FM-Contest: Tactics

As I announced in my last articles I’ve submitted a programmed bot for the contest organized by freiesMagazin. Here I present my bots tactics.

The submitted bots are grouped to teams. On one hand the BLUE team, or preys, they have to run and hide. On the other hand the RED team, or predators, their task is to catch a bot of the BLUE team. If anyone of the BLUE team got captured by a RED team member he changes the team from BLUE to RED. If there was no teamchange for a longer time, one of the BLUE team is forced to change. That are the simplified tasks, for more details visit their website. All in all if you are BLUE run and hide, otherwise hunt the BLUE’s.

The map is very simple organized, there are wall-fields and floor-fields. You are neither able to access wall-fields nor to see through such fields. Floor-fields are acessible, but toxic. So they decrease your health status. You can look in each of eight directions: NORTH, NORTH_WEST, WEST, SOUTH_WEST, SOUTH, SOUTH_EAST, EAST, NORTH_EAST. You’ll only see enemies that are standing in the direction you are looking to (180°) and don’t hide behind a wall. Positions of your team members are told by communicators, so you’ll know where your team is hanging around. In each round you’re able to walk exactly one field in one of eight directions, and you can choose where to look for the next turn.

That are the basics. How does my bot handle each situation? In general with every turn my bot tries to look in the opposite direction. To see at least every second round all see-able enemies (those that are not behind a wall).

Suppose to be a BLUE team member, my bot first checks whether it has seen a RED one within the last rounds. If there was an enemy the bot of course has to run! That is, my bot holds a so called distance map for every opponent. This map tells my bot how many turns each opponent needs to reach a single point on the map. These distance maps are created via an adaption of Dijkstra’s algorithm [Dij59]. So in principle the bot could search for a position on the map, that it reaches before any of the enemies can reach it. But there is a problem. Consider a room you’re hiding in, that has two doors, and an enemy is entering this room through one of these doors. Finding the best field concerning these distance maps means in too many times running in the opposite direction of the enemies door. Hence, you’ll reach a blind alley and drop a brick. So it might be more promising to first check the doors whether you are faster as your enemy or not and decide afterward where to go. Unfortunately there are no doors defined on the map, but I’ll explain in a next article how to parse the map.

If my bot is BLUE and no RED bot is in sight he calls one random room out of a multinomial distribution of rooms. Here each rooms gets a score resulting from its position. The score is bigger the shorter the distance to the room and the higher the distance from this room to the center of the map (try to remain on the sidelines). These scores are normalized, you can understand them as a multinomial distribution. So the bot is searching for a room that is near and in a corner of the map. Of course random, cause enemies might search for it in optimal rooms ;-) If that room is reached the bot will hang around there (as far away as possible from doors and at positions with minimal toxicity) until a teammate has change the team (this bot still knows where we are) or at least every 20 rounds to raise the entropy in the motion profile. While these room changes the bot is very vulnerable to loitering enemies, but nevertheless it might be a weaker victim if it stays in one and the same room all the time…

On the other side of life, when the bot is RED, there is no time for chilling out in a room far away from all happenings. It should be inside, not only near by. If it’s seeing a BLUE bot he’s of course following and tries to catch it. Here would be space to predict flee-possibilities of our victims to cut their way. But due to a lack of time this bot is simply following it’s victims. Nobody visible? Go hunting! The bot tries to find the prey that was last seen on it’s position where we’ve seen it. That’s the next place for advantages. I’m tracking motion profiles of any opponent, here one could use these information to predict a better position for the opponents (for example using neural networks or something like this)… If no enemy can be found my bot is canvassing all rooms of the map, trying to find anyone to catch. Within this exploration of the map it is always interested in going long ways through the map. The more rooms it’s visiting the higher the probability to find someone..

Each turn is limited to a maximum of five seconds to decide what to do. In my first attempt I tried to process these tactics by threading. The idea was to hold the main tool in a loop, testing whether 5 secs are over or the AI has finished searching for a next turn. So the AI could decide for different proceedings within this time, based on scores, and this algorithm would be something like anytime. That means anytime you’ll stop it there is a decision for a next step, the later you stop it the better the decision. Due to the simplicity of my AI I decided against this procedure. So the possible actions are processed without threads. But if you take a look at the code, you’ll find a lot of rudiments remaining, didn’t had the leisure to clean up…


Edsger W. Dijkstra A note on two problems in connexion with graphs Numerische Mathematik, 1(1):269–271–271, December 1959.

Created an AI for a contest

This year the journal freiesMagazin organized the third contest in a series. This time it’s about programming an AI for a predator-prey-like game. I just submitted my short solution.

As I said, it’s the third programming contest. The first one was about switching gems and in the second contest it was the goal to navigate a robot through a factory. I didn’t got the announce of the first one and missed the second one as a consequence of a lack of time. Hence it’s a premiere for me!

Citing their introduction:

Same procedure as every day: It is late in the evening and you're still sitting at your office desk and listening to some music. Suddenly a siren sounds through all rooms, the doors are closing automatically and you cannot open them anymore. A light green mist appears and some creepy shapes wander around the hall. Sometimes you really hate Mondays …

So, at the beginning of the game all programmed bots are in the same team. After some time one of them changes to the opposite team, trying to catch one of the other while the other ones are fleeing. Simple and clear. It’s running through sockets and the bot-programmers can win vouchers. More information can be found at their website.

