not be preserved since sets are an unordered collection of unique elements.

Related Article: How To Convert a Dictionary To JSON In Python

### Method 2: Using list comprehension

Another approach to extract unique values from a list is by using list comprehension. List comprehension provides a concise and readable way to create a new list based on an existing list. Here’s an example:

```my_list = [1, 2, 2, 3, 4, 4, 5]
unique_values = [x for x in my_list if my_list.count(x) == 1]
print(unique_values)
```

Output:

```[1, 3, 5]
```

In this example, a list comprehension is used to iterate over each element `x` in `my_list`. The `if` condition `my_list.count(x) == 1` checks if the count of `x` in `my_list` is equal to 1, indicating that it is a unique value. Only the unique values are added to the `unique_values` list.

Using list comprehension allows for more flexibility in filtering the unique values. For example, you can modify the `if` condition to extract unique values based on specific criteria.

### Comparison between the methods

Both methods described above are valid ways to extract unique values from a list in Python. However, there are some differences to consider when choosing between them.

– The `set()` function approach is generally faster and more concise for simple cases where the order of elements doesn’t matter. It automatically removes duplicate values and returns a set, which is an unordered collection of unique elements.
– The list comprehension approach offers more flexibility and control over the filtering of unique values. It allows you to define custom conditions and preserve the order of elements in the original list. However, it may be slower for large lists due to the repeated use of the `count()` function.

It is important to choose the method that best suits your specific use case, taking into account factors such as performance requirements, order preservation, and the complexity of filtering conditions.

Related Article: How to Sort a Dictionary by Key in Python