Random 15 Championship 2018/19: Round 4

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tractakid
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Re: Random 15 Championship 2018/19: Round 4

Post by tractakid » 17 Mar 2019, 21:30

Twas a fun challenge yesterday. I made a few route errors but still managed to come joint-first!

Notably, forgetting the Paddington to Lancaster Gate run, forgetting to check the branch of my Northern Line train and going the wrong way north from Kennington (Only realising at Borough!) and forgetting that the Hammersmith & City Line goes from Kings Cross, going on the Northern Line and changing at Moorgate instead :lol:

The more you do R15s, the better you get at them, but also the more opportunities there are to feel stupid as you make mistakes!
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Going Underground
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Re: Random 15 Championship 2018/19: Round 4

Post by Going Underground » 18 Mar 2019, 12:45

How NOT to do an R15 - sorry Das.... :oops:

When setting off at the start don't assume the departure board is correct showing 3 mins for your next train and amble down the stairs to see train doors closing on you and all the other teams going that direction safely onboard

Why change at Paddington H & C to run to District/Circle when a change at Edgware Road would surely have been easier :roll:

Why stay on the number 4 bus for 2 extra stops when the lights are red and you can see the stop you want and then decide not to get of there anyway but go around the corner to stop even further away :roll:

Don't jump on the first bust you see on a long straight road assuming that route will be staying on that road and going where you want - just ask the driver :!: :!:

How many of these have I done now..... :(
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dstock17
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Re: Random 15 Championship 2018/19: Round 4

Post by dstock17 » 18 Mar 2019, 18:36

LOL even the best have bad days Kevin
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michael_churchill
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Re: Random 15 Championship 2018/19: Round 4

Post by michael_churchill » 19 Mar 2019, 16:52

I'll just add what my program thinks is the optimum solution, allowing 2 minutes for getting to a new platform and waiting for the next train each time you need to change lines...

Start at Great Portland Street
Circle / Hammersmith & City / Metropolitan to Baker Street, towards Hammersmith (Circle / H&C) / Amersham / Uxbridge / Watford / Chesham [2min]
Bakerloo to Paddington (Bakerloo / Circle / District), towards Harrow & Wealdstone [3min 30sec + 2min for changing]
-
Circle / District to Notting Hill Gate, towards Hammersmith (Circle / H&C) / Ealing Broadway / Richmond / Wimbledon / Kensington (Olympia) [3min 30sec + 2min for changing]
Central to Marble Arch, towards Epping / Woodford [5min 30sec + 2min for changing]
-
Central to Oxford Circus, towards Epping / Woodford [2min 45sec]
Victoria to Warren Street, towards Walthamstow Central [1min 40sec + 2min for changing]
Northern to Mornington Crescent, towards Edgware / High Barnet / Mill Hill East [3min 30sec + 2min for changing]
-
Northern to Kentish Town, towards High Barnet / Mill Hill East [3min 45sec]
-
Northern to King's Cross St Pancras, towards Morden, via Bank [7min + 2min for changing]
Piccadilly to Caledonian Road, towards Cockfosters [3min + 2min for changing]
-
Piccadilly to Holloway Road, towards Cockfosters [1min 30sec]
-
Piccadilly to King's Cross St Pancras, towards Uxbridge / Heathrow Terminal 5 / Hatton Cross [5min + 2min for changing]
Circle / Hammersmith & City / Metropolitan to Moorgate, towards Edgware Road (Circle / District / H&C) / Barking / Aldgate [6min 30sec + 2min for changing]
-
Hammersmith & City to Stepney Green, towards Barking [9min]
-
District / Hammersmith & City to Bromley-by-Bow, towards Upminster / Barking [5min 30sec]
-
District to Temple, towards Ealing Broadway / Richmond / Wimbledon / Kensington (Olympia) [20min 30sec + 2min for changing]
-
Circle / District to Embankment, towards Edgware Road (Circle / District / H&C) / Ealing Broadway / Richmond / Wimbledon / Kensington (Olympia) [1min 30sec]
Northern to Stockwell, towards Morden [8min 30sec + 2min for changing]
Victoria to Brixton [1min 50sec + 2min for changing]
-
Victoria to Green Park, towards Walthamstow Central [9min 20sec + 2min for changing]
Piccadilly to Hyde Park Corner, towards Uxbridge / Heathrow Terminal 5 / Hatton Cross [2min + 2min for changing]
-
Piccadilly to Earl's Court, towards Uxbridge / Heathrow Terminal 5 / Hatton Cross [7min 30sec]
District to West Kensington, towards Ealing Broadway / Richmond [2min + 2min for changing]
-
District to Earl's Court, towards Upminster / Edgware Road (Circle / District / H&C) [2min 30sec + 2min for changing]
District to Putney Bridge, towards Wimbledon [7min + 2min for changing]
-
Total = 2hr 40min 20sec

Thoughts?

