From 7bb66b1dd26b04b58b39a43632ea107313307b66 Mon Sep 17 00:00:00 2001
From: Tomas Musil <tomik.musil@gmail.com>
Date: Wed, 4 Apr 2012 23:59:56 +0200
Subject: [PATCH] ted to vypada, ze je nejlepsi cislo 4

---
 jakobsen4.py | 101 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 test         |   2 ++
 2 files changed, 103 insertions(+)
 create mode 100644 jakobsen4.py
 mode change 100644 => 100755 test

diff --git a/jakobsen4.py b/jakobsen4.py
new file mode 100644
index 0000000..38b9a84
--- /dev/null
+++ b/jakobsen4.py
@@ -0,0 +1,101 @@
+"""Modul pro praci s Jakobsenovym algoritmem."""
+
+from itertools import combinations
+import pickle
+from ocesavac import ocesat
+from spolecne import MABECEDA
+
+def nova_tabulka(zprava, abc=MABECEDA):
+    """Vraci tabulku cetnosti bigramu ve zprave nad danou abecedou."""
+    tabulka = dict()
+    for i in abc:
+        tabulka[i] = dict()
+        for j in abc:
+            tabulka[i][j] = 0
+    for i in range(len(zprava) - 1):
+        tabulka[zprava[i]][zprava[i+1]] += 1
+    celkem = sum(sum(tab2.values()) for tab2 in tabulka.values())
+    for i in abc:
+        for j in abc:
+            tabulka[i][j] /= float(celkem)
+    return tabulka
+
+def vzdalenost(tab1, tab2, abc=MABECEDA):
+    """Vraci soucet strednich kvadratickych odchylek pro dve tabulky cetnosti
+    bigramu nad danou abecedou."""
+    rozdil = 0
+    for i in abc:
+        for j in abc:
+            rozdil += abs(tab1[i][j] - tab2[i][j])
+    return rozdil
+
+def substituce(zprava, slovnik):
+    """Vrati zpravu, ve ktere jsou znaky dane abecedy nahrazenypodle daneho
+    slovniku."""
+    pole = []
+    for char in zprava:
+        if char in slovnik:
+            pole.append(slovnik[char])
+        else:
+            pole.append(char)
+    return pole
+
+def poradi_dle_frekvence(zprava, abc=MABECEDA):
+    """Vrati znaky dane abecedy v poradi podle frekvence v dane zprave."""
+    freq = dict()
+    for char in abc:
+        freq[char] = 0
+    for char in zprava:
+        if char in abc:
+            freq[char] += 1
+    return sorted(freq.keys(), key=freq.get, reverse=True)
+
+class reference:
+    pass
+
+def jakobsen(zprava, ref):
+    """Pro danou sifrovanou zpravu vrati substitucni slovnik odvozeny s pomoci
+    Jakobsenova algoritmu s danou referencni tabulkou."""
+    slovnik = dict(zip(poradi_dle_frekvence(zprava, ref.abeceda), ref.poradi))
+    tabulka = nova_tabulka(
+                  substituce(zprava, slovnik),
+                  ref.abeceda
+                  )
+    vzdal = vzdalenost(tabulka, ref.tabulka, ref.abeceda)
+
+    vzdal_old = vzdal + 1
+    while vzdal_old > vzdal:
+        vzdal_old = vzdal
+        for (x, y) in combinations(ref.poradi, 2):
+            slovnik[x], slovnik[y] = slovnik[y], slovnik[x]
+            nova_vzdalenost = vzdalenost(
+                     nova_tabulka(
+                         substituce(zprava, slovnik),
+                         ref.abeceda),
+                     ref.tabulka,
+                     ref.abeceda)
+            if  nova_vzdalenost < vzdal:
+                vzdal = nova_vzdalenost
+            else:
+                slovnik[x], slovnik[y] = slovnik[y], slovnik[x]
+    return slovnik
+    
+
+def desifruj(zprava, mezery=True):
+    """Vrati vysledek pokusu dekodovat zpravu Jakobsenovym algoritmem."""
+    if mezery:
+        soubor = open('ref')
+    else:
+        soubor = open('bref')
+    ref = pickle.load(soubor)
+    soubor.close()
+    slovnik = jakobsen(ocesat(zprava, mezery), ref)
+    return '\n'.join([''.join(substituce(zprava, slovnik)),
+                      ' '.join(ref.abeceda),
+                      ' '.join([slovnik[c] for c in ref.abeceda])])
+
+def __test():
+    print desifruj('Mxbhfxn cbfbhinpr, wnx fv f gvzuyr cbenqv.'.upper())
+
+def __test2():
+    print desifruj('Sel pes do lesa a potkal dlazebni kostku. Chtelo by to jeste o neco delsi test, to tedy jo.'.upper())
diff --git a/test b/test
old mode 100644
new mode 100755
index 9136809..24caca8
--- a/test
+++ b/test
@@ -1,11 +1,13 @@
 #!/bin/bash
 
 echo "__test()" | python -i jakobsen.py
+echo "__test()" | python -i jakobsen4.py
 echo "__test()" | python -i jakobsen1.py
 echo "__test()" | python -i jakobsen2.py
 echo "__test()" | python -i jakobsen3.py
 
 echo "__test2()" | python -i jakobsen.py
+echo "__test2()" | python -i jakobsen4.py
 echo "__test2()" | python -i jakobsen1.py
 echo "__test2()" | python -i jakobsen2.py
 echo "__test2()" | python -i jakobsen3.py
-- 
2.4.2