Learn Nested for Loop | Nested Loops

We will use a nested loop to print each city multiple times in a structured format, resembling a triangle pattern.


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travel_list = ['Monako', 'Luxemburg', 'Liverpool', 'Barcelona', 'Munchen']

# Outer loop for controlling rows
for i in range(1, len(travel_list) + 1):
    # Inner loop for controlling columns
    for j in range(i):
        print(travel_list[j], end=' ')  # Print cities in a row
    print('')  # Move to the next line after each row

Outer loop: the for loop with range(1, len(travel_list) + 1) determines the number of rows. Each iteration represents a row. i controls how many cities are printed in the current row;
Inner loop: the for loop with range(i) iterates over the cities to be printed in the current row. j accesses the city names in the travel_list up to the current row index;
Printing: the print(travel_list[j], end=' ') ensures cities are printed on the same row. print('') moves to the next line after each row.

Using a nested loop, you can iterate through a nested list and interact with each of its elements.


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# Define a nested list containing sublists with words starting with 'A' and 'T'
nested_list = [
    ["Apple", "Avocado", "Apricot"],
    ["Tomato", "Tangerine", "Tea"],
    ["Almond", "Thyme", "Tuna"]
]

# Iterate through each sublist in the nested list
for sublist in nested_list:
    # Iterate through each item in the current sublist
    for item in sublist:
        # Convert the item to lowercase and print it
        print(item.lower(), end=' ')

Task

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You are working on a navigation system that processes lists of trips, where each trip includes multiple countries. However, a data processing error has caused all country names to appear in lowercase, making them unreadable by the system.
To fix this issue, you need to extract and format the country names correctly.

Extract all country names from trips and store them in countries.
Capitalize each country name before adding it to countries using capitalize() method.

Solution

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Section 3. Chapter 1

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