In this post, we will learn how to slice a list in Python with examples. By using indexing, we can select/change/delete a single element. But Sometimes we have to select/change/modify/delete a range of elements from the python list then slicing is used. The slicing is represented By using a colon(:) also known as a slicing operator. The syntax to use the slicing operator
Syntax
The: slicing operator is used to do slicing in Python. It returns the new list of elements that pass the given slicing range from the existing list.
list[start:stop: step]
#some mostly used slining syntax
list[start:stop] # slicing start from start index and stop-1
list[start:] # get item from start to stop
list[:stop] # get items from the start to stop-1
list[:] # get all element in a list
- start: The index of the list at where to start the slicing.
- stop: The index at slicing will stop.
- step: Select nth element within start and stop range.
Program Examples of Below Syntax
pre_List = ['at','on','into','up','The',2,5,6]
#here the syntax : list[start:stop]
print(pre_List[1:3])
#here the syntax : list[start:]
print(pre_List[1:])
#here the syntax : list[:stop]
print(pre_List[:5])
#here the syntax : list[:]
print(pre_List[:])
Output
['on', 'into']
['on', 'into', 'up', 'The', 2, 5, 6]
['at', 'on', 'into', 'up', 'The']
['at', 'on', 'into', 'up', 'The', 2, 5, 6]
1. How to slice a list in Python from start to end range
In this example, we are slicing the list starting from index 1 and stopping at index 6. The element at index 6 will not be included in the resulting output.
pre_List = ['at','on','into','up','The',2,5,6]
#start from index 1 to end at 6, element at index 6 (will not be included)
print(pre_List[1:6])
Output
['on', 'into', 'up', 'The', 2]
2. How to slice a list in Python a start index to end
In this example, we are accessing the whole list by using the slicing operator [:] that will return a copy of the whole list. The pre_List[1:] slicing of the list element starts from index 1 to the end of the list.
pre_List = ['at','on','into','up','The',2,5,6]
#start from index 0 to end at end of list or whole list
print('whole list :',pre_List[:])
#start from index 1 to end at end of list the element at end index will not included
print('start from index 1 to end:',pre_List[1:])
Output
whole list : ['at', 'on', 'into', 'up', 'The', 2, 5, 6]
start from index 1 to end: ['on', 'into', 'up', 'The', 2, 5, 6]
3. How to slice a list in Python before some index using slicing
In this example, we are accessing an element starting from index 0 to index 4. The element at index 4 will not be included in output result
pre_List = ['at','on','into','up','The',2,5,6]
#start from index 0 to index 4
print('Access element before some index :',pre_List[:4])
Output
Access element before some index : ['at', 'on', 'into', 'up']
4. Access list elements between some intervals using Slicing
In this example, we are accessing the list elements by using start, stop and step. The slicing starts at index 0 and increments by 1 every step and stops at index 5.
pre_List = ['at','on','into','up','The',2,5,6]
print('slicing list using stat,stop,step:',pre_List[1:5:1])
Output
slicing list using stat,stop,step: ['on', 'into', 'up', 'The']
5. Access list element using negative slicing end to start
In this example, we will understand how to access the list element by using negative slicing using code pre_List[:-1] that will slice the list starting from index 0 to the end of the list.
pre_List = ['at','on','into','up','The',2,5,6]
print('slicing list using negative index:',pre_List[:-1])
Output
slicing list using negative index: ['at', 'on', 'into', 'up', 'The', 2, 5]
6. Access list element using a range of negative slicing
In this example, we are accessing a range of list elements using negative indexing starting from index -1 to stop at index -5. To access all list elements by negative index, we have to use pre_List[-6:]. Let us understand with the below example
pre_List = ['at','on','into','up','The',2,5,6]
print('slicing list using negative index:',pre_List[-6:])
print('slicing list using negative index:',pre_List[-5:-1])
Output
slicing list using negative index: ['into', 'up', 'The', 2, 5, 6]
slicing list using negative index: ['up', 'The', 2, 5]
7. Access list elements negative and positive slicing
In this example, we are accessing the list element by using positive and negative slicing by using code pre_List[1:-5]
pre_List = ['at','on','into','up','The',2,5,6]
print('slicing list using negativ and postive index:',pre_List[1:-5])
Output
slicing list using negativ and postive index: ['on', 'into']