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Python – Check if elements index are equal for list elements

  • Last Updated : 02 Sep, 2020

Given two lists and check list, test if for each element in check list, elements occur in similar index in 2 lists.

Input : test_list1 = [2, 6, 9, 7, 8], test_list2 = [2, 7, 9, 4, 8], check_list = [9, 8, 7]
Output : False
Explanation : 7 is at 4th and 2nd place in both list, hence False.

Input : test_list1 = [2, 6, 9, 7, 8], test_list2 = [2, 6, 9, 4, 8], check_list = [9, 8, 6]
Output : True
Explanation : All from checklist at similar index, hence True.

Method #1 : Using loop 

In this, we iterate for all the elements in list, if elements are different and is present in check list, then False is returned.

Python3




# Python3 code to demonstrate working of 
# Check if elements index are equal for list elements
# Using loop
  
# initializing lists
test_list1 = [2, 6, 9, 7, 8]
test_list2 = [2, 7, 9, 4, 8]
  
# printing original lists
print("The original list 1 : " + str(test_list1))
print("The original list 2 : " + str(test_list2))
  
# initializing check_list
check_list = [9, 8, 2]
  
res = True 
for idx, ele in enumerate(test_list1):
      
    # check for indifference and containment
    if test_list1[idx] != test_list2[idx] and ele in check_list:
        res = False 
        break
      
# printing result 
print("Are elements at same index for required instances ?:  " + str(res))
Output
The original list 1 : [2, 6, 9, 7, 8]
The original list 2 : [2, 7, 9, 4, 8]
Are elements at same index for required instances ?:  True

Method #2 : Using zip() + all() + generator expression

In this, we pair like indices using zip() and then all() is used to check for all indices, generator expression is used for iteration logic.

Python3




# Python3 code to demonstrate working of 
# Check if elements index are equal for list elements
# Using zip() + all() + generator expression
  
# initializing lists
test_list1 = [2, 6, 9, 7, 8]
test_list2 = [2, 7, 9, 4, 8]
  
# printing original lists
print("The original list 1 : " + str(test_list1))
print("The original list 2 : " + str(test_list2))
  
# initializing check_list
check_list = [9, 8, 2]
  
# checking for all elements equal in check list using all()
res = all(a == b for a, b in zip(test_list1, test_list2) if a in check_list)
      
# printing result 
print("Are elements at same index for required instances ?:  " + str(res))
Output
The original list 1 : [2, 6, 9, 7, 8]
The original list 2 : [2, 7, 9, 4, 8]
Are elements at same index for required instances ?:  True


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