Meaning of data structure:
Data structure is Organizing, managing and storing data is important as it enables easier access and efficient modifications. Data Structures allows you to organize your data in such a way that enables you to store collections of data.
Types of Data Structures in Python:
Python has implicit support for Data Structures which enable you to store and access data.
*These structures are called List, Dictionary, Tuple and Set.
python allows its users to create their own Data Structures enabling them to have full control over their functionality. The most prominent Data Structures are Stack, Queue, Tree, Linked List and so on which are also available to you in other programming languages.
Built-in Data Structures:
These Data Structures are built-in with Python which makes programming easier and helps programmers use them to obtain solutions faster.
Lists:
Lists are used to store data of different data types in a sequential manner. There are addresses assigned to every element of the list, which is called as Index. The index value starts from 0 and goes on until the last element called the positive index. negative indexing which starts from -1 enabling you to access elements from the last to first.
Creating a list:
To create a list, you use the square brackets and add elements into it accordingly. If you do not pass any elements inside the square brackets, you get an empty list as the output.
my_list = [] #create empty list
print(my_list)
my_list = [1, 2, 3, 'example', 3.132] #creating list with data
print(my_list)
Output:
[]
[1, 2, 3, ‘example’, 3.132]
Adding Elements:
Adding the elements in the list can be achieved using the append(), extend() and insert() functions.
*The append() function adds all the elements passed to it as a single element.
*The extend() function adds the elements one-by-one into the list.
*The insert() function adds the element passed to the index value and increase the size of the list too.
my_list = [1, 2, 3]
print(my_list)
my_list.append([555, 12]) #add as a single element
print(my_list)
my_list.extend([234, 'more_example']) #add as different elements
print(my_list)
my_list.insert(1, 'insert_example') #add element i
print(my_list)
Output:
[1, 2, 3]
[1, 2, 3, [555, 12]]
[1, 2, 3, [555, 12], 234, ‘more_example’]
[1, ‘insert_example’, 2, 3, [555, 12], 234, ‘more_example’]
Deleting Elements:
*To delete elements, use the del keyword which is built-in into Python but this does not return anything back to us.
*If you want the element back, you use the pop() function which takes the index value.
*To remove an element by its value, you use the remove() function.
my_list = [1, 2, 3, 'example', 3.132, 10, 30]
del my_list[5] #delete element at index 5
print(my_list)
my_list.remove('example') #remove element with value
print(my_list)
a = my_list.pop(1) #pop element from list
print('Popped Element: ', a, ' List remaining: ', my_list)
my_list.clear() #empty the list
print(my_list)
output:
[1, 2, 3, ‘example’, 3.132, 30]
[1, 2, 3, 3.132, 30]
Popped Element: 2 List remaining: [1, 3, 3.132, 30]
[]
Accessing Elements:
Accessing elements is the same as accessing Strings in Python. You pass the index values and hence can obtain the values as needed.
my_list = [1, 2, 3, 'example', 3.132, 10, 30]
for element in my_list: #access elements one by one
print(element)
print(my_list) #access all elements
print(my_list[3]) #access index 3 element
print(my_list[0:2]) #access elements from 0 to 1 and exclude 2
print(my_list[::-1]) #access elements in reverse
Output:
example
3.132
10
30
[1, 2, 3, ‘example’, 3.132, 10, 30]
example
[1, 2]
[30, 10, 3.132, ‘example’, 3, 2, 1]
Other Functions:
You have several other functions that can be used when working with lists.
*The len() function returns to us the length of the list.
*The index() function finds the index value of value passed where it has been encountered the first time.
*The count() function finds the count of the value passed to it.
*The sorted() and sort() functions do the same thing, that is to sort the values of the list. The sorted() has a return type whereas the sort() modifies the original list.
my_list = [1, 2, 3, 10, 30, 10]
print(len(my_list)) #find length of list
print(my_list.index(10)) #find index of element that occurs first
print(my_list.count(10)) #find count of the element
print(sorted(my_list)) #print sorted list but not change original
my_list.sort(reverse=True) #sort original list
print(my_list)
Output:
6
3
2
[1, 2, 3, 10, 10, 30]
[30, 10, 10, 3, 2, 1]
