Homework 4 | C88C Spring 2023
Homework 4
Due at 11:59:59 pm on Thursday, 2/23/2023.
Instructions
Download hw04.zip.
Inside the archive, you will find starter files for the questions in this homework,
along with a copy of the OK autograder.
Submission: When you are done, submit with python3 ok –submit. You may submit more than once before the deadline; only the final submission will be scored. Check that you have successfully submitted your code on okpy.org.
Readings: This homework relies on following references:
Section 1.6
Question 1: Operation-inator
Dr. Doofenshmirtz is making a secret evil device that creates functions that do basic arithmetic operations using lambda functions. The operation-inator takes in an operation_string and returns a function that does that specific operation. The strings map to the functions like so:
“self” -> function that returns the input
“add one” -> function that adds one to the input
“multiply together” -> Takes in two inputs and returns them multiplied
“zero to self” -> takes in a positive integer and returns a list that counts up by ones from zero (inclusive) to the input (exclusive)
Help the good doctor implement his operation-inator by filling in the blanks with lambda functions.
See the doctests for more details.
def operation_inator(operation_string):
>>> identity = operation_inator(‘self’)
>>> identity(5)
>>> identity(6)
>>> add_one = operation_inator(‘add one’)
>>> add_one(2)
>>> add_one(3)
>>> mul_together = operation_inator(‘multiply together’)
>>> mul_together(0, 1)
>>> mul_together(3, 2)
>>> zero_to_self = operation_inator(‘zero to self’)
>>> zero_to_self(3)
>>> zero_to_self(1)
“*** YOUR CODE HERE ***”
Use OK to test your code:
python3 ok -q operation_inator
Question 2: Higher Order Lambdas
Return a lambda function that takes in a multiplier (the multiplier is a number) and returns a
lambda function that will take in another number and will return the new input multiplied by the multiplier.
def higher_order_lambdas():
Return a lambda function that takes in a multiplier and returns a lambda function that given an input will
return the input multiplied by the multiplier
>>> hol = higher_order_lambdas()
>>> doubles = hol(2)
>>> doubles(3)
>>> hol = higher_order_lambdas()
>>> triples = hol(3)
>>> triples(4)
“*** YOUR CODE HERE ***”
Use OK to test your code:
python3 ok -q higher_order_lambdas
Question 3: Lambdas and Currying
We can transform multiple-argument functions into a chain of
single-argument, higher order functions by taking advantage of lambda
expressions. This is useful when dealing with functions that take only
single-argument functions. We will see some examples of these later
Write a function lambda_curry2 that will curry any two argument
function f2 using lambdas. See the doctest if you’re not sure what this
def lambda_curry2(f2):
Returns a Curried version of a two argument function func.
>>> from operator import add
>>> x = lambda_curry2(add)
>>> y = x(3)
“*** YOUR CODE HERE ***”
Use OK to test your code:
python3 ok -q lambda_curry2
Dictionaries
Question 4: Replace All
Given a dictionary d, return a new dictionary where all occurences of x as a value (not a key) is replaced with y.
def replace_all(d, x, y):
>>> d = {‘foo’: 2, ‘bar’: 3, ‘garply’: 3, ‘xyzzy’: 99}
>>> e = replace_all(d, 3, ‘poof’)
>>> e == {‘foo’: 2, ‘bar’: ‘poof’, ‘garply’: ‘poof’, ‘xyzzy’: 99}
“*** YOUR CODE HERE ***”
Use OK to test your code:
python3 ok -q replace_all
Question 5: Merge Dictionaries
Implement the function merge_dict. The merge_dict function merges two dictionaries with the same keys together
by adding up their values for the corresponding keys and returning the resulting dictionary.
def merge_dict(dict1, dict2):
“””Returns a dictionary that is the result of two dictionaries being merged together.
Dictionaries are merged by adding up their values. You can assume that the same keys
appear in both dictionaries.
>>> data8 = {“midterms”:1, “projects”:3}
>>> data100 = {“midterms”:2, “projects”:3}
>>> combined_exams = merge_dict(data8, data100)
>>> combined_exams
{‘midterms’: 3, ‘projects’: 6}
>>> sunday_orders = {“pizza”: 3, “hot dogs”: 2, “fries”: 5}
>>> monday_orders = {“pizza”: 1, “hot dogs”: 1, “fries”: 8}
>>> combined_orders = merge_dict(sunday_orders, monday_orders)
>>> combined_orders
{‘pizza’: 4, ‘hot dogs’: 3, ‘fries’: 13}
“*** YOUR CODE HERE ***”
Use OK to test your code:
python3 ok -q merge_dict
Make sure to submit this assignment by running:
python3 ok –submit
Question 1: Operation-inator
Question 2: Higher Order Lambdas
Question 3: Lambdas and Currying
Dictionaries
Question 4: Replace All
Question 5: Merge Dictionaries