encoder.py

# import sys
# from sys import argv

import shutil
from struct import *

def compression(ipt, fileName):
    input_file = ipt
    n = 64
    maximum_table_size = pow(2,int(n))      
    file = open(input_file)                 
    data = file.read()                      

    dictionary_size = 256                   
    dictionary = {chr(i): i for i in range(dictionary_size)}    
    string = ""             
    compressed_data = []    

    for symbol in data:                     
        string_plus_symbol = string + symbol 
        if string_plus_symbol in dictionary: 
            string = string_plus_symbol
        else:
            compressed_data.append(dictionary[string])
            if(len(dictionary) <= maximum_table_size):
                dictionary[string_plus_symbol] = dictionary_size
                dictionary_size += 1
            string = symbol

    if string in dictionary:
        compressed_data.append(dictionary[string])

    output_file = open(fileName + ".lzw", "wb")
    for data in compressed_data:
        output_file.write(pack('>H',int(data)))
        
    output_file.close()
    file.close()

    # -- move to directory
    current_path = "./" + fileName + ".lzw"
    new_path = "./compressed/" + fileName + ".lzw"

    shutil.move(current_path, new_path)

    return "Success"