ikristina / TrainStationsTask

The Problem:

The local commuter railroad services a number of towns in Kiwiland. Because of monetary concerns, all of the tracks are 'one-way.' That is, a route from Kaitaia to Invercargill does not imply the existence of a route from Invercargill to Kaitaia. In fact, even if both of these routes do happen to exist, they are distinct and are not necessarily the same distance!

Full description of the problem and needed implementation can be found in task.txt file.

How To Use

The code was implemented using Python 3.6. No additional libraries required to install.

Use unittests.py file for unit tests or main.py to add data on-the-go.

definitions contains classes of towns as Nodes, routes between towns as Edges and all the route map as Graphs. Graph is weighted directed, represented by dict in python: {Node: [Edge1, Edge2]...} main.py is a console program to operate the Train System. unittests.py contains 10 unittests from the task in task.txt

All the unit tests have passed:

..........
----------------------------------------------------------------------
Ran 10 tests in 0.001s

OK

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Using main.py

Run the following in terminal (assuming Python 3 is the default Python version):

python main.py

The first output of the program is:

Start by adding towns and distances: add_route
To see available commands type 'help' or '?'
To exit press command+D (Mac) or ctrl+D (Linux)

Following the instructions has to be straightforward.

add_route command is used to add Nodes - Towns and Edges - Routes along with Weights - Distances.

(Cmd) add_route
Do you want to use default graph or enter your own?
Type 'default' or 'my'

You can use default graph which can be represented as following:

To see what's in a graph type `show_graph'

(Cmd) show_graph
Representation of the graph:
{A: [AB5, AD5, AE7], B: [BC4], C: [CD8, CE2], D: [DC8, DE6], E: [EB3]}

In the example above keys A, B, C, D, E are representations of Nodes, values [AB5, AD5, AE7] etc. are representations of Edges with weights.

If you want to create your own graph then type my and not default, then follow the instructions:

(Cmd) add_route
Do you want to use default graph or enter your own?
Type 'default' or 'my'
> my
Enter first town name: 
> King
First town King has been saved
Enter second town name: 
> Queen
Second town Queen has been saved
Enter distance between two cities: 
> 2
Thank you, the route KingQueen2 has been saved.

Then you will be asked:

 Would you like to add more? (y/n)

If you chose n you will not be able to add it later.

Now the graph looks like this:

(Cmd) show_graph
Representation of the graph:
{King: [KingQueen2]}

To compute the distance between given Towns use calculate_distance command. You must use the format A-B-C. You may use it as a parameter to calculate_distance or pass it later when asked.

(Cmd) calculate_distance A-B-C
9

(Cmd) calculate_distance
Type desired route in format: A-B-C
> A-D
5

To count the number of trips between two points with a given maximum number of stops use count_trips_max_stops <start point> <finish point> <max number of stops>.

To count the number of trips between two points with a given exact number of stops use count_trips_exact_stops <start point> <finish point> <exact number of stops>

(Cmd) count_trips_exact_stops A C 4
Number of trips from A to C given 4 exact number of stops is 3

To find a shortest route in term of distance use shortest_route <start> <finish> command.

(Cmd) shortest_route A C
The shortest distance from A to C is 9

To find the number of different routes between two towns with a given maximum distance use count_routes_with_distance <start> <finish> <maximum distance>

(Cmd) count_routes_with_distance C C 30
Number of trips from C to C given maximum distance of 30 is 7