Access Kth Element in Set Without Deletion in Python

In Python, a set is an unordered collection of unique elements, represented by {}. It allows efficient membership testing and eliminates duplicate values, making it useful for tasks such as removing duplicates or checking for common elements between sets.

In this article, we will learn how to access the K element in a set without deletion in python.

Example

Assume we have taken an input set and K element. We will now find the index of that K element in an input set using the above methods.

Input

inputSet = {3, 9, 5, 1, 2, 8}
k=5

Output

The index of given K{ 5 } in an input set: 3

In the above input set, the input K i.e, 5 is at the 3rd index in an input set. Hence the resultant k position in an input set is 3.

Methods Used

The following are the various methods to accomplish this task:

• Using for loop

• Using next() and iter() functions

• Using list() and index() functions

Method 1: Using for loop

In this method we are just going to use a simple for loop to access the K element in set without deleting any element in it

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task -.

• Create a variable to store the input set.

• Print the input set.

• Create another variable to store the input k value.

• Assume the initial result position as -1(as the index starts from 0).

• Use the for loop to traverse through each element of input set.

• Increment the result position by 1 inside the loop.

• Use the if conditional statement to check whether the current element is equal to the input k value.

• Break the loop if the condition is true.

• Print the resultant index of a given K element in an input set.

Example

The following program returns the index of a given K element in an input set using the for loop

# input set
inputSet = {3, 9, 5, 1, 2, 8}
# printing input set
print("Input Set:", inputSet)
# input k value
k = 5
# initializing the result position as -1(as index starts from 0)
resultPosition = -1
# traversing through each element of the input set
for e in inputSet:
    # incrementing the result position by 1
    resultPosition += 1
    # checking whether the current element is equal to the k
    if e == k:
        # breaking the loop if the condition is true
        break
# printing resultant index
print("The index of given K{", k, "} in an input set:", resultPosition)

Output

On executing, the above program will generate the following output

Input Set: {1, 2, 3, 5, 8, 9}
The index of given K{ 5 } in an input set: 3

Method 2: Using next() and iter() functions

In this method we are going to use next() and iter() function to access the k element in a set without deleting any other element

iter function()

Returns an iterator object. This function converts an iterable to an iterator.

Syntax

iter(object, sentinel)

Parameters

• object(required): It is an iterable object.

• sentinel(optional): It is a value that indicates the end of the sequence.

Return Value: returns an Iterator object

next() function

Returns the next item in an iterator like a list, string tuple, etc. If the iterable reaches its end, you can add a default return value to the return.

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task -.

• Use the iter() function to convert the input set to the iterator.

• Use the for loop to traverse through the length of the input set using the len() function(returns the number of items in an object).

• Incrementing the index/position of an input set to the next position using the next() function

• Use the if conditional statement to check whether the current element is equal to the input k value.

• Break the loop if the condition is true.

• Print the resultant index of a given K element in an input set.

Example

The following program returns the index of a given K element in an input set using next() and iter() functions

# input set
inputSet = {3, 9, 5, 1, 2, 8}
# printing input set
print("Input Set:", inputSet)
# input k value
k = 5
# converting input set to the iterator
setIter = iter(inputSet)
# traversing through the length of input set
for i in range(len(inputSet)):
    # incrementing the index/position of set to next position using next() function
    e = next(setIter)
    # checking whether the current element is equal to the k
    if e == k:
        # breaking the loop if the condition is true
        break
# printing resultant index
print("The index of given K{", k, "} in an input set:", i)

Output

On executing, the above program will generate the following output

Input Set: {1, 2, 3, 5, 8, 9}
The index of given K{ 5 } in an input set: 3

Method 3: Using list() and index() functions

In this example we are going to use a combination of list() and index functions of python to access the K element in a given set.

index() function

The position at the first occurrence of the provided value is returned by the index() function.

Syntax

list.index(element)

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task

• Use the list() function(converts the sequence/iterable to a list) to convert the input set into the list.

• Use the index() function to get the index of input k value from the above list of set elements by passing k to it.

• Print the resultant index of a given K element in an input set.

Example

The following program returns the index of a given K element in an input set using list() and index() functions -

inputSet = {3, 9, 5, 1, 2, 8}
# printing input set
print("Input Set:", inputSet)
# input k value 
k = 5
# converting input set into list 
setElementsList =list(inputSet)
# getting the index of input k value from the above list of set elements  
resultPosition = setElementsList.index(k)
# printing resultant index
print("The index of given K{",k,"} in an input set:", resultPosition)

Output

Input Set: {1, 2, 3, 5, 8, 9}
The index of given K{ 5 } in an input set: 3

Conclusion

In this article we have learned 3 different methods to Access the K element in the set without deletion. We learned how to use the iter() function to loop through the given iterable and the next() function to go to the following position of it. Finally, we learned how to create a list from the given set and how to use the index() function to locate an element's index within the set.