Sorting with a Key in Python

Sorting is a fundamental operation in computer science, and Python provides powerful tools for it. This challenge focuses on using the sorted() function and the sort() method with a key argument to sort lists based on a custom criterion, allowing for flexible and efficient data organization. This is crucial for tasks like sorting objects by a specific attribute or strings based on their length.

Problem Description

You are tasked with writing a function that sorts a list of dictionaries based on a specified key within each dictionary. The function should accept a list of dictionaries and a key name as input. It should then return a new list containing the dictionaries sorted in ascending order based on the values associated with the provided key. If a dictionary does not contain the specified key, it should be placed at the end of the sorted list.

Key Requirements:

• The function must use either the sorted() function or the list.sort() method with a key argument.
• The sorting must be done in ascending order.
• Dictionaries without the specified key should be placed at the end of the sorted list.
• The original list should not be modified (if using sorted()). If using list.sort(), the original list is modified.
• The function should handle cases where the key values are of different data types (e.g., strings and numbers) gracefully. Python's default comparison rules should apply.

Expected Behavior:

The function should return a new sorted list of dictionaries (or modify the original list if using list.sort()). The dictionaries should be ordered based on the values associated with the provided key. Dictionaries lacking the key should appear at the end.

Examples

Example 1:

Input: [{'name': 'Alice', 'age': 30}, {'name': 'Bob', 'age': 25}, {'name': 'Charlie'}]
Key: 'age'
Output: [{'name': 'Bob', 'age': 25}, {'name': 'Alice', 'age': 30}, {'name': 'Charlie'}]
Explanation: The dictionaries are sorted by the 'age' key in ascending order. 'Charlie' is placed at the end because it doesn't have an 'age' key.

Example 2:

Input: [{'city': 'New York', 'population': 8419000}, {'city': 'Los Angeles', 'population': 3971000}, {'city': 'Chicago'}]
Key: 'population'
Output: [{'city': 'Los Angeles', 'population': 3971000}, {'city': 'New York', 'population': 8419000}, {'city': 'Chicago'}]
Explanation: The dictionaries are sorted by the 'population' key in ascending order. 'Chicago' is placed at the end because it doesn't have a 'population' key.

Example 3: (Edge Case - Empty List)

Input: []
Key: 'any_key'
Output: []
Explanation: An empty list remains empty after sorting.

Constraints

• The input list will contain only dictionaries.
• The key name will be a string.
• The dictionaries may or may not contain the specified key.
• The number of dictionaries in the list can range from 0 to 1000.
• The key values can be of any comparable data type (e.g., integers, strings, floats).
• Performance: The solution should have a time complexity of O(n log n), where n is the number of dictionaries in the list.

Notes

Consider using a lambda function as the key argument to sorted() or sort(). The key function should return the value to be used for sorting. Handle the case where a dictionary doesn't have the key by returning a default value that ensures it's placed at the end (e.g., float('inf') for numerical sorting or an empty string for string sorting). Remember that sorted() returns a new list, while list.sort() modifies the list in place. Choose the appropriate method based on the problem requirements.