A lossless file compression engine built in python

Author: aashumallik

Lossless file compression engine/compressor.py

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+import huffman
+import bitstring
+from bitstring import BitArray
+
+myfile = open("foo.txt","r") 
+allofthefile = myfile.read() 
+myfile.close() 
+
+mycharset = u"\u000A" 
+mycharset = mycharset + " abcdefghijklmnopqrstuvwxyz"+\
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"+\
+        "0123456789!#$%&'()\"*+,-./:;<=>?@[\]^_`{|}~"+\
+            "àæçèéêôëü" 
+countset = [0 for i in range (0,len(mycharset))] 
+
+for i in range (0,len(allofthefile)):
+    singlechar = allofthefile[i]
+    for j in range (0,len(mycharset)):
+        if mycharset[j] == singlechar:
+            countset[j] = countset[j]+1 # count the apperance of the charecters
+            break
+
+totalcount = 0
+for i in range (0,len(countset)):
+    totalcount = totalcount + countset[i] # count how many charecters text contains
+
+probabilityset = [0 for i in range (0,len(mycharset))] 
+
+for i in range (0,len(countset)):
+    probabilityset[i] = countset[i]/totalcount # calculate appearance probability of the charecters
+
+mydict = {} 
+
+for i in range (0, len(mycharset)):
+    if countset[i] != 0: # precaution to dont create a Huffman code for zero elements
+        mydict[str(mycharset[i])] = probabilityset[i] 
+mycodebook = huffman.codebook(mydict.items()) 
+
+
+for i in range (0,len(mycharset)):
+    if countset[i] != 0: # suppress the zero appearance charecters
+        print(mycharset[i] , " has " , '{0:04d}'.format(countset[i]) , " times appeared. "+\
+              "Probability = " , '{:.10f}'.format(probabilityset[i]) + " Huffman: " + mycodebook[str(mycharset[i])]) # just a print out operation
+
+onesandzeros = "" 
+for i in range (0, len(allofthefile)):
+    onesandzeros = onesandzeros + mycodebook[str(allofthefile[i])] 
+
+binary_file = open('compressed_foo.bin', 'wb') 
+
+i = 0
+while (i < len(onesandzeros)):
+    b = BitArray(bin=onesandzeros[i:i+8]) # divide array with 8 many bits and make them into a byte
+    b.tofile(binary_file) 
+    i = i+8
+
+binary_file.close()
+
+binary_file = open('compressed_foo.bin', "rb") 
+allofthebinaryfile = binary_file.read() 
+binary_file.close()
+
+newonesandzeros = "" 
+
+for i in range (0, len(allofthebinaryfile)):
+    newonesandzeros = newonesandzeros + str(bin(allofthebinaryfile[i])[2:].zfill(8)) # tranform bytes into bit array
+
+mynewfile = "" 
+i=0
+while (i < len(newonesandzeros)):
+    for j in range (0, len(list(mycodebook.values()))):
+        check = list(mycodebook.values())[j]
+        if (newonesandzeros[i:i+len(check)] == check): # check the Binary Huffman sequence in the bit array
+            mynewfile = mynewfile + list(mycodebook.keys())[j] # if the sequence is found, transform it into the character and add it to the character array
+            i = i + len(check)
+            break
+
+mynewfile = mynewfile[:-1] 
+
+newfile = open("foonew.txt","w") 
+newfile.write(mynewfile) 
+newfile.close() 
+