# Set and Booleans¶

There are two other object types in Python that we should quickly cover: Sets and Booleans.

## Sets¶

Sets are an unordered collection of unique elements. We can construct them by using the set() function. Let's go ahead and make a set to see how it works

In [1]:
x = set()

In [2]:
# We add to sets with the add() method

In [3]:
#Show
x

Out[3]:
{1}

Note the curly brackets. This does not indicate a dictionary! Although you can draw analogies as a set being a dictionary with only keys.

We know that a set has only unique entries. So what happens when we try to add something that is already in a set?

In [4]:
# Add a different element

In [5]:
#Show
x

Out[5]:
{1, 2}
In [6]:
# Try to add the same element

In [7]:
#Show
x

Out[7]:
{1, 2}

Notice how it won't place another 1 there. That's because a set is only concerned with unique elements! We can cast a list with multiple repeat elements to a set to get the unique elements. For example:

In [8]:
# Create a list with repeats
list1 = [1,1,2,2,3,4,5,6,1,1]

In [9]:
# Cast as set to get unique values
set(list1)

Out[9]:
{1, 2, 3, 4, 5, 6}

## Booleans¶

Python comes with Booleans (with predefined True and False displays that are basically just the integers 1 and 0). It also has a placeholder object called None. Let's walk through a few quick examples of Booleans (we will dive deeper into them later in this course).

In [10]:
# Set object to be a boolean
a = True

In [11]:
#Show
a

Out[11]:
True

We can also use comparison operators to create booleans. We will go over all the comparison operators later on in the course.

In [12]:
# Output is boolean
1 > 2

Out[12]:
False

We can use None as a placeholder for an object that we don't want to reassign yet:

In [13]:
# None placeholder
b = None

In [14]:
# Show
print(b)

None


Thats it! You should now have a basic understanding of Python objects and data structure types.