How to solve these coding challenges:

• Write your solution in PyCharm or in your preferred Python IDE.

• If your solution is not correct, then try to understand the error messages, watch the video again, rewrite the solution, and test it again. Repeat this step until you get the correct solution.

• Save the solution in a file for future reference or recap.

Challenge #1

• Consider this text file that contains multiple duplicate MAC addresses.

• Create a new file that contains only unique MAC addresses. Each MAC should be on its own line.

Are you stuck? Do you want to see the solution to this exercise? Click here.

Challenge #2

• Create a Python script that reads a text file into a list and then converts the list into a string that has the entire file content.

Click to download a sample text file.

Are you stuck? Do you want to see the solution to this exercise? Click here.

Challenge #3

• Create a Python script that removes all empty lines including those that contain only spaces from a file.

Click to download a sample text file.

Are you stuck? Do you want to see the solution to this exercise? Click here.

Challenge #4

• Create a Python function called tail that reads the last n lines of a text file. The function has two arguments: the file name and n (the number of lines to read). This is similar to the Linux `tail` command.

Example: tail('sample_file.txt', 5) will return the last 5 lines from sample_file.txt.

Click to download a sample text file.

Are you stuck? Do you want to see the solution to this exercise? Click here.

Challenge #5

• Change the solution from the previous challenge so that the script that prints out the last n lines of the file refreshes the output every 3 seconds (as the file changes or updates). This is similar to the tail -f Linux command.

Click to download a sample text file.

Are you stuck? Do you want to see the solution to this exercise? Click here.

Challenge #6

• Write a Python program to count the number of lines, words, and characters in a text file. This is similar to the Linux `wc` command. Create a function, if possible.

Click to download a sample text file.

Are you stuck? Do you want to see the solution to this exercise? Click here.

Challenge #7

• Write a Python program that calculates the net amount of a bank account based on the transactions that are saved in a text file.

The file format is as follows:

D:50

W:100

D means deposit while W means withdrawal.

Suppose that the following file is supplied to the program:

D:300

D:300

W:500

D:200

Then, the output should be: 300

Are you stuck? Do you want to see the solution to this exercise? Click here.

Challenge #8

• Write a Python script that compares line by line two text files and displays the lines that differ.

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Challenge #9

• Consider this dictionary file.

• Write a Python script that reads the file in a dictionary. The words in the file will be the dictionary keys and the length of each word the corresponding values.

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Challenge #10

• Consider the dictionary file from the previous challenge.

• Write a Python script that finds the first 100 longest words in the file.

Tip: See how to get a sorted view of a dictionary.

Are you stuck? Do you want to see the solution to this exercise? Click here.

Challenge #11

• Consider this dictionary file.

• Write a Python script that finds the number of occurrences of each letter of the alphabet in all the words of the dictionary. Make a distinction between lower and uppercase letters.

• You want to see how many times 'a', 'A', 'b', 'B', 'c', 'C', 'd' and so on appear in all the words in the dictionary.

• Which is the most frequently used letter in English words? But the least frequently used one?

Are you stuck? Do you want to see the solution to this exercise? Click here.

Challenge #12

• Change the solution from the previous challenge so that the script considers all letters lowercase (it makes no distinction between lower and uppercase letters).

Are you stuck? Do you want to see the solution to this exercise? Click here.

Challenge #13

• Continue the previous challenge and find the 3 most frequently used letters in all English Words.

• You should get: ('e', 67681), ('s', 50872), ('i', 50818)

Are you stuck? Do you want to see the solution to this exercise? Click here.