15. Probability of Collision [exercise]

Probability of Collision [exercise]

\  Car 1|
  \     |
    \   |
Car 2 \ |  LEFT  | STRAIGHT | RIGHT
___________________________________
  LEFT  |  0.5   |  0.25    | 0.1
STRAIGHT|  0.25  |  0.02    | 0.1
 RIGHT  |  0.1   |  0.1     | 0.01

The truth table shown above represents the probability of two cars colliding at an intersection if they both attempt a maneuver at the same time. If Car 1 goes straight and car two goes left, for example, there is a probability of collision of 0.25.

Start Quiz:

def probability_of_collision(car_1, car_2):
    """
    Calculate the probablity of a collision based on the car turns
    Args:
        car_1 (string): The turning direction of car_1
        car_2 (string): The turning direction of car_2
        
    Returns:
        float: the probability of a collision
    """
    # car_1 and car_2 will each be strings whose value will either be 
    # "L" for left, "S" for straight, or "R" for right.
    probability = 0.0 # you should change this value based on the directions.
    
    if car_1 == "L":
        # TODO your code here for when car 1 turns left
    elif car_1 == "S":
        # TODO your code here for when car 1 goes straight
    else:
        # TODO your code here for when car 1 turns right
    
    return probability


# This function is used to test the correctness of your code. You shouldn't
# touch any of the code below here (but feel free to look through it to
# understand what "correct" looks like).
def test():
    num_correct = 0
    
    p1 = probability_of_collision("L", "L")
    if p1 == 0.5:
        num_correct += 1
    
    p2 = probability_of_collision("L", "R")
    if p2 == 0.1:
        num_correct += 1
    
    p3 = probability_of_collision("L", "S")
    if p3 == 0.25:
        num_correct += 1
    
    p4 = probability_of_collision("S", "R")
    if p4 == 0.1:
        num_correct += 1
    
    print("You got", num_correct, "out of 4 correct")
    
test()

User's Answer:

(Note: The answer done by the user is not guaranteed to be correct)

def probability_of_collision(car_1, car_2):
    """
    Calculate the probablity of a collision based on the car turns
    Args:
        car_1 (string): The turning direction of car_1
        car_2 (string): The turning direction of car_2
        
    Returns:
        float: the probability of a collision
    """
    # car_1 and car_2 will each be strings whose value will either be 
    # "L" for left, "S" for straight, or "R" for right.
    probability = 0.0 # you should change this value based on the directions.
    
    if car_1 == "L":
        # TODO your code here for when car 1 turns left
        if car_2 == "L":
            probability = 0.5
        elif car_2 == "S":
            probability = 0.25
        else:
            probability = 0.1
    elif car_1 == "S":
        # TODO your code here for when car 1 goes straight
        if car_2 == "L":
            probability = 0.25
        elif car_2 == "S":
            probability = 0.02
        else:
            probability = 0.1
    else:
        # TODO your code here for when car 1 turns right
        if car_2 == "L":
            probability = 0.1
        elif car_2 == "S":
            probability = 0.1
        else:
            probability = 0.01
    
    return probability


# This function is used to test the correctness of your code. You shouldn't
# touch any of the code below here (but feel free to look through it to
# understand what "correct" looks like).
def test():
    num_correct = 0
    
    p1 = probability_of_collision("L", "L")
    if p1 == 0.5:
        num_correct += 1
    
    p2 = probability_of_collision("L", "R")
    if p2 == 0.1:
        num_correct += 1
    
    p3 = probability_of_collision("L", "S")
    if p3 == 0.25:
        num_correct += 1
    
    p4 = probability_of_collision("S", "R")
    if p4 == 0.1:
        num_correct += 1
    
    print("You got", num_correct, "out of 4 correct")
    
test()

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