"""
PRACTICE Exam 2, practice_problem 1.
Authors: David Mutchler, Sana Ebrahimi, Mohammed Noureddine, Vibha Alangar,
Matt Boutell, Dave Fisher, Mark Hays, their colleagues, and
PUT_YOUR_NAME_HERE.
""" # TODO: 1. PUT YOUR NAME IN THE ABOVE LINE.
###############################################################################
# Students:
#
# These problems have DIFFICULTY and TIME ratings:
# DIFFICULTY rating: 1 to 10, where:
# 1 is very easy
# 3 is an "easy" Exam 2 question.
# 5 is a "typical" Exam 2 question.
# 7 is a "hard" Exam 2 question.
# 10 is an EXTREMELY hard problem (too hard for an Exam 2 question)
#
# TIME ratings: A ROUGH estimate of the number of minutes that we
# would expect a well-prepared student to take on the problem.
#
# IMPORTANT: For ALL the problems in this module,
# if you reach the time estimate and are NOT close to a solution,
# STOP working on that problem and ASK YOUR INSTRUCTOR FOR HELP
# on it, in class or via Piazza.
###############################################################################
import math
import time
from numbers import Number
import testing_helper
###############################################################################
# TODO: 2. READ the Point class defined below.
# Note especially its methods:
# clone
# distance_from
# For full credit, you must use (call) these as appropriate in your code.
# After you UNDERSTAND the SPECIFICATIONS of the methods and instance
# variables (but not necessarily all of the code) of the Point class,
# change the above _TODO_ to DONE.
###############################################################################
class Point(object):
""" Represents a point in 2-dimensional space. """
def __init__(self, x, y):
""" Sets instance variables x and y to the given coordinates. """
self.x = x
self.y = y
def __repr__(self):
"""
Returns a string representation of this Point.
For each coordinate (x and y), the representation:
- Uses no decimal points if the number is close to an integer,
- Else it uses 2 decimal places after the decimal point.
Examples:
Point(10, 3.14)
Point(3.01, 2.99)
"""
decimal_places = 2 # Use 2 places after the decimal point
formats = []
numbers = []
for coordinate in (self.x, self.y):
if abs(coordinate - round(coordinate)) < (10 ** -decimal_places):
# Treat it as an integer:
formats.append('{}')
numbers.append(round(coordinate))
else:
# Treat it as a float to decimal_places decimal places:
formats.append('{:.' + str(decimal_places) + 'f}')
numbers.append(round(coordinate, decimal_places))
format_string = 'Point(' + formats[0] + ', ' + formats[1] + ')'
return format_string.format(numbers[0], numbers[1])
def __eq__(self, p2):
"""
Defines == for Points: a == b is equivalent to a.__eq__(b).
Treats two numbers as "equal" if they are within 6 decimal
places of each other for both x and y coordinates.
"""
return (round(self.x, 6) == round(p2.x, 6) and
round(self.y, 6) == round(p2.y, 6))
def clone(self):
""" Returns a Point whose x and y are the same as this Point's."""
return Point(self.x, self.y)
def distance_from(self, p2):
""" Returns the distance this Point is from the given Point. """
dx_squared = (self.x - p2.x) ** 2
dy_squared = (self.y - p2.y) ** 2
return math.sqrt(dx_squared + dy_squared)
###############################################################################
# The main function and the TODOs for you are after this:
###############################################################################
def main():
""" Calls the TEST functions in this module. """
# -------------------------------------------------------------------------
# Uncomment the following calls to the testing functions one at a time
# as you work the problems.
# -------------------------------------------------------------------------
print()
print('Un-comment the calls in MAIN one by one')
print(' to run the testing code as you complete the TODOs.')
# run_test_init()
# run_test_area()
# run_test_bigger_triangle()
# run_test_shrink_or_expand()
# run_test_return_doubled_triangle()
# run_test_get_largest_area()
###############################################################################
# The Triangle class (and its methods) begins here.
###############################################################################
class Triangle(object):
""" Represents a triangle in 2-dimensional space. """
# IMPORTANT: Be CERTAIN you understand the Example in the spec below.
def __init__(self, a, b, c):
"""
What comes in:
-- self and three Point objects
where the three Point objects are to be the initial points
of this Triangle.