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greatkingrat
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Re: Random 15 Championship 2018/19: Round 4

Post by greatkingrat » 19 Mar 2019, 17:21

Why is it making an extra change onto the Bakerloo at the beginning instead of just going straight to Edgware Road (Circle)?
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RJSRdg
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Re: Random 15 Championship 2018/19: Round 4

Post by RJSRdg » 19 Mar 2019, 23:08

Especially considering that neither changing from the westbound H&C to the Bakerloo at Baker Street, or the Bakerloo to the District at Paddington are particularly easy changes.
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alexmcmotor
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Re: Random 15 Championship 2018/19: Round 4

Post by alexmcmotor » 20 Mar 2019, 10:54

I would say the blanket '2 minutes for changing' is a pretty poor approximation. It isn't too bad if you consider that it may average out over a challenge, but I think it becomes an issue at places like changing from Northern to H&C at Kings Cross; it takes a minute to do the change at speed and then you could be waiting anything up to 10 minutes for a train, in cases of low service frequency I think such a simple approximation really falls apart. If a specification of your program is that it doesn't read from the WTTs to get train times, which would be part of an optimal solution, then to improve it I would store average changing times from each line to each line at an interchange, accounting for both station geography and service frequency. eg Victoria-Bakerloo at Oxford Circus would be 1min (negligible change time + avg. 1 min waiting time) where as Northern-H&C would be more in the order of 6 minutes. I wouldn't want to have to write the scripts and memory for that functionality though :lol:

I would be interested to see the algorithms that your program uses to come up with its solution though :) , as I recently spent several weeks implementing Dijkstra's algorithm over a graph in C for my degree.
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Re: Random 15 Championship 2018/19: Round 4

Post by michael_churchill » 20 Mar 2019, 11:46

greatkingrat wrote:
19 Mar 2019, 17:21
Why is it making an extra change onto the Bakerloo at the beginning instead of just going straight to Edgware Road (Circle)?
I thought this would come up...

It makes the extra change because it calculates the route between each pair of stations separately and in isolation. This is known as the "travelling salesman problem". Imagine a salesman has a set of clients to visit in one day. In what order should he visit the clients to have the minimum amount of travelling? Because he's stopping to visit the client, it's the total travelling time or distance that he's interested in. In tube running terms, it's like us having to leave the station each time before you can catch the next train. For a Random 15, I've added a "Continuous journey?" tick box so that it will add a "changing time" when ending one "leg" and starting the next requires changing lines. So, it should find the quickest way to "join the dots" when there are fewer changes at the "dots".

In this case, because it is heading towards Marble Arch, "Great Portland Street to Paddington via Edgware Road" is best. If a station further up the Bakerloo line like Maida Vale was also on the list, it would have to consider visiting that after Paddington and then "Great Portland Street to Paddington via Baker Street" would be better. To summarise, "It's not easy!"

In isolation, according to the times I got from the working timetables, that is the quickest way from Great Portland Street to Paddington (B/C/D).
Start at Great Portland Street
Circle / Hammersmith & City / Metropolitan to Baker Street, towards Hammersmith (Circle / H&C) / Amersham / Uxbridge / Watford / Chesham [2min]
Bakerloo to Paddington (Bakerloo / Circle / District), towards Harrow & Wealdstone [3min 30sec + 2min for changing]
= 7min 30sec
Start at Great Portland Street
Circle / Hammersmith & City / Metropolitan to Edgware Road, towards Hammersmith (Circle / H&C) / Amersham / Uxbridge / Watford / Chesham [4min 30sec]
Circle / District to Paddington (Bakerloo / Circle / District), towards Notting Hill Gate [2min + 2min for changing]
= 8min 30sec
RJSRdg wrote:
19 Mar 2019, 23:08
Especially considering that neither changing from the westbound H&C to the Bakerloo at Baker Street, or the Bakerloo to the District at Paddington are particularly easy changes.
The program has no idea what an "easy change" is. At the moment you can enter a overall "time for changing" which should include time for changing platforms and the time you should expect to wait for the next train. As alexmcmotor points out, to represent "easy changes", I would probably have to include walking distances between each combination of pairs of platforms at stations. For expected waiting times, I would have to at least do it by line, to allow for the different frequencies of, for example, the Victoria line and the Overground.
alexmcmotor wrote:
20 Mar 2019, 10:54
I would be interested to see the algorithms that your program uses to come up with its solution though :) , as I recently spent several weeks implementing Dijkstra's algorithm over a graph in C for my degree.
Warning: maths-geekery incoming!
For calculating the route from A to B, it does use Dijkstra's algorithm. For multi-stop routes like Random 15, it effectively uses Dijkstra but where "A having visited B but not C and D" and "A having visited C but not B and D" are separate nodes. To simplify things, only stations that are interchanges are nodes in the network. For example, Baker Street and Euston Square (because you can walk to Euston) are nodes and "H&C/Circle/Met" is an edge between them. If you want to calculate a route from (or to) Great Portland Street, it temporarily adds that as a node on that edge.

