Python 3 programming | Computer Science homework help

File Encryptions and Decryption


Write a program that uses a director to assign “codes” to each letter of the alphabet, for example:

Codes = {‘A’: ‘%’, ‘a’: ‘9’, ‘B’: ‘@’,’b’: ‘#’. Etc…}

Using this example, the letter A would be assigned the symbol %, the letter a would be assigned the number 9, the letter B would be assigned the symbol @, and so forth.

The program should open a specified text file, read it contents, and then use the dictionary to write an encrypted version of the file’s contents to a second file. Each character in the second file should contain the code for corresponding character in the first file.

Write a second program that opens an encrypted file and display its decrypted contents on the screen.


Word Frequency

Write a program that reads the contents of a text file. The program should create a dictionary in which the keys are the individual words found in the file and the values are the number of times each word appears. For example, if the word “The” appears 128 times, the dictionary would contain an element with ‘the’ as the key and 128 as the value. The program should either display the frequency of each word or create a second file containing a list of each word and its frequency.


There are “Programming Exercises” for Chapter 9 on pages 415-418 in the course text.

Your assignment is to write programs for Exercise 3 and Exercise 5. For both exercises, use the text file namedfor_chapter9.txt. This file is provided in a zip above the drop box for this assignment.


Create a folder that identifies you and Assignment 3 such as smith_asst3 or asst3_jones. Save all Python programs to this folder. Zip the folder. No .rar files allowed. Upload the zip to the Assignment 3 drop box.

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