The python script ("check_prefix_codes.py") will read a sequence of codewords from a file and validate if the code is a prefix code. The file "codes.txt" is an example input file.

Write a new script that will read two files

1. A file containing the codewords (like codes.txt)
2. A file containing the sequence of 1s and 0s representing a compressed file, compressed using the code read from the file.

Your script should first validate if the read code is a prefix code, and then use these codewords to decode the second file. (You can assign arbitrary symbols to each codeword).

Put your results and example inputs and outputs in a .pdf file, and submit your scripts along with the example input file(s) used.

codes.txt:

00

01

10

110

111

check_prefix_codes.py:

import numpy as np

class node:

left = None

right = None

isLeaf = False

#read all the codewords from the file

with open('codes.txt', 'r') as inp:

codewords = inp.read().splitlines()

#instantiate the tree

root = node()

for codeword in codewords:

#traverse the tree according to code bits, if you reach a leaf while traversing, output No

marker = root #start from the root

for codebit in codeword:

if marker.isLeaf: #check if marker is a leaf

print("No, the code is not a prefix code")#if yes, output No

quit()else:

if codebit == '0':#if codebit is 0, go left, build if necessary

if marker.left == None: marker.left = node()

marker = marker.left

if codebit == '1':#if codebit is 1, go right, build if necessary

if marker.right == None: marker.right = node()

marker = marker.right

marker.isLeaf = True#make the end point a leaf

print('Yes, the code is a prefix code')

lengths = np.array([len(codeword) for codeword in codewords])

lMean = np.mean(lengths)

print('the average length is %f'%lMean)