# for loops
# About for loops
# for loops are used to iterate over a sequence (list, tuple, string) or other
# iterable objects.
# Syntax
# for variable in sequence:
# code block
# Examples
# Iterate over a list
# A list is a collection which is ordered and changeable.
print("\nIterate over a list")
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
print(fruit)
# Output
# apple
# banana
# cherry
# Iterate over a string
# A string is a sequence of characters
print("\nIterate over a string")
for letter in "apple":
print(letter)
# Output
# a
# p
# p
# l
# e
# Iterate over a range
# A range is a sequence of numbers, starting from 0 by default, and increments
print("\nIterate over a range")
for i in range(5):
print(i)
# Output
# 0
# 1
# 2
# 3
# 4
# Note: The range() function returns a sequence of numbers, starting from 0
# by default, and increments by 1 (by default), and stops before a
# specified number.
# Iterate over a tuple
# A tuple is a collection which is ordered and unchangeable.
print("\nIterate over a tuple")
colors = ("red", "green", "blue")
for color in colors:
print(color)
# Output
# red
# green
# blue
# Iterate over a dictionary
# A dictionary is a collection which is unordered, changeable and indexed.
print("\nIterate over a dictionary")
person = {
"name": "Alice",
"age": 25,
"is_active": True
}
for key in person:
print(key, person[key])
# Output
# name Alice
# age 25
# is_active True
# Note: The for loop iterates over the keys of the dictionary.
# Iterate over a dictionary using items() method
# The items() method returns a view object that displays a list of a given
# dictionary's key-value tuple pair.
print("\nIterate over a dictionary using items() method")
for key, value in person.items():
print(key, value)
# Output
# name Alice
# age 25
# is_active True
# Note: The for loop iterates over the key-value pairs of the dictionary.
if key == "age" and value >= 18:
print(person["name"], "is an adult.")
# Iterate over a dictionary using values() method
# The values() method returns a view object that displays a list of all the
# values in the dictionary.
print("\nIterate over a dictionary using values() method")
for value in person.values():
print(value)
# Output
# Alice
# 25
# True
# Note: The for loop iterates over the values of the dictionary.
# Iterate over a dictionary using keys() method
# The keys() method returns a view object that displays a list of all the keys
# in the dictionary.
print("\nIterate over a dictionary using keys() method")
for key in person.keys():
print(key)
# Output
# name
# age
# is_active
# Note: The for loop iterates over the keys of the dictionary.
# Iterate over a dictionary using get() method
# The get() method returns the value of the specified key.
print("\nIterate over a dictionary using get() method")
print(person.get("name"))
# Nested for loops
# clients
clients = [
{"name": "Alice", "age": 25},
{"name": "Bob", "age": 30},
{"name": "Charlie", "age": 35}
]
# products
products = ["apple", "banana", "cherry"]
inventory = {
"apple": 10,
"banana": 20,
"cherry": 30
}
# orders
orders = [
{"client": "Alice", "product": "apple"},
{"client": "Bob", "product": "banana"},
{"client": "Charlie", "product": "cherry"}
]
# Iterate over clients
print("\nIterate over clients")
for client in clients:
print(client["name"], client["age"])
# Output
# Alice 25
# Bob 30
# Charlie 35
# Iterate over products
print("\nIterate over products")
for product in products:
print(product)
# Output
# apple
# banana
# cherry
# Iterate over orders
print("\nIterate over orders")
for order in orders:
print(order["client"], order["product"])
# Output
# Alice apple
# Bob banana
# Charlie cherry
# Iterate over orders and products and update inventory
print("\nIterate over orders and products and update inventory")
for order in orders:
for product in products:
if order["product"] == product:
inventory[product] -= 1
print(order["client"], "ordered", order["product"])
print("Inventory of", product, "is", inventory[product])
# Output
# Alice ordered apple
# Inventory of apple is 9
# Bob ordered banana
# Inventory of banana is 19
# Charlie ordered cherry
# Inventory of cherry is 29
# Note: The nested for loop iterates over the orders and products and updates
# the inventory of the products.
`for` loops in Python
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