What goes out: Nothing (i.e., None).
Side effects:
Sets instance variables:
self.a
self.b
self.c
to CLONES of the three Point objects a, b, and c.
Also, initializes other instance variables as needed
by other Triangle methods.
Example: This __init__ method runs when one constructs
a Triangle. So the fourth of the following statements
invokes the __init__ method of this Line class:
p1 = Point(30, 17)
p2 = Point(50, 80)
p3 = Point(35, 15)
triangle = Triangle(p1, p2, p3) # Causes __init__ to run
print(triangle.a) # Should print Point(30, 17)
print(triangle.b) # Should print Point(50, 80)
print(triangle.c) # Should print Point(35, 15)
print(triangle.a == p1) # Should print True
print(triangle.a is p1) # Should print False
Type hints:
:type a: Point
:type b: Point
:type c: Point
"""
# ---------------------------------------------------------------------
# TODO: 3.
# a. READ the above specification, including the Example.
# ** ASK QUESTIONS AS NEEDED. **
# ** Be sure you understand it, ESPECIALLY the Example.
# b. Implement and test this method.
# The tests are already written (below).
# They include the Example in the above doc-string.
# ---------------------------------------------------------------------
# IMPORTANT: Read the HINT in the specification below.
def area(self):
"""
What comes in:
-- self
What goes out: Returns the area of this Triangle.
Side effects: None.
HINT: Recall Heron's formula for the area of a triangle:
Area = square root of (S
* (S - length of side 1)
* (S - length of side 2)
* (S - length of side 3))
where S = (1/2) * (length of perimeter of the triangle)
For example: if the triangle has endpoints:
a = Point(15, 35)
b = Point(15, 50)
c = Point(35, 45)
then one can compute (** using the Point distance_from method **) that:
the length of the side from a to b is (about): 15
the length of the side from b to c is (about): 20.6
the length of the side from c to a is (about): 22.4
and hence S is (about) (1/2) * (15 + 20.6 + 22.4),
which is about 28.99
and so the area of the Triangle is (per the formula):
150.0
Type hints:
:rtype: float
"""
# ---------------------------------------------------------------------
# TODO: 4.
# a. READ the above specification, including the Example AND HINT!
# __
# ************* READ THE HINT!!!!!!!!! *************
# __
# ** ASK QUESTIONS AS NEEDED. **
# ** Be sure you understand it, ESPECIALLY the Example.
# b. Implement and test this method.
# The tests are already written (below).
# They include the Example in the above doc-string.
# ---------------------------------------------------------------------
# IMPORTANT: CALL the area method in your solution to the following.
def bigger_triangle(self, triangle2):
"""
What comes in:
-- self
-- another Triangle object
What goes out: returns True if this Triangle has a larger area than
the given Triangle (triangle2). Returns False otherwise.
Side effects: None.
Type hints:
:type: triangle2: Triangle
:rtype: bool
"""
# ---------------------------------------------------------------------
# TODO: 5.
# a. READ the above specification, including the Example.
# ** ASK QUESTIONS AS NEEDED. **
# ** Be sure you understand it, ESPECIALLY the Example.
# b. Implement and test this method.
# The tests are already written (below).
# They include the Example in the above doc-string.
# ---------------------------------------------------------------------
# IMPORTANT: In the function below, do NOT return a Triangle. Mutate it.
def shrink_or_expand(self, f):
"""
What comes in:
-- self
-- a positive number f
What goes out: Nothing.
Side effects: MUTATES this Triangle object by multiplying
the x and y coordinates of each of this Triangle's three points
by the given number f.
