Writing a find function

Hello all,

I am trying to run a function that will use the "find" function to separate grades

i have my code below, but I dont know what I seem to be doing wrong.

function [out_orig, out_new] = parse_grades 

scores = 100*rand(50,1);

ind1 = find(scores >= 90);  %A 
ind2 = find(scores <= 80) && ( scores < 90 ); % B
ind3 = find(scores <=70) && (scores < 80); % C
ind4 = find(scores <= 60) && ( scores <70); % D
ind5 = find (scores <60); % f 



vec_new(ind1) = 'A';
vec_new(ind2) = 'B' ;
vec_new(ind3) = 'C' ;
vec_new(ind4) = 'D' ;
vec_new(ind5) = 'F'; 

out_orig = scores;
out_new = vec_new ;


end 

the error I am getting is

Operands to the || and && operators must be convertible to logical scalar values.

Error in parse_grades (line 6)

ind2 = find(scores <= 80) && ( scores < 90 ); % B

[Ameer Hamza]

You haven't defined A, B, C, D, and F inside the function.

[Nicholas Deosaran]

Okay, how would I fix that?

[Ruger28]

I think you meant to say:

vec_new(ind1) = 'A';
vec_new(ind2) = 'B'; 
vec_new(ind3) = 'C'; 
vec_new(ind4) = 'D'; 
vec_new(ind5) = 'F'; 

not saying this will solve your problems, though.

[Nicholas Deosaran]

Hey, thank you for that.

The problem I was having which I should of stated above is:

Operands to the || and && operators must be convertible to logical scalar values.

Error in parse_grades (line 6)

ind2 = (scores <= 80) && ( scores < 90 ); % B

Answer 1

[KSSV]

You can proceed something like htis:

score = randperm(100,1) 
if score >=90
    grade = 'A' ;
  elseif (score >= 80) & (score < 90 )
    grade = 'B' ;
  elseif (score >= 70) & (score < 80)
    grade = 'C' ; 
  elseif (score >= 60) & (score < 70 )
    grade = 'D' ;
  else 
    grade = 'E' ;
end
  grade

If you want score to be a vector, proceed like this:

score = randperm(100,10) ;
idx = zeros(size(score)) ; 

idx(score >= 90) = 1 ; 
idx(score >= 80 & score < 90) = 2 ; 
idx(score >= 70 & score < 80) = 3 ; 
idx(score >= 60 & score < 70) = 4 ; 
idx(idx==0) = 5 ; 

grade = {'A', 'B', 'C', 'D', 'E'} ;
  
  
iwant = grade(idx)

[Nicholas Deosaran]

Yes, but I will like to use it with the "Find" function if possible?

[KSSV]

I have edited the answer...with logical indices..plese check.

[Nicholas Deosaran]

Can it be used it find?

[KSSV]

score = randperm(100,10) ;
idx1 = find(score > 90)   % A grade 
idx2 = find(score >= 60 & score < 70) % C Grade 

[Nicholas Deosaran]

is the idx1 --- > idx= zeros(size(score)); ??

[Stephen23]

"Can it be used it find?"

Using find is less efficient than the simple logical indexing that KSSV's answer shows.