The First For Loop

Using loops you can iterate over sequences like lists, strings, or numerical ranges, they allow to process large amounts of data with minimal code.

item is a variable that takes the value of each element in the sequence one at a time;
sequence is the data you are iterating through, such as a list, string, or range;
for statement block is executed for every item in the sequence.

Imagine you have a string variable and want to print each letter of it in a column. Since a string is a sequence of letters, you can use a loop to achieve this.


              12345
            
word = 'iteration'

# Printing every letter in the city's name
for letter in word:
    print(letter)

word variable holds the string 'iteration';
for loop iterates over each character in the string;
letter takes the value of the next character in the string in each iteration;
print(letter) statement outputs the current character to the console.

Make sure to name the item variable meaningfully. For example, if you iterate through a list called people, the appropriate variable name should be person.

Task

Swipe to start coding

You are a traveler who keeps track of countries you want to visit in countries list and those you have already visited in visited_countries. As you travel, it becomes harder to manage everything, so you decide to automate this process.

Update travel_list to include only the countries from countries that are not in visited_countries.

Solution

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Section 1. Chapter 1

The First For Loop

Using loops you can iterate over sequences like lists, strings, or numerical ranges, they allow to process large amounts of data with minimal code.

item is a variable that takes the value of each element in the sequence one at a time;
sequence is the data you are iterating through, such as a list, string, or range;
for statement block is executed for every item in the sequence.

Imagine you have a string variable and want to print each letter of it in a column. Since a string is a sequence of letters, you can use a loop to achieve this.


              12345
            
word = 'iteration'

# Printing every letter in the city's name
for letter in word:
    print(letter)

word variable holds the string 'iteration';
for loop iterates over each character in the string;
letter takes the value of the next character in the string in each iteration;
print(letter) statement outputs the current character to the console.

Make sure to name the item variable meaningfully. For example, if you iterate through a list called people, the appropriate variable name should be person.

Task

Swipe to start coding

Update travel_list to include only the countries from countries that are not in visited_countries.

Solution

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

Section 1. Chapter 1

Switch to desktop for real-world practiceContinue from where you are using one of the options below