lab2

lesson_2/main.py

@@ -1,6 +1,7 @@
 import math
 import sys
 
+
 def index_to_bytes(value, bits):
     n = bits // 8
     if bits % 8 != 0:
@@ -19,12 +20,6 @@ def index_to_bytes(value, bits):
 sequence = list()
 
 outpath = sys.argv[2] if len(sys.argv) == 3 else sys.argv[1] + '.lzw'
-# cond ? a : b
-# a if cond else b
-# if len(sys.argv) == 3:
-#     outpath = sys.argv[2]
-# else:
-#     outpath = sys.argv[1] + '.lzw'
 with open(outpath, 'wb') as file:
     for sym in data:
         sequence.append(sym)
@@ -39,23 +34,13 @@ def index_to_bytes(value, bits):
 
         value = len(dictionary)
         dictionary[key] = value
-        # print(value, '->', key)
 
         sequence = sequence[-1:]
 
     n = math.ceil(math.log2(len(dictionary)))
     index_value = dictionary[tuple(sequence)]
     enc_value = index_to_bytes(index_value, n)
     file.write(enc_value)
-
-        # [1, 2, 3]
-        # [3]
-
-        # a
-        # a[b] -> [a] (ab) -> dict
-        # b[e] -> [b] (be) -> dict
-        # e
-
-        # a
-        # ab
-        # ab[c] -> [ab] (abc) -> dict
+for s in dictionary:
+    if dictionary[s] > 255:
+        print(s, "->", dictionary[s])

lesson_2/unmain.py

@@ -0,0 +1,76 @@
+import math
+import sys
+
+
+def amount_bytes(bits):
+    n = bits // 8
+    if bits % 8 != 0:
+        n += 1
+    return n
+
+
+if len(sys.argv) != 2:
+    print('Usage: python', sys.argv[0], 'input_file (output_file)')
+    exit(-1)
+
+path = sys.argv[1]
+outpath = sys.argv[1][:-4] + ".txt"
+
+with open(path, "rb") as file:
+    data = file.read()
+
+dictionary = {i: [i] for i in range(256)}
+pair = list()
+num = math.ceil(math.log2(len(dictionary)))
+num = amount_bytes(num)
+sym_a = b""
+first_el = True
+byte_num= 0
+with open(outpath, 'wb') as file:
+    while byte_num< len(data):
+        if first_el:
+            pair.append(list(dictionary[data[byte_num]]))
+            first_el = False
+            num = 2
+            byte_num+= 1
+            continue
+        if num > 0:
+            sym_a += data[byte_num].to_bytes(1, "little")
+            num -= 1
+            byte_num+= 1
+            continue
+        pair.append(list())
+        print(len(dictionary))
+        for j in dictionary[int.from_bytes(sym_a, "little")]:
+            pair[1].append(j)
+        dictionary[len(dictionary)] = list()
+        sym_a = b""
+        for i in pair[0]:
+            for j in dictionary[i]:
+                dictionary[len(dictionary) - 1].append(j)
+        dictionary[len(dictionary) - 1].append((dictionary[pair[1][0]][0]))
+        num = math.ceil(math.log2(len(dictionary)))
+        num = amount_bytes(num)
+        for i in pair[0]:
+            for j in dictionary[i]:
+                file.write(j.to_bytes(1, "little"))
+        pair = pair[1:]
+
+    pair.append(list())
+    for j in dictionary[int.from_bytes(sym_a, "little")]:
+        pair[1].append(j)
+    dictionary[len(dictionary)] = list()
+    sym_a = b""
+    for i in pair[0]:
+        for j in dictionary[i]:
+            dictionary[len(dictionary) - 1].append(j)
+    dictionary[len(dictionary) - 1].append((dictionary[pair[1][0]][0]))
+    num = math.ceil(math.log2(len(dictionary)))
+    num = amount_bytes(num)
+    for i in pair:
+        for z in i:
+            for j in dictionary[z]:
+                file.write(j.to_bytes(1, "little"))
+for e in dictionary:
+    if e > 255:
+        print(dictionary[e], "->", e)