CSCI 150 - Foundations of Computer Science

Fall 2013

Programming Exercises: Comprehensions

For all of these exercises, use list (or dictionary) comprehensions.

Write a function called multBy(nums, n) (where nums is a list of numbers and n is a number) that returns a new list containing each number from nums multiplied by n.
```
>>> multBy([5, -3, 2], 3)
[15, -9, 6]
```
Write a function called lowerCase(words) (where words is a list of strings) that returns a new list containing each word from the original list converted to lower case.
```
>>> lowerCase(['GIANT', 'College', 'comPuter'])
['giant', 'college', 'computer']
```
Write a function called initialVowel(words) (where words is a list of strings) that returns a new list of all of those strings that start with a vowel.
```
>>> initialVowel(['any', 'every', 'none', 'some', 'About'])
['any', 'every', 'About']
```
Write a function called pastWords(words) (where words is a list of strings) that returns a new list of all of those strings that end with "ed".
```
>>> pastWords(['helped', 'educate', 'replaced', 'asked', 'talking'])
['helped', 'replaced', 'asked']
```
Write a function called workable(words) (where words is a list of strings) that returns a new list of all of those strings that contain the substring "work".
```
>>> workable(['spark', 'rework', 'target', 'working', 'unworkable'])
['rework', 'working', 'unworkable']
```

Write a function called longPhrases(phrases, n) (where phrases is a list of strings) that returns a new list of all of those strings that contain n or more distinct words.

>>> longPhrases(['Star Wars', 'The Empire Strikes Back', 'Raiders of the Lost Ark', 'Titanic', 'The Terminator'], 4)
['The Empire Strikes Back', 'Raiders of the Lost Ark']

Write a function called squares(nums) (where nums is a list of numbers) that returns a dictionary mapping each number to its square.
```
>>> squares([5, 2, -3])
{2: 4, 5: 25, -3: 9}
```