Quiz 1

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Copyright 2021 Allen Downey, MIT License

Setup

The following cells download a file that contains a list of words, reads the words, and stores them in a set.

from os.path import basename, exists

def download(url):
    filename = basename(url)
    if not exists(filename):
        from urllib.request import urlretrieve
        local, _ = urlretrieve(url, filename)
        print('Downloaded ' + local)
    
download('https://github.com/AllenDowney/DSIRP/raw/main/american-english')
def read_words(filename):
    """Read lines from a file and split them into words."""
    res = set()
    for line in open(filename):
        for word in line.split():
            res.add(word.strip().lower())
    return res
word_list = read_words('american-english')
len(word_list)
100781

Question 1

The following function takes a string and returns True if the letters in the string appear in alphabetical order.

def is_alphabetical(word):
    return list(word) == sorted(word)
is_alphabetical('almost') # True
True
is_alphabetical('alphabetical') # False
False

Make a new list called alpha_words that contains only the words in word_list that are alphabetical, and display the length of the list.

Question 2

Find and display the longest word in alpha_words. If there is more than one word with the maximal length, you can display any one of them (but only one).

NOTE: You can write code for this question even if your answer to the previous question doesn’t work. I’ll grade the code, not the output.

Question 3

Write a function called encompasses that takes two words and returns True if the first word contains the second word, but not at the beginning or the end (and False otherwise). For example, hippopotomus encompasses the word pot.

HINT: You might find the string method find useful.

'hippopotomus'.find('pot')
5
'hippopotomus'.find('potato')
-1
# WRITE YOUR FUNCTION HERE

You can use the following examples to test your function.

word1 = 'hippopotamus'
word2 = 'pot'
word3 = 'hippo'
word4 = 'mus'
word5 = 'potato'
encompasses(word1, word2) # True
True
encompasses(word1, word3) # False because word3 is at the beginning
False
encompasses(word1, word4) # False because word4 is at the end
False
encompasses(word1, word5) # False because word5 is not in word1
False

Question 4

Two words make a “reverse pair” if one of them is the reverse of the other. For example, pots and stop are a reverse pair.

The words in a reverse pair must be different, so gag and gag are not a reverse pair.

Make a list of all reverse pairs in word_list. Each pair of words should appear only once, so if ('tons', 'snot') is in the list, ('snot', 'tons') should not be.

BONUS QUESTION JUST FOR FUN: What is the longest reverse pair in this word list?