46 Simple Python Exercises : part 1

This was an original idea by generated by Torbjoern Lager – link I checked did not work but these are great ideas for learning python, you are supposed to come up with solutions to these exercises. There are many solutions already out there especially on github

Exercise 1 – Max of Two

Define a function max() that takes two numbers as arguments and returns the largest of them. Use the if-then-else construct available in Python. (It is true that Python has the max() function built in, but writing it yourself is nevertheless a good exercise.)

Exercise 2 – Max of Three

Define a function max_of_three() that takes three numbers as arguments and returns the largest of them.

Exercise 3 – Length of String

Define a function that computes the length of a given list or string. (It is true that Python has the len() function built in, but writing it yourself is nevertheless a good exercise.)

Exercise 4 – Vowel Checker

Write a function that takes a character (i.e. a string of length 1) and returns True if it is a vowel, False otherwise.

Exercise 5 – Swedish Robber Translator

Write a function translate() that will translate a text into “rövarspråket” (Swedish for “robber's language”). That is, double every consonant and place an occurrence of “o” in between. For example, translate(“this is fun”) should return the string “tothohisos isos fofunon”.

Exercise 6 – Sum and Multiply

Define a function sum() and a function multiply() that sums and multiplies (respectively) all the numbers in a list of numbers. For example, sum([1, 2, 3, 4]) should return 10, and multiply([1, 2, 3, 4]) should return 24.

Exercise 7 – Reverse a String

Define a function reverse() that computes the reversal of a string. For example, reverse(“I am testing”) should return the string “gnitset ma I”.

Exercise 8 – Is a Palindrome

Define a function is_palindrome() that recognizes palindromes (i.e. words that look the same written backwards). For example, is_palindrome(“radar”) should return True.

Exercise 9 – Is a member

Write a function is_member() that takes a value (i.e. a number, string, etc) x and a list of values a, and returns True if x is a member of a, False otherwise. (Note that this is exactly what the in operator does, but for the sake of the exercise you should pretend Python did not have this operator.)

Exercise 10 – Overlapping

Define a function overlapping() that takes two lists and returns True if they have at least one member in common, False otherwise. You may use your is_member() function, or the in operator, but for the sake of the exercise, you should (also) write it using two nested for-loops.

Exercise 11 – Generate n Chars

Define a function generate_n_chars() that takes an integer n and a character c and returns a string, n characters long, consisting only of c:s. For example, generate_n_chars(5,”x”) should return the string “xxxxx”. (Python is unusual in that you can actually write an expression 5 * “x” that will evaluate to “xxxxx”. For the sake of the exercise you should ignore that the problem can be solved in this manner.)

Exercise 12 – Histograms

Define a procedure histogram() that takes a list of integers and prints a histogram to the screen. For example, histogram([4, 9, 7]) should print the following:

xxxx
xxxxxxxxx
xxxxxxx

Exercise 13 – Max in List

The function max() from exercise 1) and the function max_of_three() from exercise 2) will only work for two and three numbers, respectively. But suppose we have a much larger number of numbers, or suppose we cannot tell in advance how many they are? Write a function max_in_list() that takes a list of numbers and returns the largest one.

Exercise 14 – Words into Integers

Write a program that maps a list of words into a list of integers representing the lengths of the correponding words.

Exercise 15 – Longest Word

Write a function find_longest_word() that takes a list of words and returns the length of the longest one.

Exercise 16 – Filter Long Words

Write a function filter_long_words() that takes a list of words and an integer n and returns the list of words that are longer than n.

Exercise 17 – Advanced Palindrome Checker

Write a version of a palindrome recognizer that also accepts phrase palindromes such as “Go hang a salami I'm a lasagna hog.”, “Was it a rat I saw?”, “Step on no pets”, “Sit on a potato pan, Otis”, “Lisa Bonet ate no basil”, “Satan, oscillate my metallic sonatas”, “I roamed under it as a tired nude Maori”, “Rise to vote sir”, or the exclamation “Dammit, I'm mad!”. Note that punctuation, capitalization, and spacing are usually ignored.

Exercise 18 – Pangram

A pangram is a sentence that contains all the letters of the English alphabet at least once, for example: The quick brown fox jumps over the lazy dog. Your task here is to write a function to check a sentence to see if it is a pangram or not.

Exercise 19 – 99 Bottles of Beer

“99 Bottles of Beer” is a traditional song in the United States and Canada. It is popular to sing on long trips, as it has a very repetitive format which is easy to memorize, and can take a long time to sing. The song's simple lyrics are as follows:

99 bottles of beer on the wall, 99 bottles of beer. Take one down, pass it around, 98 bottles of beer on the wall.

The same verse is repeated, each time with one fewer bottle. The song is completed when the singer or singers reach zero.

Your task here is write a Python program capable of generating all the verses of the song.

Exercise 20 – Swedish Translator

Represent a small bilingual lexicon as a Python dictionary in the following fashion {“merry”:”god”, “christmas”:”jul”, “and”:”och”, “happy”:gott”, “new”:”nytt”, “year”:”år”} and use it to translate your Christmas cards from English into Swedish.

That is, write a function translate() that takes a list of English words and returns a list of Swedish words.

Exercise 21 – Char Frequency

Write a function char_freq() that takes a string and builds a frequency listing of the characters contained in it. Represent the frequency listing as a Python dictionary.

Try it with something like char_freq(“abbabcbdbabdbdbabababcbcbab”).

Exercise 22 – Caesar's Cipher

In cryptography, a Caesar cipher is a very simple encryption techniques in which each letter in the plain text is replaced by a letter some fixed number of positions down the alphabet.

For example, with a shift of 3, A would be replaced by D, B would become E, and so on.

The method is named after Julius Caesar, who used it to communicate with his generals. ROT-13 (“rotate by 13 places”) is a widely used example of a Caesar cipher where the shift is 13. In Python, the key for ROT-13 may be represented by means of the following dictionary:

key = {‘a':'n', ‘b':'o', ‘c':'p', ‘d':'q', ‘e':'r', ‘f':'s', ‘g':'t', ‘h':'u', ‘i':'v', ‘j':'w', ‘k':'x', ‘l':'y', ‘m':'z', ‘n':'a', ‘o':'b', ‘p':'c', ‘q':'d', ‘r':'e', ‘s':'f', ‘t':'g', ‘u':'h', ‘v':'i', ‘w':'j', ‘x':'k', ‘y':'l', ‘z':'m', ‘A':'N', ‘B':'O', ‘C':'P', ‘D':'Q', ‘E':'R', ‘F':'S', ‘G':'T', ‘H':'U', ‘I':'V', ‘J':'W', ‘K':'X', ‘L':'Y', ‘M':'Z', ‘N':'A', ‘O':'B', ‘P':'C', ‘Q':'D', ‘R':'E', ‘S':'F', ‘T':'G', ‘U':'H', ‘V':'I', ‘W':'J', ‘X':'K', ‘Y':'L', ‘Z':'M'} Your task in this exercise is to implement an encoder/decoder of ROT-13. Once you're done, you will be able to read the following secret message:

Pnrfne pvcure? V zhpu cersre Pnrfne fnynq!

Note that since English has 26 characters, your ROT-13 program will be able to both encode and decode texts written in English.

Exercise 23 – Spell Check

Define a simple “spelling correction” function correct() that takes a string and sees to it that 1) two or more occurrences of the space character is compressed into one, and 2) inserts an extra space after a period if the period is directly followed by a letter.

E.g. correct(“This is very funny and cool.Indeed!”) should return “This is very funny and cool. Indeed!” Tip: Use regular expressions!