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]
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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 listtest_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 slicingres = Falsefor 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)) |
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 listtest_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 expressionres = 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)) |
The original list : [5, 6, 3, 8, 2, 1, 7, 1] Is sublist present in list ? : True
