OPS435 Assignment 1 for Section B

Overview

When applying for a bank account, accepting a job, or some other activity that is personal, it may involve the processing of someone's date of birth. It is critical for this type of data to be validated before being processed by a computation system.

The task for this assignment is to design an algorithm and write a python script to validate a given string in various forms as the date of birth of someone and convert it into a standard format. The DOB conversion script should take a date in the following four formats: "YYYYMMDD", "YYYY/MM/DD", "YYYY-MM-DD", and "YYYY.MM.DD" format and return the date in a standard format: 'mmm d, yyyy", where "mmm" is the three letter abbreviated month's name, 'd' is a one or two-digit day of the month, and 'yyyy' is the four-digit year. That is, if the user enters "20201007", or "2020-10-07", or "2020/10/07", or "2020.10.07", the script will return "Oct 7, 2020". More examples to follow.

Assignment Requirements

The First Checkpoint (Oct 13)

• Before you begin coding in Python, it is important to plan your algorithm. Therefore your first task will be to complete and submit an algorithm document. This document should be named algorithm_[student_id].txt. This file should be plaintext. The document will contain two sections:

 * A description of how your main program works. The main program flow is provided to you in a1_template.py. Open the file, and use clear English to describe what each line of code does in such a way that a competent Python coder could reproduce the code without seeing it firsthand.
 * You will then apply the same principles to create an algorithm for each validation function named in the a1_template.py file. Inside the code, if you are calling another function like "leap_year()", you may simply describe what the function will return, and not the operation of the function itself. 

• This file should be submitted to Blackboard by Oct 13, 2020, and should be your first priority. The objective of the first checkpoint is not to have a 100% perfect algorithm, but to plan ahead and anticipate challenges and issues with the assignment. The first checkpoint will also allow your professor an opportunity to give you feedback before the assignment overall due date.
• Here is an basic introduction to Algorithm
• While you are working on the step-by-step instructions, note that there are different number of days in each month and some years have 365 days and some years have 366 days.
• Since we don't think we are going to encounter someone who is 120 years or older, your algorithm can consider a date of birth before year 1900 as invalid. Could you think of other limit you should put on someone's date of birth?

The 2nd Checkpoint - your drafted Python Script (Oct 16)

• As stated before, your code will be inside the file "a1_[Seneca_name].py". The first step will be to clone the Assignment 1 template repository (https://github.com/rayfreeping/ops435-a1). Once you clone the repository, run this command: "cp a1_template.py a1_[Seneca_name].py". (Replace Seneca_name with your Seneca account user name). Begin coding your algorithm into Python code that is required. Additional requirements are outlined below.
• Your should update the author and date information in your Python script.
• Your Python script file a1_[Seneca_name].py should be submitted to Blackboard by Oct 16, 2020. * The script doesn't have to be perfect and error free. However, it shouldn't contain any syntax errors when exectued.
• This intern submission is just to show that you are activity working on your assignment.

The 3rd Checkpoint - preliminary test results (Oct 20)

• Run the preliminary test script named "checkA1.py" in the "tests" sub-folder of the ops435-a1 repository mentioned above.
• Please read the readme.txt in the tests sub-folder for more information about the purpose of the preliminary test script.
• When your are satisfy with the test result, capture the test result to a file named a1_pretest.txt and submit it together with your Python script a1_[Seneca_name].py to Blackboard by Oct 20, 2020.

Python Coding Requirements

Required Modules and Functions

Your python script is allowed to call all the built-in functions and the functions imported from the os, subprocess and sys modules from the standard library.

Based on the algorithm you have designed for this assignment, you should at least have the following four functions defined in your python script (see later section on the purpose of each function):

• leap_year()
• size_check()
• value_check()
• usage()
• sanitize()

Coding Standard

Your python script must follow the following coding guide:

• PEP-8 -- Style Guide for writing Python Code

Command Line Argument to be supported

• Your Python script must support one command line argument only: date in the following format with correct values in YYYY, MM, and DD should be considered as valid input data:
  • YYYYMMDD
  • YYYY/MM/DD
  • YYYY-MM-DD
  • YYYY.MM.DD.
• If there are no argument, more than argument, or an invalid year, month, or day, your script should display the appropriate usage message, error code, and exit.

Documentation

• Please use python's docstring to document your python script
  • script level documentation, and
  • function level documention for each function you created for this assignment.
• The docstring should describe 'what' the function does, not 'how' it does.

Authorship Declaration

All your Python code for this assignment must be placed in a single source python file. Please complete the declaration as part of the docstring in your Python source code file (replace "Student Name" with your own name).

Github Commits

You will be graded partly on the quality and transaction activities of your Github commits. Professionals generally follow these guidelines:

• commit their code after every significant change,
• the code should run without syntax errors after each commit, and
• every commit has a descriptive commit message.

These guidelines are not always possible, but you are expected to follow these guidelines as much as possible. Break your problem into smaller pieces, and work iteratively to solve each small problem. Test your code after each small change you make, and address errors as soon as they arise. It will make your life easier!

