18.7. Homework: Grade File

Copy project files in grade_file_homework_stub to your own project. Then you should have copies of the source file grade_files.cs for you to complete for this homework. The folder also contains sample data files including the examples discussed below.

In this assignment, we’re going to begin taking steps to help you achieve greater independence when it comes to programming. This means (among other things) that you will be given what is commonly known as a specification. In software development–and in the business world in general, it is customary to capture a set of business requirements in what is commonly known as a requirements specification document. While what you read here will be much more concise, we want you to become familiar with requirements-driven thinking, without which many real-world software projects fail.

After presenting the set of requirements, we will give you some hints for how to implement the requirements. These hints may or may not prove completely helpful to you, and you are also invited to come up with your own solutions. As we inch closer to the semester project, you’re going to want to use your imagination to create a good solution to a problem.

18.7.1. Brief Problem Statement

The previous two homework assignments represent a great simplification of the real-world process of grading. The notion that grade information must be entered manually is rather tedious, not to mention error prone. In the real world, grade information would be kept in a file (a spreadsheet is common), from which various calculations and summary reports could be generated.

In this assignment, the problem we are trying to solve is to take all of the raw grade data from one or more student files and prepare a summary report file with a line for each student.

Although we could do all of what we’re describing here with a spreadsheet, the point is to show how we can use C# to read in a simplified form of comma-separated data, process it, and do some general-purpose calculations on the data.

18.7.2. Using C#

We’ll be making use of a number of C# features (some old, some new) in this homework:

  • decisions, loops, strings, and functions
  • files
  • arrays

18.7.3. Requirements

  1. Unlike in previous assignments, this program must accept data from a collection of input files (that is, it will not be reading most of the data from the class Console).

  2. The program needs a course abbreviation from the user. If there is a command line argument, use it as the course abbreviation. Make sure your code can read a command-line argument using the special form of Main(string[] args) already in the stub grade_files.cs. If the user does not provide at command line argument, prompt the user for it once the program starts. An example would be comp170. All data files will include the course abbreviation as part of their name. We will use comp170 in the examples below, but it could be something else. The folder also contains sample data files for a course abbreviation comp150.

    Note that these data files are in the project directory. Make sure your project, like this stub, sets the Output Path to the project folder.

  3. There are two master files for any course. One is “categories_” + the course abbreviation + ”.txt”. For example, categories_comp170.txt is a sample data file provided and used below.

    It will contain three lines. The first line is a comma separated list of category names like

    Exam, Lab, Homework, Project, Class Participation
    

    There may be extra spaces after the commas. Categories will be chosen so that each one starts with a different letter.

    The second line contains the integer weights for each category, like

    40, 15, 15, 20, 10
    

    They do not need to add to 100. If the sum is called totWeights, get the final grade by summing for each category:

    (category weight)(category grade)/totWeights
    

    The third line will contain the number of grades in each category, like

    2, 5, 3, 1, 2
    

    The second master file will be “students_” + the course abbreviation + ”.txt”. For example students_comp170.txt. It will contain a list of student information records. Each record (one per input line) will have the following structure:

    Student ID, Last Name, First Name

    For example, the sample data file students_comp170.txt starts:

    P12345678, Doe, John
    P00000001, Hernandez, Maria
    
  4. There will be a secondary file for each student, named after the student id and the course abbreviation and ”.data”. For example, John’s scores would be kept in a file named P12345678comp170.data. Maria’s scores would be in P00000001comp170.data. Each record (one per file line will have the following structure:

    Category letter, Item, Points Earned

    where:

    • category letter is the first letter of the category. With the categories given in the example above, they would be E, L, H, P, and C.
    • item is a number within that category (1, 2, 3, ...) - only used in part of the extra credit.
    • points earned is a real number
    • the lines are in no special order.

    Sample data file P12345678comp170.data starts:

    H, 1, 90
    C, 1, 100
    L, 3, 100
    L, 2, 80
    H, 2, 80
    E, 1, 90
    
  5. The program will process the data from each student file and calculate the average within each category, and then the weighted overall average. Also display the letter grade for each student, using code derived from the previous assignment.

  6. Your program writes the final report file. It is named with the course abbreviation + “_summary.txt”. Example: “comp170_summary.txt”. This file must have a line for each student showing the student’s last name, first name, weighted average rounded to one decimal place, and letter grade. File comp170_summary.txt would start with lines:

    Doe, John 78.9 C+
    Hernandez, Maria 88.2 B+
    

    Write this file to the same directory where you found the input data. Again the FIO Helper Class is useful.

  7. The rest of the test data for course abbreviations comp170 and all the data for comp150 is in the homework directory. There are also sample solution files for the summaries (including some extra credit additions at the ends of lines). Their names end in _solution.txt to distinguish them from the summary files you should generate in tests.

    While your program should certainly work for course abbreviations comp170 and comp150, it should also work in general for any data files your refer to in the defined formats and place in the same folder.