Type hints:
:type: f: float
"""
# ---------------------------------------------------------------------
# TODO: 6.
# a. READ the above specification, including the Example.
# ** ASK QUESTIONS AS NEEDED. **
# ** Be sure you understand it, ESPECIALLY the Example.
# b. Implement and test this method.
# The tests are already written (below).
# They include the Example in the above doc-string.
# ---------------------------------------------------------------------
def return_doubled_triangle(self):
"""
What comes in:
-- self
What goes out:
-- Return a new Triangle object that is the same as this Triangle
object, except that the x and y coordinates of its a, b, and c
endpoints are each TWICE the values of this Triangle's a, b and c.
Side effects: None.
Type hints:
:rtype: Triangle:
"""
# -------------------------------------------------------------------------
# TODO: 7.
# a. READ the above specification, including the Example.
# ** ASK QUESTIONS AS NEEDED. **
# ** Be sure you understand it, ESPECIALLY the Example.
# b. Implement and test this method.
# The tests are already written (below).
# They include the Example in the above doc-string.
# -------------------------------------------------------------------------
def get_largest_area(self):
"""
What comes in:
-- self
What goes out:
-- Returns the area of the Triangle when it was the largest
during any shrink_or_expand operations.
Returns the initial area of the Triangle if there have
been no shrink_or_expand operations so far.
Side effects: None.
Type hints:
:rtype: float:
"""
# ---------------------------------------------------------------------
# TODO: 8.
# a. READ the above specification, including the Example.
# ** ASK QUESTIONS AS NEEDED. **
# ** Be sure you understand it, ESPECIALLY the Example.
# b. Implement and test this method.
# The tests are already written (below).
# They include the Example in the above doc-string.
# ---------------------------------------------------------------------
###############################################################################
# The TEST functions for the Triangle class begin here.
###############################################################################
def run_test_init():
""" Tests the __init__ method of the Triangle class. """
print()
print('-----------------------------------------------------------')
print('Testing the __init__ method of the Triangle class.')
print('-----------------------------------------------------------')
# Test 1
print('\nTest 1:')
p1 = Point(0, 0)
p2 = Point(5, 2)
p3 = Point(3, 6)
t1 = Triangle(p1, p2, p3)
expected_a = Point(0, 0)
expected_b = Point(5, 2)
expected_c = Point(3, 6)
run_test_instance_variables(t1, expected_a, expected_b, expected_c)
if (p1 is t1.a) or (p2 is t1.b) or (p3 is t1.c):
print_failure_message(
'\nFAILED CLONING: You failed to CLONE the arguments.\n'
+ 'See your instructor for help.\n')
# Test 2
print('\nTest 2:')
p1 = Point(10, 10)
p2 = Point(15, 34)
p3 = Point(45, 100)
t2 = Triangle(p1, p2, p3)
expected_a = Point(10, 10)
expected_b = Point(15, 34)
expected_c = Point(45, 100)
run_test_instance_variables(t2, expected_a, expected_b, expected_c)
if (p1 is t1.a) or (p2 is t1.b) or (p3 is t1.c):
print_failure_message(
'\nFAILED CLONING: You failed to CLONE the arguments.\n'
+ 'See your instructor for help.\n')
def run_test_area():
""" Tests the area method of the Triangle class. """
print()
print('-----------------------------------------------------------')
print('Testing the area method of the Triangle class.')
print('-----------------------------------------------------------')
p1 = Point(15, 35)
p2 = Point(15, 50)
p3 = Point(35, 45)
t1 = Triangle(p1, p2, p3)
print()
print('Expected for area:', 150.0)
print('Actual: ', t1.area())
print_result_of_test(150.0, t1.area())
p4 = Point(25, 40)
p5 = Point(15, 50)
p6 = Point(35, 45)
t2 = Triangle(p4, p5, p6)
print()
print('Expected for area:', 75.0)
print('Actual: ', t2.area())
print_result_of_test(75.0, t2.area())
p7 = Point(15, 20)
p8 = Point(25, 10)
p9 = Point(35, 20)
t3 = Triangle(p7, p8, p9)
print()
print('Expected for area:', 100.0)
print('Actual: ', t3.area())
print_result_of_test(100.0, t3.area())
def run_test_bigger_triangle():
""" Tests the bigger_triangle method of the Triangle class. """
print()
print('-----------------------------------------------------------')
print('Testing the bigger_triangle method of the Triangle class.')
