Entropy/Narcissist: Difference between revisions
Added Erlang version
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4.5129548515535785</lang>
=={{header|Erlang}}==
<lang erlang>#! /usr/bin/escript
-define(LOG2E, 1.44269504088896340735992).
main(_) ->
Self = escript:script_name(),
{ok, Contents} = file:read_file(Self),
io:format("My entropy is ~p~n", [entropy(Contents)]).
entropy(Data) ->
Frq = count(Data),
maps:fold(fun(_, C, E) ->
P = C / byte_size(Data),
E - P*math:log(P)
end, 0, Frq) * ?LOG2E.
count(Data) -> count(Data, 0, #{}).
count(Data, I, Frq) when I =:= byte_size(Data) -> Frq;
count(Data, I, Frq) ->
Chr = binary:at(Data, I),
case Frq of
#{Chr := K} -> count(Data, I+1, Frq #{Chr := K+1});
_ -> count(Data, I+1, Frq #{Chr => 1})
end.
</lang>
{{out}}
<pre>
My entropy is 5.00988934931771
</pre>
=={{header|FreeBASIC}}==
<lang FreeBASIC>' version 01-06-2016
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