Data Structure

Organizing, managing, and storing data is important as it enables easier access and efficient modification. Data Structures allow you to organize your data in a way that enables you to store the collections of data, relate them, and perform operations on them accordingly.

The basic Python data structures in Python include lists, sets, tuples, and dictionaries. Each of the data structures is unique in its own way.

List

• An ordered collection of items
• Used to store multiple items in a single variable
• A list can be nested, which means that it can contain any type of object.
• List is mutable, which means it can be altered even after being created.

Creation:

• List can be created by using square brackets

 this_list = ["apple", "banana", "cherry"]
 print(this_list)

• List also can be created using the list() constructor

this_list = list(("apple", "banana", "cherry))
print(this_list)

List Items

• Items are ordered, changeable, and allow duplicate values
• Items are indexed, the first item has index[0], the second item has index[1] and so on.

Access List Items:

• List items are indexed and we can access them by referring to the index number

this_list = ["apple", "banana"]
print(this_list[1]) // display banana

• Negative indexing means starting from the end
• [-1] refers to the last item, -2 refers to the second last item

this_list = ["apple", "banana", "cherry"]
print(this_list[-1]) // display cherry

Range of Indexes

• Specify a range of indexes where to start and where to end the range
• It will return the new list of specified items

this_list = ["apple", "banana", "cherry", "Orange", "Kiwi", "melon", "mango"]
print(this_list[2:5])

Note: This search will start at index 2 (included) and end at index 5 (excluded)

print(this_list[:5]) // starting from index 0 upto index 4
print(this_list[2:]) // starting index 2 to last

Append Items:

• To add an item to the end of the list, use the append() method

this_list = ["Ram", "Shynam", "Hari"]
this_list.append("Gita")
print(this_list)

Insert Items:

• To insert an item at a specified index, use the insert(index, item) method.

this_list = ["apple", "banana", "cherry"]
this_list.insert(1,"orange")
print(this_list)

Update Item:

• To change the value of a specified index, refer to the index number

this_list = ["apple", "banana", "cherry"]
this_list[1] = "orange"

print(this_list) # ["apple", "orange", "cherry"]

Remove Items:

The remove() method removes the specified item.

this_list = ["apple", "banana", "cherry"]
this_list.remove("banana")
print(this_list)

If there are more than one item with the specified value, the remove() method removes the first occurrence.

Remove Specified Index

The pop() method removes the specified index.

Example:

this_list = ["apple", "banana", "cherry"]
this_list.pop(1)
print(this_list)

If you don't specify the index, the pop() method removes the last item.

this_list = ["blueberry", "cherry", "mango"]
this_list.remove()
print(this_list)