# Python Little Goal 10

Python Day 16

### 1. distinct Average

suppose we want to find the distinct average of a list.
Key: we need to use SET function.

```def average(array):
sum1=sum(set(array))
n=len(set(array))
return(sum1/n)``` 12019 / Pixabay

### 2. Symmetric Difference

#### Challenge: List the Symmetric Difference integers for two sets in ascending order, one per line.

Before we solve the challenge, we will go over some basic Set operations in Python.

Set:

```a=input()
5 4 3 2
list1=a.split()
print(list1)
['5', '4', '3', '2']
```

MAP: convert the strings to integers

```newlist=list(map(int,list1))
pprint(newlist)
[5,4,3,2]```

Creating set

```#1. Directly assigning values to a set
myset = {1, 2}

#2.Creating a set from a list
myset = set()  # Initializing a set
myset = set(['a', 'b'])
myset
{'a', 'b'}```

Modifying Sets

We will show the functions: Add, Update, and Remove

```#1.Add values to a set

#2. Update a set value
myset.update([1,2,3,4]) #update only works for iterable objects
myset
{"a", "b", "c", 1,2,3,4}

#3. Remove items
myset.discar(1)
myset
{"a", "b", "c", 2,3,4}

```

Common Set Operations:

We will introduce 3 basic set operations: Union, Intersection, Difference.

```#1. Union: values in a or b
a = {2, 4, 5, 9}
b = {2, 4, 11, 12}
a.union(b) #order doesn't matter
{2, 4, 5, 9, 11, 12}

#2. Intersection: values in a and b
a.intersection(b) #order doesn't matter
{2,4}

#3. Difference: values in a but not in b
a.difference(b) #order does matter
{9,5}```

Now, back to our original challenge, we will use the difference function to solve the problem

```a,b = [set(input().split()) for _ in range(4)][1::2]
bd=b.difference(a)
print('\n'.join(sorted(c, key=int)))

#Alternative solution
print ('\n'.join(sorted(a^b, key=int)))```

Reference: