In this tutorial, we will learn how to get all the subsets of a list in Python. This is useful when you want to perform analysis, generate combinations, or find the power set of a list of elements.

We will discuss two methods to achieve this: first, by using a manual approach with loops, and second, by using the built-in itertools.chain and itertools.combinations functions.

### Method 1: Using Loops

The first approach involves using a loop to iterate through the list and generate all possible subsets. By doing this, we will be creating the list of subsets step by step. Here’s a breakdown of the steps:

- Initialize an empty list,
**result**, which will store the subsets. - Add an empty subset to the
**result**list. - Iteratively go through each element in the input list.
- For each element, generate new subsets by adding it to the existing subsets in the
**result**list. - Add these new subsets to the
**result**list.

Now, let’s see the code implementation:

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def get_all_subsets(input_list): result = [[]] for elem in input_list: new_subsets = [subset + [elem] for subset in result] result.extend(new_subsets) return result |

Let’s test this function on an example input list:

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input_list = [1, 2, 3] subsets = get_all_subsets(input_list) print(subsets) |

Output:[[], [1], [2], [1, 2], [3], [1, 3], [2, 3], [1, 2, 3]]

We can see that the function generated all possible subsets, including the empty set and the input list itself.

### Method 2: Using itertools.chain and itertools.combinations

The second approach involves using the built-in Python library itertools to generate the subsets. The main advantage of using itertools is that it is more efficient in terms of both memory usage and computation time.

Here’s a step-by-step breakdown of the process:

- Import
**itertools.chain**and**itertools.combinations**functions. - Initialize an empty list,
**result**, which will store the subsets. - Iterate through the range from 0 to the length of the input list.
- For each number in the range, find all possible combinations using the
**combinations**function. - Add the combinations to the
**result**list using the**chain**function.

Now, let’s see the code implementation:

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from itertools import chain, combinations def get_all_subsets(input_list): result = list(chain.from_iterable(combinations(input_list, r) for r in range(len(input_list) + 1))) return result |

Let’s test this function on an example input list:

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input_list = [1, 2, 3] subsets = get_all_subsets(input_list) print(subsets) |

## Output

[(), (1,), (2,), (3,), (1, 2), (1, 3), (2, 3), (1, 2, 3)]

We can see that the function generated all possible subsets in the form of tuples. We can easily convert them to lists if needed.

## Conclusion

In this tutorial, we covered two methods to get all the subsets of a list in Python. The first approach was a manual implementation using loops. The second approach made use of the built-in itertools library to generate combinations more efficiently. Both methods have their merits and can be used based on your requirements and situation.