scorer

Dependencies

• mnesia

For correct run, check the mnesia application is running in the background.

Installation

Create your own project with rebar3. sh $ rebar3 new app yourapp

Then in your project path find rebar.config file and add enn as dependency under the deps key: erlang {deps, [ {enn, {git, "https://github.com/BorjaEst/scorer.git", {tag, "<version>"}}} ]}.

Then using compile command, rebar3 will fetch the defined dependencies and compile them as well for your application. sh $ rebar3 compile

At the end for making a release you first need to create your release structure and then making a release with following commands. sh $ rebar3 new release yourrel $ rebar3 release

You can find more information about dependencies in rebar3 - dependencies.

Usage

Load the app using your prefered method. For example in the project folder executing rebar3 shell: sh $ rebar3 shell ===> Booted mnesia 1>

The application is divided into 2 elements: - groups: Gen events where the pools can subscribe to receive the score notifications. - pools: Are a list of {scores, id}, they are subscribed to 1 or more groups from where receive the score updates.

All user functions are defined inside the module src/scorer, however here is an example:

Example

Suppose have 2 groups (ga, gb), 3 pools (pa, pb, p_ab) and the following relations (target):

• Points to g_a, will be reflected in p_a and p_ab
• Points to g_b, will be reflected in p_b and p_ab

To create the groups run: erl 1> {ok, G_a } = scorer:new_group(). {ok,{<0.148.0>,group}} 2> {ok, G_b } = scorer:new_group(). {ok,{<0.150.0>,group}}

After the groups are created, you can create the pools indicating the groups they belong to: erl 3> {ok, P_a } = scorer:new_pool(p_a, [G_a]). {ok,{<0.154.0>,p_a,pool}} 4> {ok, P_b } = scorer:new_pool(p_b, [G_b]). {ok,{<0.158.0>,p_b,pool}} 5> {ok, P_ab} = scorer:new_pool(p_ab, [G_a, G_b]). {ok,{<0.160.0>,p_ab,pool}}

Then if an id let's call john, scores in the group g_a the score will be reflected in the pools p_a and p_ab but not in p_b:

erl 6> scorer:add_score(G_a, john, 100.0). ok 7> scorer:get_score(P_a, john). 100.0 8> scorer:get_score(P_ab, john). 100.0 9> catch scorer:get_score(P_b, john). {'EXIT',{{badarg,john}, [{score_pool,get_score,2, [{file,"/home/borja/Projects/scorer/src/score_pool.erl"}, {line,74}]}, {erl_eval,do_apply,6,[{file,"erl_eval.erl"},{line,684}]}, {erl_eval,expr,5,[{file,"erl_eval.erl"},{line,437}]}, {shell,exprs,7,[{file,"shell.erl"},{line,686}]}, {shell,eval_exprs,7,[{file,"shell.erl"},{line,642}]}, {shell,eval_loop,3,[{file,"shell.erl"},{line,627}]}]}}

Now imagine that a lot of users are scoring in g_a and g_b. You can get the top, bottom or a list using the functions top/2, bottom/2 and to_list/1:

Let's add some random scores to some numeric users: erl 10> [scorer:add_score(G_a, 10 + rand:uniform(9), 1.0) || _ <- lists:seq(1, 9)]. [ok,ok,ok,ok,ok,ok,ok,ok,ok] 11> [scorer:add_score(G_b, 20 + rand:uniform(9), 1.0) || _ <- lists:seq(1, 9)]. [ok,ok,ok,ok,ok,ok,ok,ok,ok]

After that, we can get the best and the worse ones from the specified pool: erl 12> Best3_A = scorer:top(P_a, 3). [{100.0,john},{2.0,17},{2.0,14}] 13> Worst3_A = scorer:bottom(P_a, 3). [{1.0,11},{1.0,13},{1.0,19}]

If we query the pool p_ab we will get the scores of all the groups together: erl 14> Best3_All = scorer:top(P_ab, 3). [{100.0,john},{3.0,24},{2.0,29}] 15> Worst3_All = scorer:bottom(P_ab, 3). [{1.0,11},{1.0,13},{1.0,19}]

Also it is possible to get the complete list sorted from lowest score to highest: erl 16> All = scorer:to_list(P_ab). [{1.0,11}, {1.0,13}, {1.0,19}, {1.0,23}, {1.0,27}, {2.0,12}, {2.0,14}, {2.0,17}, {2.0,28}, {2.0,29}, {3.0,24}, {100.0,john}]

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

Improvement ideas and requests

The main idea behind is to provide a flexible score system for other applications (for example evolutionary algorithms).

It is running behing mnesia to provide an automatic management of second index and transactions. However similar results might be achieved using 2 ets tables. Feel free tro try and discuss.

License

This software is under GPL-3.0 license.