Crus4

# Python Sets

In Python, a Set is an unordered collection of unique elements, that means duplicate elements are not allowed in a Set. Set is one of the 4 built-in data types in Python, the other 3 are List, Tuple and Dictionary.

Sets in Python are created by placing all the elements inside curly braces `{...}`, separated by commas. A Set can include items of different data types, like Integers, Float, Strings.

Here is how you can create a Set, in Python.

Example

```my_set = {"apple", 5, 3.14, True}
print(my_set) #Outputs: {True, 3.14, 5, 'apple'}```

### Get Length of a Set

In order to calculate how many items are present in a set, we can use the `len()` function. Here is an example:

Example

```my_set = {"apple", "orange", "mango", "grapes"}
print(len(my_set)) #Outputs: 4
set2 =  {"a", 2, 6.14, True, "grapes"}
print(len(set2)) #Outputs: 5```

### Duplicate items in a Set

We already discussed duplicate items are not allowed in a Set. Now let’s see what happen if we add duplicate items in a set.

Example

```my_set = {"apple", "banana", "mango", "apple"}
print (my_set) #Outputs: {'apple', 'mango', 'banana'}```

As you can see that, when we run this code it prints duplicate item only once.

Also remember that 1 and True are same.

Example

```my_set = {"apple", "banana", "watermelon", "apple", True, 1}
print (my_set) #Outputs: {True, 'watermelon', 'banana', 'apple'}```

### Python Sets – Add items

Python Sets are mutable, which means we can modify them by adding or removing items. We cannot directly modify individual items within a set, we need to remove the item that we want to modify and add the modified item back to the set. Here is an example:

Example

```my_set = {"apple", "banana", "cherry"}
# Remove item you want to modify
my_set.remove("banana")

# Add the modified item back to the set

print(my_set)  # Outputs: {"apple", "cherry", "banana"}```

### Access Set Items

We cannot access set items by referring to an index, like we did in Lists and tuples. Infact we have to iterate over a Set or by using specific methods to access Set items. Here is an example:

Example

```my_set = {"apple", "banana", "cherry"}

for item in my_set:
print(item)
"""Outputs:
apple
banana
cherry
"""```

### Check if an item is Present in a Set

To check if any specific item is present in a set or not we can use the in operator. It returns True if an item is present in a Set, otherwise False. Here is an example:

Example

```my_set = {"apple", "banana", "cherry"}

print ("banana" in set) #Outputs: True
print ("mango" in set) #Outputs: False```