Python - Update in Array

The array module provides support for arrays, and understanding how to update elements within these arrays is essential for efficient data manipulation. Updating elements in an array can be done in several ways, including direct assignment, slicing and using built-in methods. Let's explore these methods:

Direct Assignment to Update an Array Element

The simplest way to update an array element is by accessing the element using its index and assigning a new value. This works exactly like updating elements in a list.

# Original array
arr = array.array('i', [1, 2, 3, 4, 5])

# Update the element at index 2 (third element)
arr[2] = 10
print(arr)  

Explanation:

• We accessed the element at index 2 (which is 3) and assigned a new value 10 to it.
• After updating, the array reflects the change and the element at index 2 is now 10.

Using Slicing to Update Multiple Array Elements

You can also update multiple elements in an array using slicing. This method is useful if you want to replace a range of elements in the array.

# Original array
arr = array.array('i', [1, 2, 3, 4, 5])

# Update the elements at indices 1 to 3 (second to fourth elements)
arr[1:4] = array.array('i', [20, 30, 40])
print(arr)  

Explanation:

• We used slicing to select elements from index 1 to 3 ([2, 3, 4]) and replaced them with a new array [20, 30, 40].
• The array is updated to reflect the new values at indices 1 to 3.

Using Built-in Methods to Modify the Array

Python’s array module offers various methods for modifying arrays. Some of the most commonly used methods are:

• append(): Adds a single element to the end of the array.
• extend(): Adds multiple elements to the end of the array.
• insert(): Inserts a new element at a specified position.
• remove(): Removes the first occurrence of a specified value.
• pop(): Removes and returns an element at a given index.

arr = array.array('i', [1, 2, 3])
arr.append(4)
print(arr)  

arr.insert(2, 10)  # Insert 10 at index 2
print(arr)  

arr.remove(3)  # Removes the first occurrence of 3
print(arr)  

val = arr.pop(1)  # Remove and return the element at index 1
print(val)  
print(arr)  

Explanation:

• We added 4 to the end of the array using append().
• We used insert() to add 10 at index 2, shifting the elements after it.
• remove() removes the first occurrence of the value 3 from the array.
• The pop() method removes and returns the element at index 1. In this case, it removes 2 and the array is updated accordingly.