List
Lists are used to store multiple items in a single variable. List name should be in a plural form.
Example :
students = ['Aachal','Aarav','Avinash','Dolly','Deva']
print(students)
Output :
['Aachal', 'Aarav', 'Avinash', 'Dolly', 'Deva']
Slicing on list​
Slice object is used to specify how to slice a list.
Syntax :
stringname[startindex:endindex]
Example :
students = ['Aachal','Aarav','Avinash','Dolly','Deva']
print(students[0:4])
Output :
['Aarav', 'Avinash', 'Dolly']
Example :
students = ['Aachal','Aarav','Avinash','Dolly','Deva']
print(students[4:])
Output :
['Deva']
Example :
students = ['Aachal','Aarav','Avinash','Dolly','Deva']
print(students[-2])
Output :
Dolly
Properties Of List​
1. Ordered​
Lists are in ordered form, which means that the items have a defined order and that order will not change.
Example :
students = ['Aachal','Aarav','Avinash','Dolly','Deva']
print(students)
Output :
['Aachal', 'Aarav', 'Avinash', 'Dolly', 'Deva']
2. Allow duplicates​
Lists can have items with the same value. Lists can contain duplicate values.
Example :
fruits =['apple','banana','cherry','apple','banana']
print(fruits)
Output :
['apple', 'banana', 'cherry', 'apple', 'banana']
3. List can contain different datatype​
You can add differnent datatypes in single list.
Example :
randomData = ["abc",10,True,50.50,"Hii"]
print(randomData)
Output :
['abc', 10, True, 50.5, 'Hii']
4. Changeable​
The list is changeable and we can change add and remove items in a list after it has been created.
Update​
Update (change) a list element at the specified index.
Syntax :
listName[index] = "updated-element"
Example :
courses = ["c","c++","python","javascript","icp"]
print("Befor update: ",courses)
courses[1] = "c++ programming"
print("After update :",courses)
Output :
Befor update: ['c', 'c++', 'python', 'javascript', 'icp']
After update : ['c', 'c++ programming', 'python', 'javascript', 'icp']
Insert​
The insert() method insert an element at the specified position in the list.
Syntax :
listName.insert(index-position, "new-element-to-insert")
Example :
courses = ["c","c++","python","java","icp"]
print("before insert:", courses)
courses.insert(4,"Android Dev")
print("After insert :",courses)
Output :
Before insert: ['c', 'c++', 'python', 'java', 'icp']
After insert : ['c', 'c++', 'python', 'java', 'Android Dev', 'icp']
Append​
The append() method adds an element to the end of the list.
Syntax :
listName.append("element")
Example :
courses = ["c","c++","python","java","icp"]
print("Before append :",courses)
courses.append("Android Dev")
print("After append :",courses)
Output :
Before append : ['c', 'c++', 'python', 'java', 'icp']
After append : ['c', 'c++', 'python', 'java', 'icp', 'Android Dev']
Remove​
The remove() method removes the specified item in the lists.
Syntax :
listName.remove("element")
Example :
fruits = ['appple','banana','orange','cherry']
print("Before remove",fruits)
fruits.remove('banana')
print("After remove",fruits)
Output :
Before remove ['appple', 'banana', 'orange', 'cherry']
After remove ['appple', 'orange', 'cherry']
Pop​
The pop() method remove the element. It takes a single argument (index).
Syntax :
listName.pop(index)
Example :
fruits = ['appple','banana','orange','cherry']
print("Before pop",fruits)
fruits.pop(2)
print("After pop",fruits)
Output :
Before pop ['appple', 'banana', 'orange', 'cherry']
After pop ['appple', 'banana', 'cherry']
Delete​
The delete() method delete elements from the specified index.
Syntax :
del listname[index]
Example :
fruits = ["apple","banana","cherry","mango"]
print("Before delete : ",fruits)
del fruits[1]
print("After delete :",fruits)
Output :
Before delete : ['apple', 'banana', 'cherry', 'mango']
After delete : ['apple', 'cherry', 'mango']
Clear​
The clear() method removes all the elements from the list.
Syntax :
listName.clear()
Example :
fruits = ["apple","banana","cherry","mango"]
print("Before clear :",fruits)
fruits.clear()
print("After clear : ",fruits)
Output :
Before clear : ['apple', 'banana', 'cherry', 'mango']
After clear : []
Sort​
In Python, the sort() method is used to sort a list in-place, meaning it modifies the original list directly. It arranges the elements of the list in either ascending or descending order, depending on the arguments provided.
In the given example, we have a list called alphabets with the values ['A','Z','C','V','P','R']. We will perform sorting on this list.
Ascending Order​
To sort the list in ascending order, we simply call the sort() method on the list without passing any arguments or by passing reverse=False explicitly. Here's the
alphabets = ['A','Z','C','V','P','R']
alphabets.sort()
print(alphabets)
The sort() method rearranges the elements of the alphabets list in ascending order. The output will be:
['A', 'C', 'P', 'R', 'V', 'Z']
Descending Order​
To sort the list in descending order, we pass reverse=True as an argument to the sort() method. Here's the code:
alphabets = ['A','Z','C','V','P','R']
alphabets.sort(reverse=True)
print(alphabets)
The sort() method arranges the elements of the alphabets list in descending order. The output will be:
['Z', 'V', 'R', 'P', 'C', 'A']
In both cases, the sort() method modifies the original list. If you don't want to modify the original list and instead obtain a sorted copy, you can use the sorted() function, which returns a new list with the sorted element.