print('-----------------------------------------------------------')
p1 = Point(15, 35)
p2 = Point(15, 50)
p3 = Point(35, 45)
t1 = Triangle(p1, p2, p3)
p4 = Point(40, 45)
t2 = Triangle(p1, p2, p4)
print()
print('Expected for bigger_triangle:', True)
print(' Actual:', t2.bigger_triangle(t1))
print_result_of_test(True, t2.bigger_triangle(t1))
print()
print('Expected for bigger_triangle:', False)
print(' Actual:', t1.bigger_triangle(t2))
print_result_of_test(False, t1.bigger_triangle(t2))
print()
print('Expected for bigger_triangle:', False)
print(' Actual:', t1.bigger_triangle(t1))
print_result_of_test(False, t1.bigger_triangle(t1))
p5 = Point(15, 20)
p6 = Point(25, 10)
p7 = Point(35, 20)
t3 = Triangle(p5, p6, p7)
p8 = Point(25, 40)
p9 = Point(15, 50)
p10 = Point(35, 45)
t4 = Triangle(p8, p9, p10)
print()
print('Expected for bigger_triangle:', False)
print(' Actual:', t4.bigger_triangle(t3))
print_result_of_test(False, t4.bigger_triangle(t3))
print()
print('Expected for bigger_triangle:', True)
print(' Actual:', t3.bigger_triangle(t4))
print_result_of_test(True, t3.bigger_triangle(t4))
print()
print('Expected for bigger_triangle:', True)
print(' Actual:', t1.bigger_triangle(t3))
print_result_of_test(True, t1.bigger_triangle(t3))
print()
print('Expected for bigger_triangle:', True)
print(' Actual:', t1.bigger_triangle(t4))
print_result_of_test(True, t1.bigger_triangle(t4))
def run_test_shrink_or_expand():
""" Tests the shrink_or_expand method of the Triangle class. """
print()
print('-----------------------------------------------------------')
print('Testing the shrink_or_expand method of the Triangle class.')
print('-----------------------------------------------------------')
# Test 1
print('\nTest 1:')
p1 = Point(10, 20)
p2 = Point(18, 26)
p3 = Point(30, 10)
t1 = Triangle(p1, p2, p3)
t1.shrink_or_expand(0.5)
expected_a = Point(5, 10)
expected_b = Point(9, 13)
expected_c = Point(15, 5)
run_test_instance_variables(t1, expected_a, expected_b, expected_c)
p1 = Point(20, 50)
p2 = Point(10, 30)
p3 = Point(5, 60)
t2 = Triangle(p1, p2, p3)
t2.shrink_or_expand(3)
expected_a = Point(60, 150)
expected_b = Point(30, 90)
expected_c = Point(15, 180)
run_test_instance_variables(t2, expected_a, expected_b, expected_c)
def run_test_return_doubled_triangle():
""" Tests the return_doubled_triangle method of the Triangle class. """
print()
print('-----------------------------------------------------------')
print('Testing the return_doubled_triangle method of the Triangle class')
print('-----------------------------------------------------------')
p1 = Point(30, 75)
p2 = Point(15, 45)
p3 = Point(30, 90)
t1 = Triangle(p1, p2, p3)
t2 = t1.return_doubled_triangle()
print()
print("Testing whether the correct Triangle was returned:")
expected_a = Point(60, 150)
expected_b = Point(30, 90)
expected_c = Point(60, 180)
run_test_instance_variables(t2, expected_a, expected_b, expected_c)
print()
print("Testing that the Triangle itself was not mutated:")
run_test_instance_variables(t1, p1, p2, p3)
def run_test_get_largest_area():
""" Tests the get_largest_area method of the Triangle class. """
print()
print('-----------------------------------------------------------')
print('Testing the get_largest_area method of the Triangle class.')
