Write a program (function!) that takes a list and returns a …

Write a program (function!) that takes a list and returns a new list that contains all the elements of the first list minus all the duplicates. Extras: Write two different functions to do this – one using a loop and constructing a list, and another using sets.

Answer

In order to write a program that removes duplicates from a list and returns a new list, we can implement two different approaches: one using a loop and constructing a new list, and another using sets. Both methods have their advantages and disadvantages, and I will explain each approach in detail below.

Approach 1: Using a loop and constructing a new list
To implement this method, we can iterate over the original list and construct a new list by appending each unique element to it. We need to keep track of elements that have already been added to the new list.

Let’s define a function, let’s say `remove_duplicates_loop(list1)`, to implement this approach. The function can look like the following:

“`python
def remove_duplicates_loop(list1):
unique_list = [] # Create an empty list to store unique elements
for element in list1:
if element not in unique_list:
unique_list.append(element)
return unique_list
“`

This function takes a list as input and initializes an empty list called `unique_list`. Then, using a loop, it iterates over the elements in the original list. If an element is not already present in the `unique_list`, it is appended to the list. Finally, the function returns the `unique_list` as the output.

Approach 2: Using sets
Another approach to remove duplicates from a list is by utilizing the unique property of sets. Sets are unordered collections of unique elements, so converting a list to a set will automatically eliminate any duplicates.

Let’s define another function, `remove_duplicates_set(list1)`, to implement this approach:

“`python
def remove_duplicates_set(list1):
unique_list = list(set(list1))
return unique_list
“`

In this function, we first convert the input list into a set using the `set()` function. Then, we convert it back to a list using the `list()` function, which ensures the original order of the elements is preserved. Finally, the function returns the `unique_list` as the output.

Comparing the two approaches, the first method is more suitable when the order of the elements needs to be maintained, as it constructs a new list in the original order. However, it has a higher time complexity of O(n^2) as it checks for duplicate elements for each element in the list. On the other hand, the second method using sets has a time complexity of O(n) as it relies on the unique property of sets. However, it does not preserve the original order of the elements.

In conclusion, we have discussed two different methods to remove duplicates from a list. The first method constructs a new list using a loop, while the second method utilizes sets. The choice between the two approaches depends on the requirements of preserving the order and minimizing the time complexity.