CITS2401 Computer Analysis and Visualisation Semester 2, 2016
Assignment 2
Set date: 04 August 2016
Due date: Friday 5:00 pm, 07 October 2016 Total marks: 50
Assignment submission instructions:
• Submit 2 matlab files (Grading.m and PlotGrades.m) via the CITS2401 page on LMS (http://www.lms.uwa.edu.au).
• Put the files in a folder and rename it under filename: YourSurname_Studentnumber, e.g. Smith_902787889. Zip the folder using Windows Zipping/WinZip software. [Do not use 7-zip or winrar or any other zipping tools].
• If you are using windows platform in University labs then put the required file in a folder. Right click on
the folder and hover/click on “Send To” option, then click on “Compressed (zipped) folder”. This will
create a zip file. You may need to rename it as stated above.
• Submission guidelines must be strictly followed otherwise the grade may result in zero or penalized.
• You must name your functions and variables in the exact manner as mentioned in this assignment. Any variation will lead to penalized marks.
Plagiarism
All work submitted should be your own. I am sure that you agree that this is for your own good!! If you do not agree, please note that we have ways to detect plagiarism in code. Incidences of plagiarism will be taken seriously and will involve follow-up with the Head of School and consequences to academic results. . You can read the University policy on Academic Conduct here.
Question
Consider you have successfully completed the CITS-2401 unit and the Head of the School (HoS) has decided to hire your services to compile the results of all students in the School of Computer Science. You have been provided with an Excel file e.g. “data.xlsx” which contains the students’ details and their marks in the courses.
The first entry of the excel file (in cell A1 of the excel file) gives the Number of Students ‘nS’ whose record is stored in the excel file. Similarly, the second entry is the Number of Units ‘nU’ which each student has taken. The subsequent entries for each student are repeated as follows
• Student Name
• Student Number
• Marks for Unit 1
• Marks for Unit 2
• And so on till Marks of unit ‘nU’
Your code must perform the following tasks
Task-A: (25 marks)
Your first task is to write a function Grading.m. The first line of this function must be as follows: function [nS, nU, Result, ImpUnitsMks, TopSt, LastSt, Dist] = Grading(filename)
Details of the inputs and outputs are as under:
Input:
1. filename: The name of the XLS (or xlsx) file that contains the data. As a sample to check your code, an
excel file with the name ‘data.xls’ is provided but the file name can be changed by the user. Your function
should read the excel file provided as an input to the function to extract the data.
Outputs:
1. nS: The number of students whose record is provided in the excel file. Remember this is the first entry of
the data file.
2. nU: The number of units for each student whose record is provided in the excel file. Remember that this is
the second entry of the data file.
3. Result: This is a structure containing four fields namely “StudentName”, “StudentNumber”, “Marks” and
“Grade”. The size of this structure will depend on the number of students. The fields “StudentName” and “StudentNumber” contain the name of the student and his/her student number respectively. The field “Marks” must contain a vector of marks obtained by the student in all units in the order i.e. Unit 1 to Unit nU followed by the average marks (AvgMksi) of the student as described by equation (1).
MeanofAvg = A student can obtain the following grades:
i=1
AvgMks ) nS
AvgMksi = j=1
j
nU
(1)
∑nU Marks
where AvgMksi denotes the average marks of the ith student and Marksj are the marks obtained by the same student in the jth unit. The field “Grade” of the structure contains the grade obtained by the student. The grade is calculated as follows:
Let AvgMksi be the average marks obtained by each student in all his/her units. Let MeanofAvg be the average of AvgMksi and SDofAvg be the standard deviation of AvgMksi. The MeanofAvg is defined in equation (2)
(2)
(
∑nS
i
! ‘F’. Fail if the student fails in 3 or more individual units irrespective of his/her result in other units OR if AvgMks < (MeanofAvg – 1.5 SDofAvg). A student is considered failing in a particular Unit if s/he obtains less than 40 marks in that unit.
! ‘P’. Pass if AvgMks fall between (MeanofAvg – 1.5 SDofAvg) and (MeanofAvg – 0.5 SDofAvg) with both limits inclusive.