print('-----------------------------------------------------------')
p1 = Point(5, 5)
p2 = Point(12, 8)
p3 = Point(5, 9)
t1 = Triangle(p1, p2, p3)
area1 = t1.area()
print()
print('Expected for get_largest_area:', area1)
print(' Actual:', t1.get_largest_area())
print_result_of_test(area1, t1.get_largest_area())
t1.shrink_or_expand(6)
area2 = t1.area()
print()
print('Expected for get_largest_area:', area2)
print(' Actual:', t1.get_largest_area())
print_result_of_test(area2, t1.get_largest_area())
t1.shrink_or_expand(0.1)
area3 = t1.area()
print()
print('Expected for get_largest_area:', area2)
print(' Actual:', t1.get_largest_area())
print_result_of_test(area2, t1.get_largest_area())
p1 = Point(5, 5)
p2 = Point(12, 8)
p3 = Point(5, 9)
t2 = Triangle(p1, p2, p3)
area4 = t2.area()
print()
print('Expected for get_largest_area:', area4)
print(' Actual:', t2.get_largest_area())
print_result_of_test(area4, t2.get_largest_area())
print()
print('Expected for get_largest_area:', area2)
print(' Actual:', t1.get_largest_area())
print_result_of_test(area2, t1.get_largest_area())
###############################################################################
# The following are HELPER functions that display error messages in RED
# and help make it easier for us to write tests.
# Do NOT change any of the following.
###############################################################################
def run_test_instance_variables(triangle, expected_a, expected_b, expected_c):
"""
Tests whether the instance variables for the given Triangle
are per the given expected values.
-- Prints relevant messages.
-- Returns True if all is OK, else returns False.
"""
try:
return (run_test_type_of_object(triangle) and
run_test_types_of_instance_variables(triangle) and
run_test_values_of_instance_variables(
triangle,
expected_a,
expected_b,
expected_c))
except Exception:
something_unexpected_happened_in_our_testing_code()
return False
def run_test_values_of_instance_variables(triangle, expected_a, expected_b,
expected_c):
# Print the EXPECTED and ACTUAL values of the instance variables
format_string = ' {:9} {:15} {:15} {:15}'
print(' Testing instance variables:')
print(' a b c')
print(' ------ ------ -------')
print(format_string.format('Expected:', str(expected_a), str(expected_b),
str(expected_c)))
print(format_string.format('Actual:', str(triangle.a), str(triangle.b),
str(triangle.c)))
# Print a message indicating whether or not
# the EXPECTED values are equal to the ACTUAL values.
expected = (expected_a, expected_b, expected_c)
actual = (triangle.a, triangle.b, triangle.c)
return print_result_of_test(expected, actual)
def something_unexpected_happened_in_our_testing_code():
print_failure_message()
explanation = (
' Something unexpected has happened in the testing \n' +
' code that we supplied. You should probably\n' +
' SEEK HELP FROM YOUR INSTRUCTOR NOW.')
print_failure_message(explanation)
def run_test_type_of_object(triangle):
""" Returns True if the argument is in fact a Triangle object """
if isinstance(triangle, Triangle):
return True
else:
explanation = (' The following object to test:\n' +
' ' + str(triangle) + '\n' +
' should be a Triangle object,\n' +
' but it is not. Perhaps your code\n' +
' returned something of the wrong type?')
print_failure_message()
print_failure_message(explanation)
return False
def run_test_types_of_instance_variables(triangle):
"""
Returns True if the argument has the right instance variables
and they are all numbers.
"""
# If NONE of the expected instance variables exist,
# then perhaps the only "problem" is that the __init__ method
# has not yet been implemented.
attributes = dir(triangle)
if ('a' not in attributes
and 'b' not in attributes
and 'c' not in attributes):
explanation = (
' This object:\n' +
' ' + str(triangle) + '\n' +
' should have these instance variables:\n' +
' self.a\n' +
' self.b\n' +
' self.c\n' +
' but it has NONE of them.\n' +
' Perhaps you simply have not yet\n' +
' implemented the __init__ method?\n' +
' (If so, implement it now.)')
