# Two ways to find the set difference in Python

# Python program to find the difference between two sets :

In this python programming tutorial, we will learn how to find the *difference* between *two* sets. The difference between *set A* and *set B* is a *set* that contains only *the elements from set A those are not in set B*. In this example, we will take the inputs from the user for both sets. The program will calculate the difference and print it out.

## 1. Using difference() method :

For finding out the difference between two sets, python has one inbuilt method *difference()*. The syntax of the method is as below :

A.difference(B)

As you can see, it takes *one set* as the parameter. It calculates the difference between *A and B *i.e. *A – B* and returns one new set. Note that this method *doesn’t modify* the original set.

### Example Program :

#1 setA = set() setB = set() #2 setA_length = int(input(“Enter the size of the first set : “)) setB_length = int(input(“Enter the size of the second set : “)) #3 print(“\n”) print(“Enter values for the first set : \n”) for i in range(setA_length): e = int(input(“Enter value {} : “.format(i+1))) setA.add(e) #4 print(“\n”) print(“Enter values for the second set : \n”) for i in range(setB_length): e = int(input(“Enter value {} : “.format(i+1))) setB.add(e) #5 print(“\n”) print(“First set : {}”.format(setA)) print(“Second set : {}”.format(setB)) print(“Difference : {}”.format(setA.difference(setB)))

### Explanation :

*The commented numbers in the above program denote the step numbers below :*

- Create two empty set
*setA*and*setB*. - Ask the user to enter the
*size*of both sets. Read and store the values. - Get the inputs for the first set from the user. Add them all to
*setA*. - Similarly, get the inputs and add to the second set
*setB*. - Print out the first set, second set and difference between them using the
*difference*method.

### Sample Output :

Enter the size of the first set : 3 Enter the size of the second set : 1 Enter values for the first set : Enter value 1 : 1 Enter value 2 : 2 Enter value 3 : 3 Enter values for the second set : Enter value 1 : 2 First set : {1, 2, 3} Second set : {2} Difference : {1, 3}

## 2. Using ‘-‘ operator :

Instead of using the *difference()* method, we can also use *’-‘* to find out the difference between the two sets.

setA = set() setB = set() setA_length = int(input(“Enter the size of the first set : “)) setB_length = int(input(“Enter the size of the second set : “)) print(“\n”) print(“Enter values for the first set : \n”) for i in range(setA_length): e = int(input(“Enter value {} : “.format(i+1))) setA.add(e) print(“\n”) print(“Enter values for the second set : \n”) for i in range(setB_length): e = int(input(“Enter value {} : “.format(i+1))) setB.add(e) print(“\n”) print(“First set : {}”.format(setA)) print(“Second set : {}”.format(setB)) print(“Difference : {}”.format(setA - setB))

*The above examples are available on Github*

### Sample Output :

Enter the size of the first set : 4 Enter the size of the second set : 2 Enter values for the first set : Enter value 1 : 0 Enter value 2 : 1 Enter value 3 : 2 Enter value 4 : 3 Enter values for the second set : Enter value 1 : 0 Enter value 2 : 3 First set : {0, 1, 2, 3} Second set : {0, 3} Difference : {1, 2}

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