MATLAB: Grading MATLAB assignments automatically

distance_learninggradegradinghomeworkinputinstructormatlab_grader

Hi Everybody,

I had a kind of an odd question, as part of my job, I am required to grade 80 students MATLAB functions and scripts. Being the optimizing engineering student I hope to resemble, I thought there could be an easier way to do this than by examining all their code by hand and running each test automatically. Parsing certain sections of code would be really easy, but one of my questions I have been pondering is in regards to input.

I was wondering if there would be a way to have a script (GradingScript) run a different script (StudentScript) and have the GradingScript automatically provide arguments for the standard input prompts (response=input('Enter response: '); )

I know there are many ways around this, but I was curious if there was any way to actually do that.

Also, if you have any other ideas of how to grade introductory matlab assignments automatically, that would be awesome!

Thanks, Shaun

Best Answer

When I took programming classes in the past, the professor would specify what the function/method/CLI was supposed to look like and then use that to check results using a framework of their design. A big theme was that you should be able to program to a specified API without knowing who was calling you and give the correct result.

There would be sample inputs and outputs, for example "bar is 10 with the following four inputs", e.g.

bar = foo(1,2,4,5)

So your automation would just need to put your test case driver and the student's code in the same place and call them, or modify the path, etc. I also agree with Daniel that avoiding input is generally a better way to do programming. If they want to run tests interactively, that's fine, but it's far easier to do things like

bar = foo(0,0,0,0)
bar = foo(1,3,4,5)
bar = foo(10,10,10,10)
bar = foo(-4,5,0,1)

and just check that the output is correct rather than entering it manually every time. It also opens the door to using other input methods (GUI, the interactive prompt, some other program, an instrument, etc)

It would probably be a good idea to run a diff of each file versus all the others and catch the especially lazy cheaters.

I also agree with Jan that it's important to critique and review the code. Design review is a very real part of engineering, and they should get used to having other people review their code for aspects that are difficult or impossible to check automatically -- maintainability, readability, ease of debugging and so on.

Related Solutions

MATLAB: Is there a good way to get Cody Coursework results to other grading programs

http://www.mathworks.com/matlabcentral/fileexchange/60002-codygrades This file should work!

MATLAB: How to hide the Cody Coursework Test Suite from Students

First, we need to understand why MathWorks has made the Test Suite visible to students. Students are encouraged to use MATLAB on their computer to solve problems. To make this possible, students must be able to copy and paste the Test Suite code into a MATLAB script which, in turn, calls their solution function. Once satisfied, they then copy their solution function into Cody Coursework for assessment. For this reason, if your real concern regards student attempts to cheat the system, please first try the information offered here before using the approach discussed below.

If you're still determined to hide the test suite, I'd recommend hiding some and leaving some public.

First, compile a MATLAB function containing test suite code you'd like hidden as Protected MATLAB code.

Second, post this .p file somewhere online accessible by Cody Coursework. This must not be behind the school's firewall, it must be publicly accessible. One option is to use the public folder of a free dropbox account. If using DropBox, it will help to "copy the public link" using their web interface.

Third, implement a test case of your test suite to call your protected test suite function, for example:

   %%Execute Hidden Tests
   urlwrite('http://url/ProfsFunction.p','./ProfsFunction.p');
   rehash
   assert(ProfsFunction());

Fourth, add a test case to prevent student attempts to call on the .p file themselves, for example by parsing the students' solution file directly,

   %%Test for attempts to cheat
   found = 0;
   fid = fopen('StudentsFunction.m');
   while(~feof(fid))
      s = fgetl(fid);
      k = regexp(s,'urlwrite\(|ftp\(|mget\(|web\(|fprintf\(|fwrite\(|sprintf\(');
      if ~isempty(k)
          found = 1;
      end
   end
   fclose(fid);
   assert(isequal(found,0))

Fifth, use the solution map as a "line of last defense." Typically, honest solutions which are correct follow similar patterns. Horizontal bars of these patterns form on the solution map. The few stray solutions below these bars which Cody Coursework has marked correct merit manual code inspection.

There are many possibilities the power of the MATLAB language offers for implementing test suites. We will add more information and examples in future, and I encourage you to share your own insights as answers or comments below.

Best Answer

Related Solutions

MATLAB: Is there a good way to get Cody Coursework results to other grading programs

MATLAB: How to hide the Cody Coursework Test Suite from Students

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