if statement in for loop with cell arrays

I have this problem with matlab, I have to assign letter grades to the scores I have, but I couldn't do it. Can anybody help?

s.name={'Seda','Ayça','Deniz','Kerem','Mete'}
s.score={'90','45','68','86','82'}
N=lenght(s.score)
for i = 1:1:N
    if (i)<100 & (i)>=90
       grades(i)='A'
    elseif (i)<90 & (i)>=80
       grades(i) ='B'
    elseif (i)<80 & (i)>=70
       grades ='C'
    elseif (i)<70 & (i)>=60
       grades ='D'
    else 
       grades = 'F'
    end
end

[dpb]

You wrote the test on the variable i which isn't even defined in your code...

if (i)<100 & (i)>=90
  ...

You need to test the score for each element in the struct score field, but you could do so without a loop as well...unless using for...end is part of the assignment, of course.

[Guillaume]

In addition, what is the purpose of the () brackets around i? They don't do anything at all, just make the code harder to read.

Note that the whole thing can be achieved in just one line by a call to discretize.

[dpb]

Also, those would be prime candidates to be categorical ordinal variables instead of character if we're looking a niceties... :)

[Fabio Freschi]

Can you have char varaible as values in discretize?

[Guillaume]

Can you have char varaible as values in discretize?

Yes,

>> score = [90, 45, 68, 86, 82];
>> discretize(score, [0 60 70 80 90 100], {'F', 'D', 'C', 'B', 'A'})
ans =
  1×5 cell array
    {'A'}    {'F'}    {'D'}    {'B'}    {'B'}

All discretize does is index the values array with the indices it would normally return. You can have pretty much anything that can be indexed as values.

Answer 1

[Fabio Freschi]

To stick with the OP snippet

1. I added semicolons all over the place
2. I changed the variable type in s.score to doubles
3. I preallocated the grades variable as string array
4. I changed the check on (i) with s.score{i}
5. I added <= 100 to include also the possibility of 100 score
6. I changed the single & to double && for logical scalar values

s.name={'Seda','Ayça','Deniz','Kerem','Mete'};
s.score={90,45,68,86,82};
 
N=length(s.score);
 
grades = strings(N,1);
 
for i = 1:1:N
    if s.score{i}<=100 && s.score{i}>=90
       grades(i)='A';
    elseif s.score{i}<90 && s.score{i}>=80
       grades(i) ='B';
    elseif s.score{i}<80 && s.score{i}>=70
       grades(i) ='C';
    elseif s.score{i}<70 && s.score{i}>=60
       grades(i) ='D';
    else 
       grades(i) = 'F';
    end
end