First, let's familiarize ourselves with Python's string type:

• Read a string input from the user's console (hint: input()); next sub-tasks will use this value and apply various string transformations on it;
• Print the reversed string (e.g., “hello world” ⇒ “dlrow olleh”); hint: there are at least 3 built-in ways to do this in a single line of code ;)
• Print the same string in “aLtErNaTe CaSe” (if you're out of ideas, simply use the for loop);
• Finally: encrypt the given message using Caesar's Cipher (aka, shift each of its alphabet letters to n positions to the: right for encryption, left for decryption); use the number 17' for testing!

Python is also popular for its numeric manipulation features (it can handle very large numbers!). Let's find out:

• Read a number from the console (you should know how to do it by now; don't forget to convert it to an int!);
• Reverse the number's digits and print the result (e.g., 13568 ⇒ 86531)!
• Define a new function, generate_prime(k), which takes in an argument and will generate a prime number of exactly k digits; use it to generate a 15-digit prime number (decrease this if it's taking too long :( )!

Solve these subtasks all in the same file (use print() statements to display the results):

Use the following list:

sample = ["a", 90, 8, "X55", "1z", 102, "asdf", 65, 10, "word", "567", 567]

Well:

• Sort the list (does it work? if not, why?);
• Reverse the list (this again? note: save the original one!);
• Filter out all non-numbers from the list (i.e., only int type values should remain)… can you make it using a single line of code? now it's the time to introduce list comprehensions;

• Print the original list (remember the first 2 subtasks? read this answer!);
• Define a function that builds a matrix filled with numbers from 1 to n like the following example:

  m = [[1, 2, 3, 4],
       [4, 1, 2, 3],
       [3, 4, 1, 2],
       [2, 3, 4, 1]]

First, take a couple (3-4) of paragraphs from here and store them inside a .txt file.

• Open the file and read its contents into string;
• Build a dict with each word from this text (lower cased as key), counting their frequency (as its value);
• Use it to print out the most frequent 5 words in this text (together with their value!), e.g.:

[('the', 29), ('of', 18), ('and', 15), ('to', 10), ('a', 9)]

What else can you do easily using Python… ?

Let's try this one:

• fetch the lyrics of your favorite song from this site.

• Extract just the lyrics part from the HTML code and print it to the console! (also, please get rid of those <br> line break tags, replace them with newlines instead).