On one hand I’m interested in socket programming since a while and on the other hand I’m of course interested in the voucher, so I decided to take part in the contest although there are enough other things to do for me. I agreed with myself to put about two days of work into it. In the end I worked about three days, but however, I could program about 365 more. If you take a look at the code it’s kept more or less simple and many functions aren’t in use. For example I track a motion profile of each opponent, but when I’m predator I don’t care about it. It would be more promising to predict a actual position of a prey (for example with neural networks or something like that) instead of searching without any profoundness. But this would go beyond my scope…

So lets see how many people are also joining this contest. The result will be published mid-January. At least I’m last, but that’s not wicked. I had a lot of fun and even learned something. That’s the main thing. It’s taking part that counts! ;-)

I attached my bot, it’s licensed under GPLv3. In some further articles I’ll explain some smart details of my code, I think some of them are quiet nice to know.

Download: Java: Repository @ GitHub (Please take a look at the man-page. Browse bugs and feature requests.)

Vim plugin for R

Just found a very nice plugin for using R in Vim. It’s unbelievable comfortable!

There are at least two ways to install it. If your are working on a Debian based distro you can use the .deb package provided by the author Jakson Alves de Aquino itself. On this site you’ll also find some smart screen shots. Another way is the installation by hand (I did so). Download the package, in your download directory type something like this:

mkdir -p ~/.vim 
unzip vim-r-plugin-*.zip -d ~/.vim

Yes, that’s it! To start an R session just open a R-file ( .R or .Rnw or .Rd ) with vim and type \\rf . To close the session type \\rq (not saving hist) or \rw (saving history). The handling needs to getting used to.. Here is a list of common commands from the documentation (might want to print them as a cheat sheet!?) :

  . Start R (default)                                    \\rf
  . Start R --vanilla                                    \\rv
  . Start R (custom)                                     \\rc
  . Close R (no save)                                    \\rq
  . Close R (save workspace)                             \\rw

  . File                                               \\aa
  . File (echo)                                        \\ae
  . File (open .Rout)                                  \\ao
  . Block (cur)                                        \\bb
  . Block (cur, echo)                                  \\be
  . Block (cur, down)                                  \\bd
  . Block (cur, echo and down)                         \\ba
  . Function (cur)                                     \\ff
  . Function (cur, echo)                               \\fe
  . Function (cur and down)                            \\fd
  . Function (cur, echo and down)                      \\fa
  . Selection                                          \\ss
  . Selection (echo)                                   \\se
  . Selection (and down)                               \\sd
  . Selection (echo and down)                          \\sa
  . Paragraph                                          \\pp
  . Paragraph (echo)                                   \\pe
  . Paragraph (and down)                               \\pd
  . Paragraph (echo and down)                          \\pa
  . Line                                                \\l
  . Line (and down)                                     \\d
  . Line (and new one)                                  \\q

  . List space                                         \\rl
  . Clear console                                      \\rr
  . Clear all                                          \\rm
  . Object (print)                                     \\rp
  . Object (names)                                     \\rn
  . Object (str)                                       \\rt
  . Arguments (cur)                                    \\ra
  . Example (cur)                                      \\re
  . Help (cur)                                         \\rh
  . Summary (cur)                                      \\rs
  . Plot (cur)                                         \\rg
  . Plot and summary (cur)                             \\rb
  . Update Object Browser                              \\ro
  . Set working directory (cur file path)              \\rd
  . Build R tags file                   :RBuildTags
  . Build omniList (loaded packages)    :RUpdateObjList
  . Build omniList (installed packages) :RUpdateObjListAll
  . Sweave (cur file)                                  \\sw
  . Sweave and PDF (cur file)                          \\sp
  . Go to next R chunk                                  gn
  . Go to previous R chunk                              gN

But if you got used to, it’s very handy! At the start-up it opens a new R-console (just close it, doesn’t matter) and you can send single lines, a block or a whole file to R (see the documentation). Every thing I tried worked really fine!

A small example in action is presented in the image. In an earlier post I explained how to produce such a title consisting of R objects and Greek letters.

I’ve attached the documentation of this plugin, first and foremost for me for cheating, but of course you’re allowed to use it also ;-)

Download: HTML: Vim-R-plugin documentation (Please take a look at the man-page. Browse bugs and feature requests.)

Open Research Computation

I want to announce a new scientific journal: Open Research Computation.

I think it sounds quiet interesting, citing their aims & scope:

Open Research Computation publishes peer reviewed articles that describe the development, capacities, and uses of software designed for use by researchers in any field. Submissions relating to software for use in any area of research are welcome as are articles dealing with algorithms, useful code snippets, as well as large applications or web services, and libraries. Open Research Computation differs from other journals with a software focus in its requirement for the software source code to be made available under an Open Source Initiative compliant license, and in its assessment of the quality of documentation and testing of the software. In addition to articles describing software Open Research Computation also welcomes submissions that review or describe developments relating to software based tools for research. These include, but are not limited to, reviews or proposals for standards, discussion of best practice in research software development, educational and support resources and tools for researchers that develop or use software based tools.

Looking forward…

You may also be interested in a more detailed announce: Can a journal make a difference? Let’s find out.

Martin Scharm

stuff. just for the records.

Do you like this page?
You can actively support me!