IvanFrecia

class Book():
    def __init__(self, title, author):
        self.title = title
        self.author = author
    def __str__(self):
        return '"{}" by {}'.format(self.title, self.author)


class PaperBook(Book):
    def __init__(self, title, author, numPages):

IvanFrecia

# 1) Define a class called Bike that accepts a string and a float as input, and assigns those inputs respectively 
# to two instance variables, color and price. Assign to the variable testOne an instance of Bike whose color is blue 
# and whose price is 89.99. Assign to the variable testTwo an instance of Bike whose color is purple and 
# whose price is 25.0.

# Solution:

class Bike:
    
    def __init__(self, color, price):

IvanFrecia

class Point:
    """ Point class for representing and manipulating x,y coordinates. """

    printed_rep = "*"

    def __init__(self, initX, initY):

        self.x = initX
        self.y = initY

IvanFrecia

L = ["Cherry", "Apple", "Blueberry"]

print(sorted(L, key=len))
#alternative form using lambda, if you find that easier to understand
print(sorted(L, key= lambda x: len(x)))

# Output:
# ['Apple', 'Cherry', 'Blueberry']
# ['Apple', 'Cherry', 'Blueberry']

IvanFrecia

# Suppose you have a point object and wish to find the midpoint halfway between it and some other target point. 
# We would like to write a method, let’s call it halfway, which takes another Point as a parameter and returns 
# the Point that is halfway between the point and the target point it accepts as input.

class Point:

    def __init__(self, initX, initY):

        self.x = initX
        self.y = initY

IvanFrecia

# 1) Write code to assign to the variable map_testing all the elements in lst_check while adding the string “Fruit: ” 
# to the beginning of each element using mapping.

lst_check = ['plums', 'watermelon', 'kiwi', 'strawberries', 'blueberries', 'peaches', 'apples', 'mangos', 'papaya']

map_testing = map(lambda str: "Fruit: " + str, lst_check)
print(map_testing)

# Ouput: ['Fruit: plums', 'Fruit: watermelon', 'Fruit: kiwi', 'Fruit: strawberries', 'Fruit: blueberries', 'Fruit: peaches', 'Fruit: apples', 'Fruit: mangos', 'Fruit: papaya']

IvanFrecia

# The zip function takes multiple lists and turns them into a list of tuples 
# (actually, an iterator, but they work like lists for most practical purposes), 
# pairing up all the first items as one tuple, all the second items as a tuple, and so on. 
# Then we can iterate through those tuples, and perform some operation on all the first items, 
# all the second items, and so on.

L1 = [3, 4, 5]
L2 = [1, 2, 3]
L4 = list(zip(L1, L2))
print(L4)

IvanFrecia

# Python provides an alternative way to do map and filter operations, called a list comprehension. 
# Many programmers find them easier to understand and write. List comprehensions are concise ways to 
# create lists from other lists. The general syntax is:

# [<transformer_expression> for <loop_var> in <sequence> if <filtration_expression>]

things = [2, 5, 9]
yourlist = [value * 2 for value in things] # t[<trans.exp is "value * 2"> <item variable is "value"> <sequence is "things">]
print(yourlist)

IvanFrecia

# Now consider another common pattern: going through a list and keeping only those items that meet certain criteria. This is called a filter.

# Again, this pattern of computation is so common that Python offers a more compact and general way to do it, 
# the filter function. filter takes two arguments, a function and a sequence. The function takes one item
# and return True if the item should. It is automatically called for each item in the sequence. You don’t 
# have to initialize an accumulator or iterate with a for loop.

def keep_evens(nums):
    new_seq = filter(lambda num: num % 2 == 0, nums)
    return list(new_seq)

IvanFrecia

# 1) Using map, create a list assigned to the variable greeting_doubled that doubles each element in the 
# list lst.

lst = [["hi", "bye"], "hello", "goodbye", [9, 2], 4]

greeting_doubled = map((lambda a_list: a_list * 2), lst)
print(greeting_doubled)

# Output:
# [['hi', 'bye', 'hi', 'bye'], 'hellohello', 'goodbyegoodbye', [9, 2, 9, 2], 8]