Fall 2024 - P3
3.2.2 Data Types Part 2
None
Tuples
A tuple is an immutable ordered collection of elements. Unlike lists, tuples cannot be modified after their creation, making them useful for storing fixed collections of items.
# Example of tuple operations in Python
# Creating a tuple
my_tuple = (10, 20, 30, "Hello")
print("Initial Tuple:", my_tuple) # Output: Initial Tuple: (10, 20, 30, "Hello")
# Accessing elements
first_element = my_tuple[0] # 10
print("First Element:", first_element) # Output: First Element: 10
# Length of the tuple
length = len(my_tuple)
print("Length of the Tuple:", length) # Output: Length of the Tuple: 4
# Concatenation
another_tuple = (40, 50)
concatenated = my_tuple + another_tuple
print("Concatenated Tuple:", concatenated) # Output: Concatenated Tuple: (10, 20, 30, "Hello", 40, 50)
# Repetition
repeated = my_tuple * 2
print("Repeated Tuple:", repeated) # Output: Repeated Tuple: (10, 20, 30, "Hello", 10, 20, 30, "Hello")
# Attempting to modify a tuple (will raise an error)
# Uncommenting the line below will result in a TypeError
my_tuple[1] = 25 # This will result in a TypeError
Initial Tuple: (10, 20, 30, 'Hello')
First Element: 10
Length of the Tuple: 4
Concatenated Tuple: (10, 20, 30, 'Hello', 40, 50)
Repeated Tuple: (10, 20, 30, 'Hello', 10, 20, 30, 'Hello')
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
Cell In[7], line 32
27 print("Repeated Tuple:", repeated) # Output: Repeated Tuple: (10, 20, 30, "Hello", 10, 20, 30, "Hello")
30 # Attempting to modify a tuple (will raise an error)
31 # Uncommenting the line below will result in a TypeError
---> 32 my_tuple[1] = 25 # This will result in a TypeError
TypeError: 'tuple' object does not support item assignment
%%javascript
// Although JavaScript doesn't have a built-in tuple type,
// we can use arrays to emulate tuple behavior.
// Creating a tuple-like array
let myTuple = [10, "Hello", true];
console.log("Initial Tuple:", myTuple); // Output: Initial Tuple: [10, "Hello", true]
// Accessing elements
let firstElement = myTuple[0]; // 10
console.log("First Element:", firstElement); // Output: First Element: 10
// Length of the tuple-like array
let length = myTuple.length;
console.log("Length of the Tuple-like Array:", length); // Output: Length of the Tuple-like Array: 3
Dictionaries
A dictionary is a collection of key-value pairs, where each key is unique. It allows you to store and retrieve data based on a key rather than an index, like in a list.
person = {
"name": "Alice",
"age": 25,
"city": "New York"
}
print(person["name"]) # Output: Alice
Alice
%%javascript
// Define a dictionary (object) to store student information
let students = {
"Alice": {
"age": 25,
"isStudent": true,
"courses": ["Math", "Science"]
},
"Bob": {
"age": 22,
"isStudent": true,
"courses": ["History", "Art"]
},
"Charlie": {
"age": 28,
"isStudent": false,
"courses": []
}
};
// Accessing information from the dictionary
console.log("Alice's age: ", students["Alice"]["age"]); // Output: Alice's age: 25
console.log("Bob's courses: ", students["Bob"]["courses"]); // Output: Bob's courses: ["History", "Art"]
// Adding a new student to the dictionary
students["David"] = {
"age": 24,
"isStudent": true,
"courses": ["Computer Science", "Physics"]
};
// Modifying information
students["Alice"]["isStudent"] = false; // Alice is no longer a student
console.log("Updated Alice's information: ", students["Alice"]);
// Output: Updated Alice's information: {age: 25, isStudent: false, courses: ["Math", "Science"]}
Sets
- A set is an unordered collection of unique items. Sets are useful when you want to ensure that there are no duplicate elements.
- Sets are unordered and unindexed. You cannot access elements by position.
- Sets automatically remove duplicates.
fruits = {"apple", "banana", "orange"}
print(fruits) # Output: {'banana', 'apple', 'orange'} (order is not guaranteed)
# Adding a new item to a set
fruits.add("grape")
print(fruits) # Output: {'banana', 'grape', 'apple', 'orange'}
# Duplicate items are ignored
fruits.add("apple")
print(fruits) # Output: {'banana', 'grape', 'apple', 'orange'}
{'banana', 'orange', 'apple'}
{'banana', 'orange', 'grape', 'apple'}
{'banana', 'orange', 'grape', 'apple'}
%%javascript
// Creating a new Set with some initial values
let fruits = new Set(["apple", "banana", "orange"]);
// Adding values to the Set
fruits.add("grape");
fruits.add("banana"); // This won't be added again since it's a duplicate
// Display the contents of the Set
console.log(fruits); // Output: Set(4) {"apple", "banana", "orange", "grape"}
// Deleting an item from the Set
fruits.delete("orange");
console.log("After deleting 'orange':", fruits); // Output: Set(3) {"apple", "banana", "grape"}
Booleans
A boolean is a data type that can have one of two values: True or False. Booleans are commonly used in conditional statements to control the flow of programs.
is_sunny = True
is_raining = False
if is_sunny:
print("Go outside!") # Output: Go outside!
Go outside!
%% javascript
// Simple boolean values
let isStudent = true;
let isLoggedIn = false;
// Check conditions with booleans
if (isStudent) {
console.log("The user is a student.");
} else {
console.log("The user is not a student.");
}
// Output: The user is a student.
None
None is a special constant in Python that represents the absence of a value or a null value. It’s commonly used as a placeholder for optional or yet-to-be-assigned values. It is also used to indicate “no value” or “empty”
val = None
print(val is None) # Output: True
True
let val = null;
console.log(val === null); // Output: true
Popcorn Hack: create a dictionary, update an item, and add an item
# Creating dictionary
person = {
"name": "Alice",
"age": 25,
"is_student": False
}
person["age"] = 26 # Update item
# Adding an item
person["David"] = {
"name": "David",
"age": 22,
"is_student": True
}