Data Structures in Python

Dictionaries are unordered, Mutable collections of data, where the data is stored in the form of key:value pairs. The values can be accessed directly if their keys are known, without having to iterate over. The data is enclosed in curly brackets. The values can be mutable and repetitive, but keys have to be unique and immutable.

Use Case: Dictionaries are useful when you need instant access to data, without having to iterate over all the values. For example, employee data can be stored in dictionaries.

Let’s create a dictionary:

Employee={'Id':1,'Name':'Tom','Age':30,'Education':'Masters','Department':'IT','Salary':100000}

Dictionary Operations

#Accessing Elements
Employee['Name']   #output: Tom

#Finding keys using 'IN' Operator
'Education' in Employee  #output: True

#Viewing Keys 
Employee.keys()  #output: dict_keys(['Id', 'Name', 'Age', 'Education', 'Department', 'Salary'])

#Viewing Values
Employee.values()   #output: dict_values([1, 'Tom', 30, 'Masters', 'IT', 100000])

• Adding Elements

Employee['Bonus']='Yes'    # Syntax: dictionary['newkey']='value'

• Deleting Elements

Sets

Sets are unordered, mutable collections of data, which can’t contain repeated values. They can take different data types, and are enclosed by curly braces {}.

Use Case: Sets are helpful for performing mathematical operations on the data, and when you need to store distinct values.

Let’s create a Set of Genres:

Genres= {"Fiction", "NonFiction", "Drama", "Poetry"}
#output: {'Drama', 'Fiction', 'NonFiction', 'Poetry'}  #notice how sets are sorted automatically

Set Operations

• Adding Items to a Set

Genres.add("Folktale")

#Adding Multiple Items

Genres.update(['Horror','Distopian','SciFi'])

#output: {'Distopian','Drama','Fiction','Folktale','Horror','NonFiction','Poetry','SciFi'}

• Removing Items from a Set

Genres.remove("Poetry")       # .remove() deletes an item, and raises an Error 
                                 if it doesn't already exist in the set
Genres.discard("Thriller")    # .discard() deletes an item in a set, 
                                 but in case the item doesn't exist, it doesn't return an error

• Mathematical Operations on Sets

#Let's create two sets

Set1={1,2,3,4,5}
Set2={4,5,6,7,8}

#Intersection

Set1 & Set2              #Use '&' for intersection
#output: {4, 5}

Set1.intersection(Set2)  # or use .intersection() to find common elements

#Union

Set1.union(Set2)  
#output: {1, 2, 3, 4, 5, 6, 7, 8}

#Let's create another Set

Set3={1,2,3}

#Subset

Set3.issubset(Set1)              #check if subset
#output: True         

#Superset

Set1.issuperset(Set3)    #check if superset
#output: True

#Difference

Set1.difference(Set2)     # finds how different Set1 is from Set2 
#output: {1, 2, 3}

Conclusion: