stats optimizations, thanks nygge
diff --git a/src/folsom_statistics.erl b/src/folsom_statistics.erl
index be8b0c2..eca0d8d 100644
--- a/src/folsom_statistics.erl
+++ b/src/folsom_statistics.erl
@@ -54,14 +54,12 @@
get_max([]) ->
0.0;
get_max(Values) ->
- [Head | _] = lists:reverse(lists:sort(Values)),
- Head.
+ lists:max(Values).
get_min([]) ->
0.0;
get_min(Values) ->
- [Head | _] = lists:sort(Values),
- Head.
+ lists:min(Values).
get_rate(Value1, Value2, Interval) ->
Delta = Value1 - Value2,
@@ -73,8 +71,12 @@
get_rate(Value1, Value2, Interval).
get_histogram(Values) ->
- Bins = [{Bin, 0} || Bin <- ?HIST],
- build_hist(Values, Bins).
+ Dict = lists:foldl(fun (Value, Dict) ->
+ update_bin(Value, ?HIST, Dict)
+ end,
+ dict:from_list([{Bin, 0} || Bin <- ?HIST]),
+ Values),
+ lists:sort(dict:to_list(Dict)).
% two pass variance
% results match those given by the 'var' function in R
@@ -102,8 +104,11 @@
Mean1 = folsom_statistics_scutil:arithmetic_mean(Values1),
Mean2 = folsom_statistics_scutil:arithmetic_mean(Values2),
Zip = lists:zip(Values1, Values2),
- List = [((X1 - Mean1) * (X2 - Mean2)) / length(Values1) || {X1, X2} <- Zip],
- lists:sum(List).
+ Samples = length(Values1),
+ lists:foldl(fun ({X1,X2}, Sum) ->
+ Sum + ((X1 - Mean1) * (X2 - Mean2)) / Samples
+ end,
+ 0, Zip).
get_kendall_correlation(Values, _) when length(Values) < ?STATS_MIN ->
0.0;
@@ -210,18 +215,7 @@
%%% Internal functions
%%%===================================================================
-% these histogram functions are too complicated, find better solution
-build_hist([Head | Tail], Hist) ->
- {Bin, Count} = proplists:lookup(which_bin(Head, Hist, []), Hist),
- List = proplists:delete(Bin, Hist),
- NewHist = lists:append(List, [{Bin, Count + 1}]),
- build_hist(Tail, NewHist);
-build_hist([], Hist) ->
- lists:sort(Hist).
-
-which_bin(Value, [{Bin, _} = B | Tail], Acc) when Value =< Bin ->
- which_bin(Value, Tail, lists:sort(lists:append(Acc, [B])));
-which_bin(Value, [_ | Tail], Acc) ->
- which_bin(Value, Tail, Acc);
-which_bin(_, [], [{Bin, _} | _]) ->
- Bin.
+update_bin(Value, [Bin|_Bins], Dict) when Value =< Bin ->
+ dict:update_counter(Bin, 1, Dict);
+update_bin(Values, [_Bin|Bins], Dict) ->
+ update_bin(Values, Bins, Dict).
