How to replace certain array values ​​using if, for or while?

I have this 45x10 array with vallues between 0 and 2.5, I want to replace those values with letters if certain conditions are being atended.

The conditions are:

If the value is greater than 1.6, it gets grade E... if the value is greater than 1 and less than 1.6, it will receive a D grade... If the value is greater than 0.63 and less than 1, it receives a grade of C... If the value is greater than 0.315 and less than 0.63, it receives a grade of B...And finally, if the value is less than 0.315, it receives an A grade.

It can also be grades between 2 and 10 following the same ones I showed earlier (E=2, D=4, C=6, B=8 and A=10), but it would be better if the letters were used.

Answer 1

[Arka]

Hi,

You can use conditional indexing to achieve this.

This is the MATLAB code for the same:

scores = [0.2200    0.2946    0.3848    0.4869    0.5895    0.6857    0.7750    0.8591    0.9400    1.0192;
    0.3489    0.4471    0.5495    0.6561    0.7580    0.8507    0.9363    1.0182    1.0984    1.1775;
    0.3319    0.4348    0.5357    0.6343    0.7288    0.8186    0.9048    0.9892    1.0732    1.1566;
    0.2766    0.3724    0.4812    0.5927    0.6978    0.7948    0.8862    0.9756    1.0657    1.1583;
    0.2744    0.3508    0.4232    0.4876    0.5453    0.5983    0.6478    0.6950    0.7404    0.7843;
    0.2084    0.2623    0.3129    0.3615    0.4092    0.4555    0.4989    0.5384    0.5739    0.6064;
    0.2715    0.3434    0.4023    0.4543    0.5060    0.5596    0.6140    0.6672    0.7171    0.7626;
    0.1909    0.2539    0.3181    0.3812    0.4419    0.4991    0.5526    0.6032    0.6521    0.7007;
    0.1993    0.2523    0.3038    0.3547    0.4052    0.4549    0.5045    0.5555    0.6095    0.6667;
    0.3176    0.3967    0.4696    0.5367    0.5995    0.6587    0.7161    0.7749    0.8382    0.9075;
    0.2000    0.2609    0.3223    0.3814    0.4367    0.4880    0.5360    0.5830    0.6314    0.6824;
    0.3302    0.4083    0.4813    0.5507    0.6168    0.6790    0.7392    0.8011    0.8678    0.9404;
    0.3534    0.4301    0.5064    0.5810    0.6526    0.7233    0.7956    0.8706    0.9491    1.0313;
    0.3786    0.4476    0.5026    0.5516    0.6003    0.6532    0.7126    0.7784    0.8489    0.9222;
    0.3516    0.4468    0.5364    0.6223    0.7031    0.7767    0.8434    0.9051    0.9635    1.0191];
grades = zeros(size(scores));
grades(scores > 1.6) = 'E';
grades((scores > 1) & (scores <= 1.6)) = 'D';
grades((scores > 0.63) & (scores <= 1)) = 'C';
grades((scores > 0.315) & (scores <= 0.63)) = 'B';
grades(scores < 0.315) = 'A';
scores = char(grades)

Now you can access individual grades using matrix indexing. To access the grade in the ith row and jth column:

scores(i,j)

To learn more about conditional indexing, please refer to the MathWorks documentation below:

https://www.mathworks.com/help/matlab/matlab_prog/find-array-elements-that-meet-a-condition.html