Autodetect Charset

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Andrey Klimov (2003-10-31 18:28) [0]

Кто-нибудь знает алгоритм автоматического определения кодировки (koi8-r, win-1251, ....) ?

Как, например, АВТОМАТИЧЕСКИ узнать в какой кодировке строка " "вЙЪОЕc Ч УФЙМЕ жAоK" - кПОБc PЙДДeТУФТПМЕ, 22 ПЛФСВТС УЗП ЕБЩПВД"......

АВТОМАТИЧЕСКИ...

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Reindeer Moss Eater (2003-10-31 18:34) [1]

Статистический метод

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vuk (2003-10-31 19:45) [2]

Имеется в виду определение кодировки по частоте встречаемости символов (или пар символов) с определенными кодами.

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Dimaxx (2003-10-31 23:15) [3]

type
TCodePage = (cpWin1251, cp866, cpKOI8R);

PMap = ^TMap;
TMap = array [ #$80..#$FF] of Char;

function GetMap(CP: TCodePage): PMap;
{ должна возвращать указатель на таблицу перекодировки из CP в Windows1251 (nil для CP = cpWin1251) }
begin
GetMap:=nil;
end;

function DetermineRussian(Buf: PChar; Count: integer): TCodePage;
const ModelBigrams: array [0..33,0..33] of Byte = ({АБВГДЕЖЗИЙКЛМHОПРСТУФХЦЧШЩЪЫЬЭЮЯ_Ё}
{А}(0,20,44,12,22,23,16,60,4,9,63,93,47,110,0,16,35,61,81,1,5,13,24,17,12,4,0,0,0,0,14,31,205,1),
{Б}(19,0,0,0,4,19,0,0,8,0,2,15,1,4,41,0,15,5,0,15,0,2,1,0,0,6,16,37,0,0,0,4,
{В}(97,0,1,0,2,57,0,5,40,0,4,25,2,23,78,2,8,28,4,12,0,1,0,0,8,1,0,40,1,0,0,5,106,3),
{Г}(13,0,0,0,9,5,0,0,15,0,1,17,1,2,96,0,24,0,0,7,0,0,0,0,0,0,0,0,0,0,0,0,8,0),
{Д}(63,0,9,1,2,71,1,0,35,0,3,16,2,22,50,2,19,9,2,25,0,2,1,0,1,0,1,9,4,0,1,5,
{Е}(4,14,15,34,56,22,13,14,2,34,39,77,73,150,6,9,101,64,81,1,0,15,5,12,10,6,0,0,0,0,3,4,235,1),
{Ж}(13,0,0,0,12,47,0,0,16,0,1,0,0,23,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,2,2),
{З}(76,2,11,3,11,4,1,0,7,0,2,4,11,24,17,0,6,1,0,8,0,0,0,0,0,0,0,16,6,0,1,4,1,
{И}(7,9,32,5,18,60,4,42,31,27,28,46,55,49,12,7,26,60,53,0,5,25,14,28,4,1,0,0,0,0,9,56,255,0),
{Й}(0,0,0,0,2,0,0,0,0,0,1,3,0,3,0,0,0,10,3,0,0,0,0,1,1,0,0,0,0,0,0,0,122,0),
{К}(92,0,3,0,0,7,2,1,39,0,0,27,0,14,110,0,18,5,35,18,0,0,11,0,0,0,0,0,0,0,0,0,5,5,0),
{Л}(85,1,0,2,1,70,6,0,85,0,5,3,0,9,67,1,0,9,0,15,0,0,0,2,0,0,0,9,66,0,15,43,
{М}(44,0,0,0,0,65,0,0,47,0,1,1,10,15,57,7,0,2,0,24,0,0,0,0,0,0,0,28,0,0,0,8,
{}(139,0,0,1,11,108,0,4,152,0,7,0,1,69,161,0,0,8,25,24,5,1,5,2,0,1,0,83,10,0,1,29,38,5),
{О}(0,72,139,76,74,32,32,19,12,52,21,93,68,72,7,34,93,102,98,1,2,6,6,19,15,2,0,0,0,1,4,9,252,2),
{П}(17,0,0,0,0,43,0,0,14,0,1,9,0,1,125,3,120,1,2,8,0,0,0,0,0,0,0,3,6,0,0,3,2,2),
{Р}(151,1,6,4,3,103,7,0,76,0,4,0,11,10,117,1,0,5,9,39,2,5,0,1,3,0,0,24,7,0,1,10,22,5),
{С}(24,1,21,0,3,39,0,0,33,0,56,41,11,15,58,30,5,30,183,16,0,4,1,4,1,0,0,8,25,0,1,50,41,2),
{Т}(83,0,43,0,3,87,0,0,71,0,9,3,2,26,180,0,55,33,1,23,1,0,1,4,0,0,0,20,78,0,0,5,82,4),
{У}(3,6,7,14,19,8,13,6,0,1,13,15,10,7,0,12,17,16,19,0,1,3,0,12,5,8,0,0,0,0,2,
{Ф}(4,0,0,0,0,4,0,0,11,0,0,1,0,0,9,0,3,0,0,4,1,0,0,0,0,0,0,0,0,0,0,0,2,0),
{Х}(9,0,2,0,0,2,0,0,5,0,0,1,0,5,26,0,4,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,76,0),
{Ц}(5,0,0,0,0,16,0,0,48,0,1,0,0,0,4,0,0,0,0,3,0,0,0,0,0,0,0,2,0,0,0,0,3,0),
{Ч}(30,0,0,0,0,52,0,0,23,0,3,1,0,14,1,0,0,0,36,5,0,0,0,0,1,0,0,0,1,0,0,0,2,2),
{Ш}(13,0,0,0,0,28,0,0,17,0,4,4,0,4,3,0,0,0,1,3,0,0,0,0,0,0,0,0,3,0,0,0,1,1),
{Щ}(6,0,0,0,0,23,0,0,16,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,1),
{Ъ}(0,0,0,0,0,16,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0),
{Ы}(0,5,14,1,3,28,0,2,0,22,6,19,21,2,0,5,4,7,10,0,0,37,0,3,4,0,0,0,0,0,0,1,8,
{Ь}(0,1,0,0,0,9,0,10,1,0,13,0,2,26,0,0,0,10,3,0,0,0,1,0,6,0,0,0,0,0,6,4,117,0),
{Э}(0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,31,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0),
{Ю}(0,5,0,0,3,0,0,0,0,0,0,1,0,0,0,0,0,1,15,0,0,0,1,4,1,15,0,0,0,0,0,0,38,0),
{Я}(0,0,9,2,7,10,3,19,0,0,1,6,7,8,0,0,2,6,19,0,0,3,5,1,0,3,0,0,0,0,5,2,177,0),
{_}(42,80,193,43,109,41,18,53,159,0,144,27,83,176,187,229,70,231,99,47,15,13,6,58,7,0,0,0,0,38,0,22,0,2),
{Ё}(0,0,0,0,3,0,0,0,0,0,2,4,4,8,0,0,5,3,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0));

