CS-UY 1114代写、代做Python、Python语言程序调试

日期：2018-12-03 10:50

Homework 9:

Dictionaries

CS-UY 1114 NYU Tandon

Submit your solution to all problems in a single Python file named YourNetID_hw9.py.

Problem 1

Consider the following dict, which provides a mapping of commonly misspelled words to

their correct spelling. Type the dictionary, exactly as given, into your file.

respellings = {

"teh": "the",

"relevent": "relevant",

"lite": "light",

"lol": "haha",

}

Write a function respell, which takes a str argument and returns a string with the

spelling corrected according to the content of the dict. Your solution must reference the

respellings dictionary as its source of information. It can be used like this:

>>> respell("I ate teh whole thing lol")

'I ate the whole thing haha'

Hint: use the split function to convert the input string into a list of words. Then use

you can use the join function to convert a (corrected) list of words back into a string.

Hint: iterate over the list of words, replacing the current word if necessary and appending

it to an accumulator.

Hint: use the in operator to determine if a particular word is a key in the dict. Use

respellings[word] to get the value associated with word from the dict. If the word

isn’t in respellings, then the word is added to the output unchanged.

Problem 2

The position of a word in a string is the index of that word in list of words comprising

the string. For example:

It

was

φ

the

best

of

Κ

times

Θ

it

was

the

worst

ν

of

φ

times

φφ

Write a function called “word_positions” with signature str -> dict (str, list (int)).

It should return a dictionary whose keys are the words that occur in the argument string,

and where the value associated to a given key is the list of positions at which that word

occurs.

For example:

1

>>> word_positions ('It was the best of times it was the worst of times ')

{'It': [0], 'was ': [1, 7], 'the ': [2, 8], 'best ': [3], 'of': [4, 10],

'times ': [5, 11], 'it': [6], 'worst ': [9]}

Hint: for the purposes of this problem you may assume that the string does not include

any punctuation. Also, you do not need to do any case normalization, so in this problem

'It' and 'it' are considered different words. To obtain the list of words in a string, call

the split function:

>>> 'welcome to the future '.split()

['welcome ', 'to', 'the', 'future ']

>>> "now's the time".split ()

["now's", 'the', 'time ']

Problem 3

Write a function called “commonest” that takes a dictionary like the one produced by

word_positions as an argument and returns a key whose value list is the longest:

>>> word_positions("He thought a thought he'd never thought before")

{'He':[0], 'thought ':[1, 3, 6], 'a':[2], "he'd":[4], 'never ':[5], 'before ':[7]}

>>> commonest(word_positions("He thought a thought he'd never thought before"))

'thought '

If the dictionary is empty, then your function should return the empty string.

If there is a tie for the word with the longest list of positions, then your function

may return any one of the most common words.

Hint: iterate over the dictionary and compare the length of the list of positions for each

word to the length of the longest list seen thus far. Each time you find a new longest list,

you will need to update both the commonest word its number of occurrences.