Think Python - Denison University

82 Chapter 9. Casestudy: word playThe next word is “aah,” which is a perfectly legitimate word, so stop looking at me like that. Or, ifit’sthewhitespace that’sbothering you, wecan get ridofit withthe stringmethodstrip:>>> line = fin.readline()>>> word = line.strip()>>> print wordaahedYou can also use a file object as part of a for loop. This program reads words.txt and prints eachword, one per line:fin = open('words.txt')for line in fin:word = line.strip()print wordExercise 9.1 Write a program that reads words.txt and prints only the words with more than 20characters (not counting whitespace).9.2 ExercisesTherearesolutionstotheseexercisesinthenextsection. Youshouldatleastattempteachonebeforeyou read thesolutions.Exercise9.2 In1939ErnestVincentWrightpublisheda50,000wordnovelcalledGadsbythatdoesnot contain theletter “e.” Since “e” isthe most common letterinEnglish, that’s not easy todo.In fact, it is difficult to construct a solitary thought without using that most common symbol. It isslow going at first,but withcaution and hours oftraining you can gradually gain facility.Allright, I’llstopnow.Write a function called has_no_e that returns True if the given word doesn’t have the letter “e” init.Modifyyourprogramfromtheprevioussectiontoprintonlythewordsthathaveno“e”andcomputethepercentage of the words inthelisthave no “e.”Exercise9.3 Writeafunctionnamedavoidsthattakesawordandastringofforbiddenletters,andthat returnsTrueiftheword doesn’t use any of the forbidden letters.Modify your program to prompt the user to enter a string of forbidden letters and then print thenumber of words that don’t contain any of them. Can you find a combination of 5 forbidden lettersthat excludes thesmallestnumber of words?Exercise 9.4 Write a function named uses_only that takes a word and a string of letters, and thatreturns True if the word contains only letters in the list. Can you make a sentence using only thelettersacefhlo? Other than “Hoe alfalfa?”Exercise 9.5 Write a function named uses_all that takes a word and a string of required letters,and that returns True if the word uses all the required letters at least once. How many words arethere that useall thevowelsaeiou? How aboutaeiouy?