Question

This program will provide the user the tools to make up trains from a file of available cars. The car data will be the reporting identifier, car type, weight (in tons) and length (in feet) for each car. The user can select to make up a train by total weight, total length or car type. The user will be able to display any train’s consist, and will be able to delete a train (returning the cars to the pool of available cars.)

General algorithm

Read the data file, storing to list of lists ( one car per sublist )

If file did not open or is empty, display message and exit

As long as quit option not selected:

Display menu, get choice

Make train by weight – pick first available cars that do not cause total weight to exceed desired weight. Some cars may be skipped. Total weight may be less than desired weight if not enough available cars.

Make train by length – pick first available cars that do not cause total length to exceed desired length. Some cars may be skipped. Total length may be less than the desired length if not enough available cars.

Make train by car type – pick first available cars of a specified type, up the maximum number of cars specified. Number of cars may be less than the desired number if not enough available cars.

Display train – present the range of train numbers (1 to highest assigned), display each cars’ data. If train is empty, display message.

Delete train – present range of train numbers (1 to highest assigned ). Delete cars in train’s list and reset all cars in pool to indicate available.

Quit – display message, end program.

Making up a train

Start by making an empty list for the current train.

You will make a train by looking through the car lists, one at a time, checking the type, weight or length field to determine if it can be added the train being built and if the car is available.

If building by weight or length, you’ll add a car’s weight or length to a total as you go along. Test each car that its value, when added to the total, does not exceed the desired total. If it can be added without exceeding the desired total, set the last field (the 0) to the train number, then append that car to the train. (It will remain in the master list, but now is marked as in a train.)

If building by car type, you won’t be concerned about weight or length. Keep adding available cars of the desired type until the maximum number of cars is reached, or there are no more cars.

In either type of train building, continue examining all cars until either the maximum value (weight, length, number of cars) has been reached, or there are no more cars to check.

When the new train is complete, return it to main( ).

Functions:

Your program must have the following functions:

main( ) starts the program. Opens and checks the data file, calls the read_file, loops as long as quit option not chosen, executing the selected option.

read_file( ) given open file handle, reads data into list of lists. Returns list, empty list if no data

choose_option( ) displays menu of options, gets and validates option. Return choice as an integer

choose_car_type( ) displays list of car types, get user selection. Validate selection, return car type as string

make_train_wt( ) given list of cars, limit and train number, selects cars to make selected train type. Marks cars with train number in main car list. Return train as a list

make_train_len( ) given list of cars, limit and train number, selects cars to make selected train type. Marks cars with train number in main car list. Return train as a list

make_train_type( ) given list of cars, limit, car type and train number, selects cars to make selected train type. Marks cars with train number in main car list. Return train as a list

display_train( ) given a list that holds one train, display the cars’ information in formatted form

delete_train( ) given list of cars and train number, marks all of trains cars as available (0)

I'm writing this in Python Geany.

Answer 1

Code:

Code as text:

''' read data from a file into list of lits and return it '''

def read_file(f):

car_list = []

for line in f.readlines():

car = [x for x in line.strip().split(' ')]

car.append(0)

car_list.append(car)

return car_list

''' display menu of options, return choice as integer. '''

def choose_option():

print("1. Make train by weight")

print("2. Make train by length")

print("3. Make train by car type")

print("4. Display train")

print("5. Delete train")

print("0. Quit")

option = int(input("Enter option: "))

while option < 0 or option > 5:

print("Invalid option! Try again.")

option = int(input("Enter option: "))

return option

'''' displays list of car types, get user selection and return it '''

def choose_car_type():

car_types = ['boxcar', 'flatcar', 'goods', 'wagon']

print("Available car types are: ")

for car in car_types:

print(car, end=' ')

print("")

choice = input("Choose car type: ")

while choice not in car_types:

print("Invalid choice! Try again.")

choice = input("Choose car type: ")

return choice

''' makes a train by weight '''

def make_train_wt(cars_list, limit, train_num):

total_wt = 0.0

train = []

for car in cars_list:

car_wt = float(car[1])

if (car[3] == 0) and (total_wt + car_wt < limit):

total_wt += car_wt

car[3] = train_num

train.append(car)

return train

''' makes train by length '''

def make_train_len(cars_list, limit, train_num):

total_len = 0

train = []

for car in cars_list:

car_len = float(car[2])

if (car[3] == 0) and (total_len + car_len < limit):

total_len += car_len

car[3] = train_num

train.append(car)

return train

''' makes train by car type '''

def make_train_type(cars_list, limit, cartype, train_num):

total_cars = 0

train = []

for car in cars_list:

car_type = car[0]

if (car[3] == 0) and (car_type == cartype):

total_cars += 1

car[3] = train_num

train.append(car)

if total_cars == limit:

break

return train

''' display the cars in a train '''

def display_train(train):

if len(train) == 0:

print("The train is empty!")

return

print("The train is: ")

i = 0

for car in train:

i += 1

print("Car #", i)

print("Type: %s\t Weight: %stons\t Length: %sfeets" % (car[0], car[1], car[2]))

''' mark cars as available '''

def delete_train(cars_list, train_num):

for car in cars_list:

if car[3] == train_num:

car[3] = 0

''' main driver function '''

def main():

try:

carsfile = open('cars.txt', 'r')

cars_list = read_file(carsfile)

carsfile.close()

except IOError:

print("Error! File not found.")

return

trains = []

train_num = 0

while True:

option = choose_option()

if option == 1:

weight = float(input("Enter desired weight: "))

train_num += 1

trains.append(make_train_wt(cars_list, weight, train_num))

print('Train Created! Train number is', train_num)

if option == 2:

length = float(input("Enter desired length: "))

train_num += 1

trains.append(make_train_len(cars_list, length, train_num))

print('Train Created! Train number is', train_num)

if option == 3:

cartype = choose_car_type()

limit = int(input("Enter number of cars: "))

train_num += 1

trains.append(make_train_type(cars_list, limit, cartype, train_num))

print('Train Created! Train number is', train_num)

if option == 4:

num = int(input("Enter train number: "))

display_train(trains[num - 1])

if option == 5:

num = int(input("Enter train number: "))

delete_train(cars_list, num)

if option == 0:

print("Exiting...")

return

# call to main function

if __name__ == "__main__":

main()

Sample run:

Input file: cars.txt

Output: