How to insert an object so that it appears under a certain index in a data structure?

To insert an element at a specific index in a data structure in Python, the following methods are usually used:

List structures (list, collections.deque):

The insert(index, element) method is used.

# Example for list
my_list = [1, 2, 3, 4, 5]
my_list.insert(2, 10)  # Insert 10 at index 2

# Result: [1, 2, 10, 3, 4, 5]

# Example for deque
from collections import deque
my_deque = deque([1, 2, 3, 4, 5])
my_deque.insert(2, 10) # Insert 10 at index 2

# Result: deque([1, 2, 10, 3, 4, 5])

Structures that do not support arbitrary index insertion (set, dict, tuple):

For these structures, which by their nature do not support inserting an element at an arbitrary index in the middle (tuples are immutable, sets are unordered based on hashing, dicts are based on keys), direct "insertion at a specific index" is impossible in the same sense as for lists. Only workaround methods or structure conversions are possible.

• Tuple: Since tuples are immutable, to "insert" an element, you need to create a new tuple by concatenating parts of the original and the new element.

  my_tuple = (1, 2, 3, 4, 5)
  index_to_insert = 2
  element_to_insert = 10
  
  new_tuple = my_tuple[:index_to_insert] + (element_to_insert,) + my_tuple[index_to_insert:]
  
  # Result: (1, 2, 10, 3, 4, 5)
  

• Set: Sets are unordered, so the concept of "index" does not exist. You can add an element using add(), but its position in the actual data storage cannot be determined.

  my_set = {1, 2, 3, 4, 5}
  element_to_add = 10
  my_set.add(element_to_add)
  
  # Result: {1, 2, 3, 4, 5, 10} (order may vary)
  

• Dict: Dictionaries are based on key-value pairs. You cannot "insert" an element by index in terms of element order. You can only add or update elements by their key. In Python 3.7+, the insertion order of keys is preserved, but this is not equivalent to arbitrary insertion by numerical index.

  my_dict = {'a': 1, 'b': 2, 'c': 3}
  # Cannot "insert" an element by numerical index
  

The method chosen depends on the data structure type and the required functionality. For mutable sequential structures (lists, deque), the insert() method is the standard and efficient way. For other structures, different approaches are needed, consistent with their internal design.