Python - Check for Sublist in List

Sometimes, while working with Python Lists, we can have a problem in which we need to check if a particular sublist is contained in exact sequence in a list. This task can have application in many domains such as school programming and web development. Let’s discuss certain ways in which this task can be performed.

Input : test_list = [5, 6, 3, 8, 2, 1, 7, 1], sublist = [8, 2, 3]
Output : False

Input : test_list = [5, 6, 3, 8, 2, 3, 7, 1], sublist = [8, 2, 3]
Output : True

Method #1 : Using loop + list slicing
The combination of above functions can be used to solve this problem. In this, we perform task of checking for sublist by incremental slicing using list slicing technique.

# Python3 code to demonstrate working of  
# Check for Sublist in List 
# Using loop + list slicing 
  
# initializing list 
test_list = [5, 6, 3, 8, 2, 1, 7, 1] 
  
# printing original list  
print("The original list : " + str(test_list)) 
  
# initializing sublist  
sublist = [8, 2, 1] 
  
# Check for Sublist in List 
# Using loop + list slicing 
res = False
for idx in range(len(test_list) - len(sublist) + 1): 
        if test_list[idx : idx + len(sublist)] == sublist: 
            res = True 
            break
          
# printing result  
print("Is sublist present in list ? : " + str(res)) 

Output :

The original list : [5, 6, 3, 8, 2, 1, 7, 1]
Is sublist present in list ? : True

Method #2 : Using any() + list slicing + generator expression
The combination of above functions is used to solve this problem. In this, we perform the task of checking for any sublist equating to desired using any() and list slicing is used to slice incremental list of desired length.

# Python3 code to demonstrate working of  
# Check for Sublist in List 
# Using any() + list slicing + generator expression 
  
# initializing list 
test_list = [5, 6, 3, 8, 2, 1, 7, 1] 
  
# printing original list  
print("The original list : " + str(test_list)) 
  
# initializing sublist  
sublist = [8, 2, 1] 
  
# Check for Sublist in List 
# Using any() + list slicing + generator expression 
res = any(test_list[idx : idx + len(sublist)] == sublist 
        for idx in range(len(test_list) - len(sublist) + 1)) 
          
# printing result  
print("Is sublist present in list ? : " + str(res)) 

Output :

The original list : [5, 6, 3, 8, 2, 1, 7, 1]
Is sublist present in list ? : True

My Personal Notes

Python – Check for Sublist in List

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