Practice: Functions

Practice: Functions#

In this set of practice problems, it’s all about functions - how to execute them, how to write our own functions, and how to debug functions.

As for all practice sections, each question will include a handful of assert statements. After you write and execute the code to each question, each assert should “pass silently” (meaning: should give no output upon execution) indicating that you are on the right track. After you’ve written your code and run the asserts, you can always check your answers, as the answers to these questions are included in the “Answers” chapter of this book.

Function Execution#

Function Execution 1. The function square_default has been provided for you. After defining the function, execute (use) this function to create the following variables under the specified conditions:

square_default | execute the square_all function using the default parameter such that the output will carry out the function on a list of input values containing the integers 2, 3, and 4.
power_three | Use the same input values as above, but this time, use the square_all function provided to raise all input values to the power 3
out_4 | Execute the square_all function such that out_4 will store a list with 4 values, each of which is the integer 4.

Function provided:

def square_all(collection, power=2):
    
    square_list = []
    for val in collection:
        square_list.append(val**power)
    
    return square_list

Checks you can use to see if you’re on the right track:

assert  square_default == [4,9,16]
assert power_three  == [8, 27, 64]
assert out_4  == [4,4,4,4]

Function Execution Q2. The function convert_temp has been provided for you. After understanding the code in the function, define the function. Then, execute (use) this function to create the following variables under the specified conditions:

tempA | execute the convert_temp function to convert the temperature 95 degrees Fahrenheit into degrees Celsius
tempB | execute convert_temp to convert the temperature 17 degrees Celsius into degrees Fahrenheit

Provided function:

def convert_temp(temp, input_unit='F'):
    
    if input_unit == 'F':
        out_temp = (temp - 32) * 5/9
    elif input_unit == 'C':
        out_temp = (temp * 9/5) + 32
    else:
        print("Please specify either 'F' or 'C' for input_unit")
        
    return out_temp

Checks you can use to see if you’re on the right track:

assert tempA == 35.0
assert tempB == 62.6

Function Execution Q3 The function court_jester_jokes that has been provided for you. After understanding the code in the function, run the cell below (to define this function). Then, execute (use) this function to create the following variables under the specified conditions:

joke_random | execute the court_jester_jokes function to return a joke at random
joke_nonrandom | execute court_jester_jokes to return the second joke in joke_list

Function provided:

import random

def court_jester_jokes(random_joke=True):
    joke_list = ['A clown held the door open for me yesterday. I thought it was a nice jester',
                 'How does the court jester address the King of Ducks? Mal’Lard',
                 'What did the court jester call the balding crown prince? The Heir Apparent with no Hair Apparent',
                 'What do you call a joke made by using sign language? A jester']
    
    if random_joke:
        out_joke = random.choice(joke_list)
    else:
        out_joke = joke_list[1]

    return out_joke

jokes = ['A clown held the door open for me yesterday. I thought it was a nice jester',
         'How does the court jester address the King of Ducks? Mal’Lard',
         'What did the court jester call the balding crown prince? The Heir Apparent with no Hair Apparent',
         'What do you call a joke made by using sign language? A jester']
assert joke_random in jokes
assert joke_nonrandom == 'How does the court jester address the King of Ducks? Mal’Lard'

User-Designed Functions (UDFs)#

UDFs Q1 Write a function provide_info that takes three parameters: name, year, and school. Set the default value for school to be ‘UCSD’.

This function should return the string “Hi! I’m name. I am a year at school.” (where the variable names are replaced by the values input to the function upon execution).

For example, one possible execution of this function could return “Hi! I’m Shannon. I am a sophomore at UCSD.”

Note: Be sure punctuation and spacing match that specified in the instructions.

Checks you can use to see if you’re on the right track:

assert provide_info(name='Taylor', year='junior', school='UCLA') == "Hi! I'm Taylor. I am a junior at UCLA." 
assert provide_info(name='Shannon', year='junior') == "Hi! I'm Shannon. I am a junior at UCSD."