print_failure_message()
print_failure_message(explanation)
return False
# If SOME (but not all) of the expected instance variables exist,
# then perhaps something was misspelled in __init__.
if not ('a' in attributes
and 'b' in attributes
and 'c' in attributes):
explanation = (
' This object:\n' +
' ' + str(triangle) + '\n' +
' should have these instance variables:\n' +
' self.a\n' +
' self.b\n' +
' self.c\n' +
' but it is missing some of them.\n' +
' Perhaps you misspelled something\n' +
' in your __init__ code?')
print_failure_message()
print_failure_message(explanation)
return False
# Check that the instance variables are of the right types:
# if not isinstance(cloud.capacity, str):
# explanation = (
# ' This object:\n' +
# ' ' + str(cloud) + '\n' +
# ' has an instance variable capacity with this value:\n' +
# ' capacity: ' + str(cloud.capacity) +
# ' That value should be a STRING, but is isn\'t.\n')
# print_failure_message()
# print_failure_message(explanation)
# return False
#
# if not isinstance(cloud.water, list):
# explanation = (
# ' This object:\n' +
# ' ' + str(cloud) + '\n' +
# ' has an instance variable water with this value:\n' +
# ' water: ' + str(cloud.water) +
# ' That value should be a LIST, but is isn\'t.\n')
# print_failure_message()
# print_failure_message(explanation)
# return False
#
# if not is_list_of_strings(cloud.water):
# explanation = (
# ' This object:\n' +
# ' ' + str(cloud) + '\n' +
# ' has an instance variable water with this value:\n' +
# ' water: ' + str(cloud.water) +
# ' That value should be a list of STRINGS, but is isn\'t.\n')
# print_failure_message()
# print_failure_message(explanation)
# return False
return True
def is_list_of_strings(strings):
return ((strings == [])
or (isinstance(strings[0], str)
and is_list_of_strings(strings[1:])))
def print_result_of_test(expected, actual):
if are_equal(expected, actual):
print(" PASSED the above test -- good!", color="blue")
return True
print_failure_message()
if isinstance(expected, list) or isinstance(expected, tuple):
explanation = (
' For at least one of the above, its Expected value\n' +
' does not equal its Actual value.')
# Note: the printed\n' +
# ' values are the actual values ROUNDED to 1 decimal place.')
print_failure_message(explanation)
return False
def are_equal(a, b):
# We will treat two numbers as being "equal" if they are
# the same when each is rounded to 12 decimal places.
if isinstance(a, Number) and isinstance(b, Number):
return (round(a, 12) == round(b, 12))
# For lists and tuples, their items have to be equal for the
# lists/tuples to be equal.
if isinstance(a, list) and isinstance(b, list):
if len(a) != len(b):
return False
for k in range(len(a)):
if not are_equal(a[k], b[k]):
return False
return True # All the items were equal.
if isinstance(a, tuple) and isinstance(b, tuple):
if len(a) != len(b):
return False
for k in range(len(a)):
if not are_equal(a[k], b[k]):
return False
return True # All the items were equal.
# For all else, they must be equal in the "usual" way:
return a == b
def print_failure_message(message=' *** FAILED the above test. ***',
flush_time=0.5):
""" Prints a message onto stderr, hence in RED. """
time.sleep(flush_time)
print(message, flush=True, color="red")
time.sleep(flush_time)
# To allow color-coding the output to the console:
USE_COLORING = True # Change to False to revert to OLD style coloring
testing_helper.USE_COLORING = USE_COLORING
if USE_COLORING:
# noinspection PyShadowingBuiltins
print = testing_helper.print_colored
else:
# noinspection PyShadowingBuiltins
print = testing_helper.print_uncolored
# -----------------------------------------------------------------------------
# Calls main to start the ball rolling.
# The try .. except prevents error messages on the console from being
# intermingled with ordinary output to the console.
# -----------------------------------------------------------------------------
try:
main()
except Exception:
print('ERROR - While running this test,', color='red')
print('your code raised the following exception:', color='red')
print()
time.sleep(1)
raise