比如 列表[1,1,1,1,2,2,2,4,4,4,4,4,4,3,3,5,6,6,6] 处理成
[5,3,3,2,2,2,6,6,6,1,1,1,1,4,4,4,4,4,4]

% -export([sort/1]).

-compile(export_all).

get_map(List) ->

lists:foldl(

fun(X, Map1) ->

% io:format("new map is ~p~n", [Map1]),

case maps:find(X, Map1) of

error ->

% io:format("before add map is ~p~n", [Map1]),

maps:put(X, 1, Map1);

{ok, Value} ->

% io:format("before update map is ~p~n", [Map1]),

maps:update(X, Value + 1, Map1)

end

end, #{}, List).

sort(List) ->

Map = get_map(List),

List1 = maps:to_list(Map),

List2 = lists:keysort(2, List1),

List4 = lists:foldl(

fun({Key, Value}, List3) ->

[lists:duplicate(Value, Key) | List3]

end, [], List2),

lists:flatten(lists:reverse(List4)).
test_sort() ->

List = [1,1,1,1,2,2,2,4,4,4,4,4,4,3,3,5,6,6,6],

sort(List).


测试：



1> c(sort_by_times).

{ok,sort_by_times}

2> sort_by_times:test_sort().

[5,3,3,2,2,2,6,6,6,1,1,1,1,4,4,4,4,4,4]

3> sort_by_times:get_map([1,1,3,3,3,3,2,2,2,2,2,6,6,6]).

{1 => 2,2 => 5,3 => 4,6 => 3}
4> Map =sort_by_times:get_map([1,1,3,3,3,3,2,2,2,2,2,6,6,6]).
{1 => 2,2 => 5,3 => 4,6 => 3}
5>