Convert final grade letter into categorical array.

Class_List = readcell('ClassList_2600.xls');
 N = size(Class_List);
 num_rows = N(1);
 
 
for i = 2:N
    Test = ((Class_List{i,4} + Class_List{i,5}) / 2) * 0.1;
    
    Assignment = Class_List{i,3} * 0.1;
    
    Midterm = Class_List{i,6} * 0.3;
    
    Final = Class_List{i,7} * 0.5;
    
    grade = round(Test + Assignment + Midterm + Final);
    
    if grade >= 90
        Class_List{i,8} = grade;
        Class_List{i,9} = {'A+'};
        
    elseif grade >= 80 && grade <= 89
        Class_List{i,8} = grade;
        Class_List{i,9} = {'A'};
        
    elseif grade >= 70 && grade <= 79
        Class_List{i,8} = grade;
        Class_List{i,9} = {'B'};
        
    elseif grade >= 60 && grade <= 69
        Class_List{i,8} = grade;
        Class_List{i,9} = {'C'};
        
    elseif grade >= 50 && grade <= 59
        Class_List{i,8} = grade;
        Class_List{i,9} = {'D'};
        
    elseif grade < 50
        Class_List{i,8} = grade;
        Class_List{i,9} = {'E'};
        
    end
        
end

a = Class_List(:,9);

pie = categorical(a);

So basically, I have a 26x9 cell array that shows a class list. It contains names, student ID, marks for related work, their final grade number and letter associated with it (i.e A, B, C, D, etc). I don't know how to use the categorical function. What I have above is my work.

Answer 1

[Scott MacKenzie]

% test data containing student letter grades
C = { 'A' 'C' 'D' 'A' 'D' 'B' 'B' 'C' 'A' };

% define C to be categorical
C = categorical(C);

% display the categories
categories(C)

ans = 4×1 cell array
    {'A'}
    {'B'}
    {'C'}
    {'D'}

% output number of students in each letter grade category
n = countcats(C)

n = 1×4

3 2 2 2

% present in pie chart
pie(n)

[Asad Ahmed]

I have a question. Is it possible to use the categorical function on a column of a cell array?

[Scott MacKenzie]

Yes

Answer 2

[Steven Lord]

I would make a vector of grade numbers then use discretize to create a categorical array from that vector of grade numbers. See the "Group Data into Categorical Array" example on the documentation page for the discretize function as a model you can use.