! ‘CR’. Credit Pass if AvgMks fall between (MeanofAvg – 0.5 SDofAvg) and (MeanofAvg + 0.5 SDofAvg) with upper limit inclusive.
! ‘D’. Distinction if AvgMks fall between (MeanofAvg +0.5 SDofAvg)and (MeanofAvg +1.5 SDofAvg) with right hand limit inclusive.
! ‘HD’. High Distinction if AvgMks > (MeanofAvg + 1.5 SDofAvg)
The variable Result containing the structure for the sample provided will look like this:
>> Result
Result =
1×156 struct array with fields:
StudentName StudentNumber Marks
Grade
And the structure for 156th students shows following details:
>> Result(156) ans =
StudentName: ‘S156’ StudentNumber: 20646624 Marks: [93 32 100 50 40 63] Grade: ‘D’
4. ImpUnitsMks. The HoS considers the first three units to be very important. This variable is a matrix that contains the marks of first three units of each student. The size of the matrix is ‘nS x 3’.
5. TopSt, LastSt. This variable contains the index numbers of the top four and last four students in the three important units only. You should find the average marks of each student in the three important units and then find the top and bottom four students. The index numbers should be in descending order with respect to the average marks of each student in the three important units.
6. Dist. This variable is a 4 x 4 matrix that contains the distance between each of the top four students and each of the last four students in the space of important units. Each element Dist(m,n) will contain distance between student m among the top four studens and student n among the last four students. For instance, Dist(2,3) will contain the distance between 2nd student in variable TopSt and 3rd student in variable LastSt. If x1, y1, z1 are the marks obtained by the first student in the important units u1, u2 and u3 respectively and x2, y2, z2 are the marks obtained by the second student in the important units u1, u2 and u3 respectively, then their distance in the space of important units is defined as :
d= ((x1−x2)2+(y1−y2)2+(z1−z2)2
(Hint: You may solve this equation using Matrix Operations taught in lecture – 8)
In summary the outputs of your function for the provided data in excel file will look like this:
[Result,ImpUnitsMks,TopSt,LastSt,nS,nU,Dist]=Grading(filename) Result =
1×156 struct array with fields:
StudentName StudentNumber Marks
Grade
ImpUnitsMks = 100 17 31
72 79 18
100 56 13
52 97 92
54 76 57
91 58 14
(Another 150 rows which have not been pasted here due to lack of space.)
TopSt = 120 139 142 90
LastSt = 115
37 10 94
nS = 156
nU = 5
Dist =
128.43 128.45 133.55 136.9 127.05 128.83 132.08 136.18 128.89 127.71 131.98 134.32 120.71 120.85 126.57 130.26
Task-B: X-Marks (5 marks)
Your code needs to generate an excel file which present the details of the students and their marks in the format presented below and under the following headings:
Student Name, Student Number, Unit1, Unit2, ….., AvgMks, Grade
Sort the students in the descending order of their Average Marks. Write this formatted and sorted data to an Excel file named as “Result.xlsx”. The code for generating this output file must be written inside the Grading.m function. Below is a screen shot of this file containing first few rows for the provided sample data.
Task-C: X-Marks (20 marks)
The HoS wants to visualise the results that you have just compiled. You are required to write another function which generates three plots. The first line of the function must be:
function PlotGrades(filename)
The input is the same filename as described in Task-A. Inside this function you should call the function Grading.m that you created in Task-A and generate the following plots using only the outputs of Grading.m. Do not copy paste the code from Task-A or perform the calculations again in this function.
• Plot-1. The histogram of AvgMksi for all students.
• Plot-2. The histogram of the grades obtained by the students.
• Plot-3. Considering the space of the marks of the Important Units, draw a 3D scatter plot of the position of each student in this space. Mark the top four students in green colour and the last four in red colour.
Remember the characteristics of good plotting taught to you in Lecture-7. The screen shots of the plots for the provided sample data are below. You will need to insert the right title, y-axis label and x-axis label for each plot.
PLOT-1
PLOT-2
PLOT-3
Note: Your code must be generic and must work with any provided excel file containing the data in the above mentioned format. Your code will be tested with a DIFFERENT data file and NOT with the same provided sample excel file.