source code
% The Computer Language Benchmarks Game
% https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
%% contributed by Fredrik Svahn based on an earlier submission
%% by Kenneth Johansson, Vlad Dumitrescu and Ulf Wiger
-module(knucleotide).
-export([main/1]).
to_upper(<<C, Cs/binary>>, Acc) when C >= $a, C =< $z ->
to_upper(Cs, [C-($a-$A)| Acc]);
to_upper(<<$\n, Cs/binary>>, Acc) -> to_upper(Cs, Acc);
to_upper(<<C, Cs/binary>>, Acc) -> to_upper(Cs, [C | Acc]);
to_upper(<<>>, Acc) -> lists:reverse(Acc).
%% Read and discard until start of third segment
seek_three() ->
case io:get_line('') of
<<">TH", _/binary>> -> done;
eof -> erlang:error(eof);
_ -> seek_three()
end.
%% Read third segment
get_seq_three(Seq) ->
case io:get_line('') of
eof -> iolist_to_binary(lists:reverse(Seq));
Str -> get_seq_three([to_upper(Str, [])|Seq])
end.
%% Generate frequency hash table
gen_freq_table(FreqT, Seq, Len) ->
gen_freq_table(Seq, Len, FreqT, size(Seq)-Len).
gen_freq_table(_, _, _, -1) -> done;
gen_freq_table(Seq, Len, FreqT, Dec) ->
<<_:Dec/binary, Key:Len/binary, _/binary>> = Seq,
update_counter(Key, FreqT),
gen_freq_table(Seq, Len, FreqT, Dec-1).
%% Update hash table counter for already existing pattern or insert new
update_counter(Key, FreqT) ->
try ets:update_counter(FreqT, Key, 1) of _ -> ok
catch error:badarg -> ets:insert(FreqT, {Key, 1})
end.
%% Print the frequency table in the right order
print_freq_table(FreqT) ->
FreqList = lists:reverse(lists:keysort(2, ets:tab2list(FreqT))),
Tot = lists:foldr(fun({_, Cnt}, Acc)-> Acc + Cnt end, 0, FreqList),
lists:foreach(fun({Nucleoid, Cnt})->
io:fwrite("~s ~.3f\n",[Nucleoid, Cnt*100/Tot])
end, FreqList),
io:fwrite("\n").
%% Print number of occurrences for a specific pattern
print_count(FreqT, Pattern) ->
case ets:lookup(FreqT, Pattern) of
[{_, Value}] -> io:fwrite("~w\t~s\n",[Value, Pattern]);
[] -> io:fwrite("~w\t~s\n",[0, Pattern])
end.
%% Spawn a worker process with its own hash table
do({PrintFun, Pattern}, Seq) ->
spawn( fun()->
FreqT = ets:new(hash, [set]),
gen_freq_table(FreqT, Seq, size(Pattern)),
%Work is done, wait for token and print
receive Pids ->
PrintFun(FreqT, Pattern),
hd(Pids) ! tl(Pids)
end,
ets:delete(FreqT)
end ).
main(_Arg) ->
io:setopts(standard_io, [binary]),
seek_three(),
Seq = get_seq_three([]),
PrintFreq = fun(Res, _Pattern)-> print_freq_table(Res) end,
PrintCount = fun(Res, Pattern)-> print_count(Res, Pattern) end,
Actions = [{PrintFreq, <<"?">>},
{PrintFreq, <<"??">>},
{PrintCount, <<"GGT">>},
{PrintCount, <<"GGTA">>},
{PrintCount, <<"GGTATT">>},
{PrintCount, <<"GGTATTTTAATT">>},
{PrintCount, <<"GGTATTTTAATTTATAGT">>}],
Pids = [ do(Action, Seq) || Action <- Actions ],
%Pass token to print in right order
hd(Pids) ! tl(Pids) ++ [self()],
receive _Pid -> halt(0) end.