UDFs Q2. Write a function count_int that will take a tuple or list as the input and count the number (count) of integer values in that tuple/list, returning this value from the function.

For example, if 3 of the values in the input list were integers, the function would return 3.

Note: You can assume the input to this function will be a tuple or list and do not need to write code to check whether or not this is true.

Checks you can use to see if you’re on the right track:

assert count_int(['string']) == 0
assert count_int((1,2,3,4,5,'string',4.4)) == 5

UDFs Q3. Define a function modify_string with a single parameter input_string. If any of the characters in the input_string to the function are keys in the dictionary new_language below, use that key’s value in that letter’s place. If the letter is not in new_language, the resulting string should store the same character.

For example, if my_name stored ‘Shannon’, the output from this function would store ‘Shӓnnðn’ (the a and the o have the modified character from new_language)

Variable provided:

new_language = {'a': 'ӓ',
                'e' : 'ɚ',
                'i' : '¡',
                'o' : 'ð', 
                'u' : 'û',
                'A' : 'Ӓ', 
                'E' : 'ɛ', 
                'O' : 'Ó', 
                'U' : 'Ü'}

Checks you can use to see if you’re on the right track:

assert modify_string('AaEe') == 'Ӓӓɛɚ'
assert modify_string('BbCc') == 'BbCc'
assert modify_string('Taylor') == 'Tӓylðr'
assert modify_string('AaBbCcEe') == 'ӒӓBbCcɛɚ'

UDFs Q4 Write a function calculate_points that has a single input parameter: hand. hand can be assumed to be a list of string values, where each string corresponds to a value in a deck of cards (2-10, J, Q, K, or A)

This function should calculate the total number of “pointer” cars in your hand, where a “pointer” is either a 10, J, Q, K, or A. Each “pointer” is worth one point. All other cards are worth zero points. The function should return the total number of points in the hand as an integer.

For example, if your hand input was:

['J', '10', '2', '5', 'K']

executing the calculate_points() function with the above list as the input to the hand parameter, the function would return the integer 3 (one point each for the 'J', '10', and 'K'.

If there are no pointers in the input hand, the function should return 0.

Checks you can use to see if you’re on the right track:

assert calculate_points(['2', '7', '9']) == 0
assert calculate_points(['K']) == 1
assert calculate_points(['J', '10', '2', '5', 'K']) == 3

UDFs Q5. Recently, the company you work at (‘cogs co.’) realized that too many employees have problematic usernames. You’re going to write a function (change_username()) that takes a single parameter username as input.

This function will check if the username meets the following specifications:

contains more than four characters
includes only letters (A-Z; a-z) and/or numbers (0-9); in other words: is alphanumeric
does NOT include the string ‘cogs’

If the username meets the above specifications, the function will return False (indicating the username does not have to be changed. If any one of the above specifications is not met, the function will return True (indicating that the username does not meet at least one of the above specifications).

For example, change_username(username='cogs') would return True because it does not contain more than four letters and because it includes the string 'cogs' in its name, while change_username(username='Shannon') would return False, as this meets all three specifications above.

Checks you can use to see if you’re on the right track:

assert change_username('aaaaa') == False
assert change_username('aaaa') == True
assert change_username('AAAAA') == False
assert change_username('12345') == False
assert change_username('cogs123') == Trueb

UDFs Q6. Write a function that, given a salary as input, will return how much of that person’s salary is going toward taxes.

To accomplish this, write a function to_taxes() that takes two parameters as input: salary and tax_brackets. The default value for the tax_brackets parameter should be the default_brackets dictionary provided below. Then, use code constructs discussed in class to accomplish the above goal.

Note that the dictionary default_brackets provided will have to be used to accomplish this goal. The keys in default_brackets are the proportion of an individual’s salary that will go toward taxes if their salary is within the range in a given key’s value (tuple). For example, an individual who makes $10,000 would contribute 12% of their salary in taxes, given the information in tax_brackets (specifically becasue 10000 falls between 9876 and 40125).