{ "рейтинг" буквы Ё условно принимается равным 1/20 от "рейтинга" буквы E, если сочетание с участием Ё корректно, иначе - 0 }

type
TVariation = array[0..33,0..33] of integer;

var I,J,iC,iPredC,Max: integer;
C: Char;
CP: TCodePage;
D,MinD,Factor: double;
AMap: PMap;
PV: ^TVariation;
Vars: array[TCodePage] of TVariation;
begin
DetermineRussian:=cpWin1251; { по yмолчанию }
{ вычисление распределений биграмм }
FillChar(Vars,sizeof(Vars),0);
for CP:=Low(Vars) to High(Vars) do
begin
AMap:=GetMap(CP);
PV:=@Vars[CP];
iPredC:=32;
for I:=0 to pred(Count) do
begin
C:=Buf[I];
iC:=32;
if C>=#128 then
begin
if AMap<>nil then C:=AMap^[C];
if not (C in ["Ё","ё"]) then
begin
C:=Chr(Ord(C) and not 32);
{"a".."я"->"А".."Я"}
if C in ["А".."Я"] then iC:=Ord(C)-Ord("А");
end
else iC:=33;
end;
Inc(PV^[iPredC,iC]);
iPredC:=iC;
end;
end;
{ вычисление метрики и определение наиболее правдоподобной кодировки }
MinD:=0;
for CP:=Low(Vars) to High(Vars) do
begin
PV:=@Vars[CP];
PV^[32,32]:=0;
Max:=1;
for I:=0 to 33 do
for J:=0 to 33 do if PV^[I,J]>Max then Max:=PV^[I,J];
Factor:=255/Max; { ноpмализация }
D:=0;
for I:=0 to 33 do
for J:=0 to 33 do D:=D+Abs(PV^[I,J]*Factor-ModelBigrams[I,J]);
if (MinD=0) or (D<MinD) then
begin
MinD:=D;
DetermineRussian:=CP;
end;
end;
end;

begin
{ тест: слово "Пример" в разных кодировках (веpоятность ошибок на таких коpотких текстах высока - в данном слyчае пpосто повезло!) }
writeln(DetermineRussian(#$CF#$F0#$E8#$EC#$E5#$F0, 6) = cpWin1251);
writeln(DetermineRussian(#$8F#$E0#$A8#$AC#$A5#$E0, 6) = cp866);
writeln(DetermineRussian(#$F0#$D2#$C9#$CD#$C5#$D2, 6) = cpKOI8R);
readln;
end.

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