Find missing elements in List in Python

PythonServer Side ProgrammingProgramming

If we have a list containing numbers, we can check if the numbers are contiguous or not and also find which numbers are missing from a range of numbers considering the highest number as the final value.

With range and max

We can design a for loop to check for absence of values in a range using the not in operator. Then capture all these values by adding them to a new list which becomes the result set.

Example

 Live Demo

listA = [1,5,6, 7,11,14]

# Original list
print("Given list : ",listA)

# using range and max
res = [ele for ele in range(max(listA) + 1) if ele not in listA]

# Result
print("Missing elements from the list : \n" ,res)

Output

Running the above code gives us the following result −

Given list : [1, 5, 6, 7, 11, 14]
Missing elements from the list :
[0, 2, 3, 4, 8, 9, 10, 12, 13]

with set

We apply the set function to hold all the unique values for a given range and then subtracting the given list from it. So this gives the result set containing the missing values from the contiguous numbers.

Example

 Live Demo

listA = [1,5,6, 7,11,14]

# printing original list
print("Given list : ",listA)

# using set
res = list(set(range(max(listA) + 1)) - set(listA))

# Result
print("Missing elements from the list : \n" ,res)

Output

Running the above code gives us the following result −

Given list : [1, 5, 6, 7, 11, 14]
Missing elements from the list :
[0, 2, 3, 4, 8, 9, 10, 12, 13]
raja
Published on 26-Aug-2020 08:07:52
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