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Re: Random 15 Championship 2018/19: Round 4

Post by RJSRdg » 22 Mar 2019, 23:10

Going Underground wrote:
18 Mar 2019, 12:45


Don't jump on the first bust you see
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tangy
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Re: Random 15 Championship 2018/19: Round 4

Post by tangy » 02 Apr 2019, 19:25

The results of round 4 of the 2018/19 Random 15 Championship that was held on Saturday 16th March 2019.

This was a normal round but with a live draw with challengers picking raffle tickets out of a bucket just before the start at Great Portland Street. Each station had its own number allocated, however in compiling this station list I mistakenly overlooked one of the stations... that being Kensington Olympia and this wasn't realised until at the meet up (despite me double checking the station list at least twice)!

As I didn't bring my raffle ticket book to add an extra number, it was decided that Olympia would be excluded from the draw.

However, all the other stations were represented and this is what was drawn:
--Great Portland Street (meet up)
--Marble Arch
--Putney Bridge
--Hyde Park Corner
--Holloway Road
--Mornington Crescent
--Stepney Green
--West Kensington
--Caledonian Road
--Brixton (LU)
--Paddington (Praed Street)
--Kentish Town
--Temple
--Bromley-by-Bow
--Moorgate

There were 13 challengers who split up into 10 teams (therefore all teams scored points).

10th: Kevin Brown and Das Stevens- 03:36:41 at Bromley-by-Bow
=8th: Andrew Baker and David Jay- 03:31:06 at Bromley-by-Bow
=8th: Michael Churchill- 03:31:06 at Bromley-by-Bow
7th: David Edwards- 03:16:27 at Brixton (LU)
6th: Clive Burgess- 03:10:25 at Bromley-by-Bow
5th: Peter Smyth- 03:02:42 at Brixton (LU)
4th: Tangy- 02:55:57 at Bromley-by-Bow
=1st: Alex Kneller and Kat Hopper- 02:24:03 at Bromley-by-Bow
=1st: Andrew Chilcraft- 02:48:03 at Bromley-by-Bow
=1st: Hugo Marrow- 02:48:03 at Bromley-by-Bow

Adding these scores into the leaderboard:

1. David Edwards: 38 points overall [4 rounds attended]
2. Clive Burgess: 35 [4]
3. Hugo Marrow: 30 [3]
4. Tangy: 28 [4]
5=. Andrew Baker: 26 [4]
5=. Andrew Chilcraft: 26 [3]
7. Kevin Brown: 22 [4]
8. Peter Smyth: 18 [4]
9. Alex Kneller: 15 [4]
10. Kat Hopper: 14 [2]
11. Michael Churchill: 9 [4]
12. Mike Townley: 8 [1]
13=. Damian Cook: 6 [1]
13=. Matthew Cook: 6 [1]
13=. Samuel Mills: 6 [1]
16. Rhys Benjamin: 5 [1]
17=. Nick Gardner: 4 [2]
17=. Simon Kneller: 4 [3]
19=. Rob Lomas: 3 [3]
19=. David Jay: 3 [1]
21=. Richard Standing: 1 [3]
21=. Das Stevens: 1 [4]
23=. Felix Andrew: 0 [2]
23=. Max Shepherd: 0 [2]
23=. Andi James: 0 [1]
23=. Rhys Jackson: 0 [1]
23=. Lee Maxter: 0 [1]

See you all again for the next round(the marathon twist) on Saturday 27th April 2019.

Tangy
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al
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Re: Random 15 Championship 2018/19: Round 4

Post by al » 03 Apr 2019, 08:40

I'm guessing there's a typo in Alex and Kat's final time?
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Re: Random 15 Championship 2018/19: Round 4

Post by alexmcmotor » 05 Apr 2019, 23:03

al wrote:
03 Apr 2019, 08:40
I'm guessing there's a typo in Alex and Kat's final time?
That's correct! As the positions would suggest, we did actually match Hugo and Andrew C's time.
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