  8. Turn in materials as in the last homework, including a single copy of the homework source files and a log.txt file for each student, in the same form as for the last homework.

18.7.4. Hints

  1. Read Files, Paths, and Directories. You’re still going to need ReadLine() and WriteLine() in this assignment, the only difference is that we’ll get the input from a file instead of the Console. The parameter syntax will be the same.

  2. For each file line you’ll want to use the String Method Split, and then the Trim method from More String Methods on each part to remove surrounding spaces. Then use indexing to get the field of interest. (More below.)

  3. You’ll need an outer loop to read the records from the master name file. You’ll need an inner loop (or a loop inside of a function) to read the records for each student.

  4. When processing the records from a student file, you should process each one separately and not assumed they are grouped in any particular order.

    This means, specifically, that your program simply reads a record, decides what category it is in, and updates the running total for that category. Once the entire file has been read, you can compute the average for each category based on the number of items that should be in that category, which may be more than the number of records in the file for items turned in.

  5. There is no need to keep a score after you’ve read it and immediately used it. Do use an array, however, for the running total for each category.

  6. In order to deal with a varying number of categories and different possible first letter codes, you will need to split the category name line into an array, say

    string[] categories;
    

    To know where to update data for each category, you can use this function after you read in a code, to determine the proper index. It is already in the stub of the solution file grade_files.cs:

          /// Take the first letter code for a catagory, and
          /// return the index of that category in categories.
          static int codeIndex(string code, string[] categories)
          {
             for (int i = 0; i < categories.Length; i++) {
                if (categories[i].Trim().StartsWith(code)) {
                   return i;
                }
             }
             return -1; //required by compiler: shouldn't reach
          }
    

    You may assume the data is good and the -1 is never returned, but the compiler requires this last line.

  7. You cannot have one fixed formula to calculate the final weighted grade, because you do not know the number of categories when writing the code. You will have to accumulate parts in a loop.

  8. Test thoroughly! Be sure to test with and without command line parameter and with multiple data sets.

18.7.5. Grading Rubric (25 points)

  1. Get the abbreviation from the command line if it is there. [2]
  2. Otherwise get the abbreviation from prompting the user. [1]
  3. Read the categories file and parse lines. [2]
  4. Deal with each student. [3]
  5. Calculate the cumulative grades in each category, reading a student’s file once, using arrays. [5]
  6. Calculate the overall grade and letter grade. [3]
  7. Generate summary entries. [3]
  8. Use functions where there would otherwise be two several-line blocks of code differing only in the name of the data evaluated and the name of the result generated. [2]
  9. Use good style: formatting, naming conventions, meaningful names other than for simple array indices, lack of redundant code. [4]

Optional Extra Credit Opportunities! You may choose to do any combination that does not include both of the last two options about missing work.

  1. Format the summary file in nice columns. Include the grades for each category, rounded to one decimal place. Include a heading line. For example the summary for the repository example Comp150 could start:

    Name: Last, First           Avg Gr     E     H     P
    Hopper, Grace             100.0 A  100.0 100.0 100.0
    

    You may assume the last-first name field fits in 25 columns. Copy the first three column headings from above. The column headings for the categories can just be their one letter code. Names and letter grades should be left-justified (padded on the right, by using a negative field width). See Left Justification. [2]

  2. Change the scheme for calculating letter grades to use a function that calculates the proper grade, where the only if statement is one simple one inside a loop. The if statement will have a return statement in its body, and no else. The loop will need to use corresponding arrays of data for grade cutoffs and grade names. [3]

  3. For any student who has missed passing in all the required items, generate extra data on missing work in the summary, at the right end of the line for the student. Add this to whichever version of the earlier parts you use. Include an addendum starting with “Missing: ” only if there are not enough grades in one or more categories. For each category where one or more grades is missing, including a count of the number of grades missing followed by the category letter. An example using the example categories is:

    Doe, John 68.5 D+ Missing: 2 L 1 H
    Smith, Chris 83.2 B Missing: 1 L
    Star, Anna 91.2 A-
    

    meaning Doe has 2 labs missing and 1 homework missing. Smith is missing one lab. Star has done all assigned work, since nothing is added. The solution files display this extra credit addition on the ends of lines. [3]

  4. This is a much harder alternate version for handling missing work: Unlike the previous format, do not count and print the number of missing entries in each category in a form like “2 L ”. Replace such an entry with a list of each item missing, in order, as in “L:1, 4 ”, meaning labs 1 and 4 were missing. Assume that the expected item numbers for a category run from 1 through the number of grades in the category. You may assume no item number for the same category appears twice. For example, with the sample data files given in the repository for comp170, the summary line for John Doe would be:

    Doe, John 78.9 C+ Missing: L: 1, 4 H: 3
    

    The most straightforward way to do this requires something like an array of arrays, array of lists or array of sets. You may need to read ahead if you want to use one of these approaches. [5]