Custom concatenation of inner list Erlang

Question 1

I propose you this solution:

[edit]

I modified the code to answer your last comment, there are still fuzzy things:

if Assets are different, creates different record list?
if not what should be done with Asset name? I have chosen to keep the "smallest one"
is the order of records important - I decided no

One remark, I am missing some context, but If I add to collect such informations, I would store it in an ets table. It is faster to update, easy to traverse, and easy to transform into list if needed.

-module (t).

-compile([export_all]).

%      rec = {atom,term}
%      reclist = [rec,...]
%      asset = {bin,reclist}
%      eval_data = [{list,asset}]
%      eval_set = [eval_data,...]
%      recs = {atom,[term]}
%      recslist = [recs,...]

addrec({Key,Val},Recslist) ->
    Val_list = proplists:get_value(Key, Recslist, []),
    [{Key,[Val|Val_list]}|proplists:delete(Key,Recslist)].

merge_rec(Reclist,Recslist) -> lists:foldl(fun(Rec,Acc) -> addrec(Rec,Acc) end,Recslist,Reclist).


merge_eval([{Eval,{Asset,Reclist}}],[]) ->
    [{Eval,{Asset,[{Key,[Val]} || {Key,Val} <- Reclist]}}];
merge_eval([{Eval,{Asset,Reclist}}],[{Eval_low,{Asset_low,Recslist}}]) ->
    [{min(Eval,Eval_low),{min(Asset,Asset_low),merge_rec(Reclist,Recslist)}}].

merge_set(Eval_set) -> lists:foldl(fun(Eval_data,Acc) -> merge_eval(Eval_data,Acc) end,[],Eval_set).

test() ->
    Eval_set =  [[{"eval_data_10",
                {<<"prvl_mobable_asset_0000_h200401">>,
                 [{'F_01_0100',[1]},
                  {'F_01_0090',["3"]},
                  {'F_01_0080',[]},
                  {'F_01_0070',[9999]},
                  {'F_01_0060',[{era,0},{year,[]},{month,[]}]},
                  {'F_01_0050',[]},
                  {'F_01_0040',[]},
                  {'F_01_0030',[]},
                  {'F_01_0020',<<>>},
                  {'F_01_0010',<<"4 - 8">>}]}}],
              [{"eval_data_11",
                {<<"prvl_mobable_asset_0000_h200401">>,
                 [{'F_01_0100',[]},
                  {'F_01_0090',["2"]},
                  {'F_01_0080',[]},
                  {'F_01_0070',[22222]},
                  {'F_01_0060',[{era,0},{year,[]},{month,[]}]},
                  {'F_01_0050',[]},
                  {'F_01_0040',[]},
                  {'F_01_0030',[]},
                  {'F_01_0020',<<>>},
                  {'F_01_0010',<<"4 - 1">>}]}}]],
    merge_set(Eval_set).

Question 2

@trex:

FormList = [[{EVAL_SEQ_1, {FORMNAME, ListDataToConcat1}}], [{EVAL_SEQ_2, {FORMNAME, ListDataToConcat2}}], ....]

You will need to get a separate the list which has common form names as <<"prvl_mobable_asset_0000_h200401">>

{MobableList, EvalDataList} = lists:partition(fun([{EVAL_SEQ, {FORMNAME, ListData}}]) -> 
            FORMNAME == <<"prvl_mobable_asset_0000_h200401">>
         end, FormList),

Then, Get a separate Tuple of Form sequences and Lists. To separate them

{EvalSeq, MergingList} = lists:foldl(fun(X, {EvalNames, OutList}) -> 
                [{EVAL_SEQ, {FORMNAME, ListData}}] = X,
                {[EVAL_SEQ|EvalNames], [ListData|OutList]}
             end, {[], []}, MobableList),

Hence, you will get the new tuple as :

{[EVAL_SEQ_1, EVAL_SEQ_2, EVAL_SEQ_3, ...], [ListDataToConcat1, ListDataToConcat2, ListDataToConcat3,...]}

I'm not sure which sequence Number you want as you havn't mentioned it clearly, Here is the way you can get the minimum Sequence Number. Evalsequence = lists:min(EvalSeq),

Now merge your code using merge function as shown below or you can refer merging inner list Merge inner lists of a list erlang:

    MergedList = merge(MergingList),

And finally a separate list as:

[{Evalsequence, {<<"prvl_mobable_asset_0000_h200401">>, MergedList}}].


merge(ListOfLists) ->
        Combined = lists:append(ListOfLists),
        Fun      = fun(Key) -> {Key,proplists:get_all_values(Key,Combined)} end,
        lists:map(Fun,proplists:get_keys(Combined)).