I have written my bus traffic simulation in Python. Python, because this is my favourite programming language that I am using daily. For implementation I have used Windows OS and Eclipse Juno.

To run the simulation use:

python main.py inputs/simpleInputWithoutOptimise.dat

• where the second term specifies input file that will be used for simulation.

This command will output all simulation to command line (together with statistics, optimised parameters, warnings or errors)

I have written some test for my simulation.

To run these use:

python unitTest.py

It contains all tests I have written. I have added all tests into one file just for simpler test process.

Test contains tests for testing:

• if simple file without experiments is parsed correctly
• if events are calculated correctly separately for boarding and disembarking the bus, arriving and leaving the stop
• if simulation outputs correct events and accurate statistics by using seed
• if file with experiments is parsed correctly and correct states are created
• if file catches errors and warnings (valid/invalid inputs)

Warning shown:

• if route with zero capacity found

Since simulation can still be run, considering routes with empty capacity as a valid input, however, since it is quite strange to have such a "route" showing a warning to user.

Error shown:

• if route with only one stop found

Firstly, I was thinking that this should be a warning, however, after thinking about it more carefully I have decided to consider routes with only one stop as invalid since in case no other routes operates through this stop, if new passenger comes to this stop, he will not be able to go everywhere (destination stop cannot be the same as origin stop and no other options are available, because no other routes operates through this stop)

• if route with same number found more than once
• if more than one road with identical starting and ending stops found

I was thinking about showing warning if two identical routes/roads have been found. However, I have decided to consider this as an error since the original simulation would have two identical routes/roads that might be mixed up by the simulation (unless, of course, we are removing these identical instances from our state)

From the beginning I have tried to write my code as efficient as possible. When I was designing my simulator I decided to do as much work as possible when updating the state rather than while calculating possible events, because there are a lot of events that won't be picked up (actually only one will be) and that would be not efficient (hence only most important information that would allow to know what kind of event is possible and the rate of that event is calculated while everything else is done while updating the state after picking one event)

At the end of implementation I have additionally used profiler with the following command:

python -m cProfile main.py *

where * means different test inputs

I have found out that splitting bus id to get route number was very inefficient (even though it was using this operation very often). Therefore, I have changed my code so now Bus object also keeps route number (not only bus id) and when looking for route number there is no need to split bus id to get it. With this change I have managed to make my simulator 2 tiems faster.

I have also found that remove function (for list objects, not deque) is less efficient than list comprehension, hence I am using list comprehension and it made my simulator even more faster.