Tests and Test results

You must name your python 3 script as a1_[Student_id].py. The following examples assumes that the student_id is rchan.The script should accept two command line arguments, the first one is the date in "YYYY-MM-DD" format, and the second one is the number of day from the given date, a positive value indicates the number of days after the given date, and a negative value indicates the number of days before the given date. There is an optional flag called --step which can be provided at the command line that makes the program print out all dates until the target date. If the "YYYY-MM-DD" format is broken, your script should give an appropriate error message. Invalid months (>12) or invalid days of month(different for each month), should be detected and give appropriate error messages. For examples:

• python3 a1_rchan.py 01-01-2019 02-01-2019, and the output should be
  

    1

• python3 a1_rchan.py 01-01-2019 31-12-2018, and the output should be
  

    -1

• python3 a1_rchan.py 01-06-2020, and since today is June 3, the output should be
  

    2 

• python3 a1_rchan.py 01-01-2019 01-01-2020, and the output should be
  

    365

• python3 a1_rchan.py 01-01-2021 01-01-2020 , and the output should be
  

    -366

• python3 a1_rchan.py 01-13-2018, and the output should be
  

    Error: wrong month entered

• python3 a1_rchan.py 99-01-2020 01-01-2020, and the output should be
  

    Error: wrong day entered

• python3 a1_rchan.py 2018 2, and the output should be
  

    Error: wrong date entered

If there is too few or too many command line arguments given, display the proper usage:

• Usage: a1_rchan.py DD-MM-YYYY [DD-MM-YYYY] >/code>

Script structure and sample template

The following is a brief description of each function:

• The dbda() function should be the main function of your script. The dbda() function will take two dates in "DD-MM-YYYY" format, and return an integer that corresponds to the number of days between the given dates. If the start date is earlier than the stop date, the number is positive. If start date is later than the stop date, the number is negative. Your dbda() function should delegate the actual calculation of the target date to either the after() function or the before() function.
• The today() function will be called if the user has not specified a second argument. It will return your Linux computer's local time in the format DD-MM-YYYY. Hint: you may need to read man pages for a shell command in order to return a usable date. You may also use string formatting to modify output.
• The before() function will take a date in "DD-MM-YYYY" format and return the date of the previous day in the same format.
• The after() function will take a date in "DD-MM-YYYY" format and return the date of the next day in the same format. Next paragraph is a sample python code for the after() function. To earn the maximum possible mark for the assignment, you should modify the sample after() function to make use of the days_in_mon() function.
• The leap_year() function will take a year in "YYYY" format, and return True if the given year is a leap year, otherwise return False.
• The valid_date() function will take a date in "DD-MM-YYYY" format, and return True if the given date is a valid date, otherwise return False plus an appropriate status message. The valid_date() function should make use of the days_in_mon() function.
• The days_in_mon() function will take a year in "YYYY" format, and return a dictionary object which contains the total number of days in each month for the given year. The days_in_mon() function should make use of the leap_year() function.
• The usage() function will take no argument and return a string describing the usage of the script.

Sample code for the after() function

# Return the date in DD-MM-YYYY after the given day
# 
def after(today):
    if len(today) != 10:
       return '00-00-0000'
    else:
       str_day, str_month, str_year = today.split('-')
       year = int(str_year)
       month = int(str_month)
       day = int(str_day)

       lyear = year % 4
       if lyear == 0:
          feb_max = 29 # this is a leap year
       else:
          feb_max = 28 # this is not a leap year

       lyear = year % 100
       if lyear == 0:
          feb_max = 28 # this is not a leap year

       lyear = year % 400
       if lyear == 0:
          feb_max = 29 # this is a leap year

       tmp_day = day + 1 # next day

       mon_max = { 1:31, 2:feb_max, 3:31, 4:30, 5:31, 6:30, 7:31, 8:31, 9:30, 10:31, 11:30, 12:31}
       if tmp_day > mon_max[month]:
          to_day = tmp_day % mon_max[month] # if tmp_day > this month's max, reset to 1
          tmp_month = month + 1
       else:
          to_day = tmp_day
          tmp_month = month + 0

       if tmp_month > 12:
           to_month = 1
           year = year + 1
       else:
           to_month = tmp_month + 0

       next_date = str(to_day)+"-"+str(to_month).zfill(2)+"-"+str(year).zfill(2)
     
       return next_date

Rubric

Task	Maximum mark	Actual mark
Program Authorship Declaration	5
Check script passed	30
today() function design	2
before() function design	5
dbda() function design	10
script level docstring	5
leap_year() function design	2
valid_date() function design	5
usage() function design	1
First Milestone	10
Reflection Essay	10
github.com repository: Commit messages and use	15
Total	100

Due Date and Final Submission requirement

Check with your professor for the due date for your section.

Please submit the following files by the due date:

• [ ] your algorithm document, named as 'algorithm_username.txt', to Blackboard.
• [ ] your python script, named as 'a1_[seneca-id].py', should be included in your repository, and also submitted to Blackboard.
• [ ] the output of the checking script checkA1.py, named as 'a1_output.txt', should be included in your repository.
• [ ] your debrief document should be submitted to Blackboard.