Learn Iterating with range() Function

Imagine you have a list of travel destinations and you want to work with only a specific part of it. For example, you might want to visit just the first three cities or print destinations in reverse order. Python's range() function can help you iterate over the indices of the list easily!

The range() function is useful when working with list indices;
It allows you to control the start, end, and step of iteration;
Instead of iterating directly over the items, you iterate over the positions of items in a sequence.

The format of the range() function is:

range(start, end, step)

start: the starting index of the range (default is 0 if omitted);
end: the ending index (exclusive);
step: the increment between indices (default is 1).

Suppose we have a list of cities we want to visit. Let's print the first three destinations using range():


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# List of travel destinations
travel_list = ['Monako', 'Luxemburg', 'Liverpool', 'Barcelona', 'Munchen']

# Printing the first three destinations
for i in range(3):
    print(i, ':', travel_list[i])

range(3) generates numbers from 0 to 2 (end value 3 is exclusive);
Inside the loop, travel_list[i] accesses the destination at index i.

Let's print the travel destinations in reverse order:


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

# Printing travel destinations in reverse
# Start at last index, end at -1, step -1
for i in range(len(travel_list) - 1, -1, -1): 
    print(i, ':', travel_list[i])

len(travel_list) calculates the number of items in the list (5 in this case).
range(len(travel_list) - 1, -1, -1) generates indices from 4 to 0, allowing iteration in reverse order.
The loop prints each index and its corresponding destination from travel_list, displaying the locations in reverse.

Note

Often, we don't know the length of a list in advance. To handle this, we calculate the length of the list using the len() function.

Since Python's list indexing starts at 0, the last element's index is always len(list) - 1. For example, if a list has 5 elements, the last element is at index 4 (not 5).

Task

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You and your friends are planning a group trip, but you decide to split up to visit different countries and cover more ground. You agree to visit the countries whose indexes are divisible by 2, while your friends will visit the rest.

Use the range function correctly to set up the start, end, and step values.
Fill the your_travel_list with the indexes of countries that are divisible by 2.

Solution

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Section 1. Chapter 2

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The range() function is useful when working with list indices;
It allows you to control the start, end, and step of iteration;
Instead of iterating directly over the items, you iterate over the positions of items in a sequence.