Accordingly, to_taxes(salary=10000) should return 1200.0 (which corresponds to 12% of the input $10,000 salary).

Variable provided:

default_brackets = {0.10 : (0, 9875),
                    0.12 : (9876, 40125),
                    0.22 : (40126, 85525),
                    0.24 : (85526, 163300),
                    0.32 : (163301, 207350),
                    0.35 : (207351, 518400)
                   }

Checks you can use to see if you’re on the right track:

assert to_taxes(10000) == 1200.0
assert to_taxes(207355) == 72574.25
assert to_taxes(40126) == 8827.72
assert to_taxes(85525) == 18815.5
assert to_taxes(100, tax_brackets={0.5: (0,1000)}) == 50.0

Debugging#

Debugging Q1 The function count_consonants is provided, but it is not operating as anticipated.

count_consonants is supposed to take a string as input and count the number of each consonant in the input_string (input parameter), storing the output in a dictionary where the key is the consonant and the value is the number of times it appears in the input.

Note that we want capitalization to be considered such that the capital and lower case letters are counted together, and the lower case letter is used as the key (i.e. ‘A’ and ‘a’ would both be counted under the key ‘a’)

Specifically, if the input_string were “Mohammed”, the function ould return: {'m': 3, 'h': 1, 'd': 1}

Debug, edit, and test the function provided so that it accomplishes the intended goal.

Function provided:

def count_consonants():
    out = {}
    vowels = ['a', 'e', 'i', 'o', 'u']
    
    for char in input_string:
        
        if char not in vowels:
            if char not in out:
                out[char] = 1

Checks you can use to see if you’re on the right track:

assert count_consonants('Taylor') == {'t': 1, 'y': 1, 'l': 1, 'r': 1}
assert count_consonants('AaBbCc') == {'b': 2, 'c': 2}

Debugging Q2 The provided new_encrypt function is not operating as anticipated.

new_encrypt is supposed to take a string as input and return the reverse alphabetical string as output, meaning, given a character, return the capitalized character in the reverse position within the alphabet.

For example, if the input character is ‘B’ or ‘b’, the function would store ‘Y’ in the output string. If the character is ‘A’ or ‘a’, the function would store ‘Z’. (and vice versa: the input ‘Z’ or ‘z’ would store ‘A’).

Specifically, if the input_string were “ABc”, the function would return: ‘ZYX’

Debug, edit, and test the function provided below so that it accomplishes the intended goal.

Provided function:

def new_encrypt():
    alpha = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    reverse_alpha = 'ZYXWVUTSRQPONMLKJIHGFEDCBA'

    for char in input_string:
        if char in alpha:
            position = alpha.find(char)
            output_string += reverse_alpha[position]
        else:
            output_string = None
            break

Checks you can use to see if you’re on the right track:

assert new_encrypt('mohammed') == 'NLSZNNVW'
assert new_encrypt(input_string='ABC') == 'ZYX'

Debugging Q3 The not-totally-functioning growth_rate() function is provided for you. The goal of this function, is given two population inputs: last_year, this_year, the function should return the population growth rate for that country.

For example, in 2020, China’s population was 1439323776. This year, its population is 1444216107.

Population growth rate is calculated by taking the difference between this year’s population minus last year’s population, dividng that difference by last year’s population, and multiplying the entire quantity by 100.

Given China’s numbers above and this calculation, we know that this function should return 0.34…but it’s not at this point.

Consider the function currently and then debug (you can edit the code provided directly or copy and paste below so you still have the original if needed) to accomplish the task specified above.

Note: Do not change the name of the function (growth_rate), and the parameter names provided in the instructions (last_year, this_year) must be used.

Function provided:

def growth_rate(self, this_year, last_year):
    self.this_year - self.last_year/self.last_year * 100

assert 0 < growth_rate(last_year=331002651,
                       this_year=332915073) > 1

Practice: Functions

Contents

Practice: Functions#

Function Execution#

User-Designed Functions (UDFs)#

Debugging#