Create an array based on another array's input

Hello, I had this question in Class last weekend, but I seemed not capable of solving it ,despite it being pretty easy relatively (I had to use vectorized code) it wamted me to convert an array of scores into grades using vectorized code. My regular sol. Would be:

X=input('insert array');
j=1;
For i=1:length(x)
If x(i) >=90
  F(j) == 'a';
  j=j+1;
Elseif x(i) >= 80 &       x(i)<= 90
 F(j)== 'b';
End
End

But as you probably know this is not vectorized. If possible I would want to know multiple ways of solving that, so I can expand my understanding of matlab and vectors in general. Thanks alot and excuse my english.

Answer 1

[Roger Stafford]

Use the ‘histc’ function, [~,ix] = histc(x,grade_ranges), then use ix to index into a vector [‘A’,’B’,’C’,’D’.’F’].

[Ahmed Khalifa]

I really cant understand this function at all

Answer 2

[Walter Roberson]

gradebounds = [0 80 90];
gradeletters = {'f', 'b', 'a'};

gradeidx = interp1(gradebounds, 1:length(gradebounds), x(:), 'previous', 'extrap');

grades = gradeletters(gradeidx);