Matlab Grade book help --drop one lowest score and assigning letter grade

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Hi I am building a gradebook that allows me to drop the lowest assignment score and only takes 10 assignment scores and adds all the test scores. I need to assign a letter grade to each student.
Here is some data
I am stuck on dropping the lowest score and assigning students to a grade in my function. if there is a better way of doing it without a function... please tell me...
function [sumarr] = grades(structure, field)
% FUNCTION GRADES accepts any cell array value and assigns a letter
% all data entered must be transposed from rows to colums please remember
% to transpose data example transposedata = data' ---> data = [FILE that
% was imported]
%DEFINE VARIABLES
% ii -- index variable
ii =0 ;
array =[];
for ii = 1:length(structure)
%build an array
array = [array structure(ii).(field)];
end
% if one grade is less than 2, drop the score.
% assign Letter grades
%sum of all grades
sumarr = sum(array);
end
  3 Comments

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Accepted Answer

Image Analyst
Image Analyst on 29 Nov 2014
Can you try just subtracting the min, something like
array = [structure.(field)]; % All items - no loop over ii needed.
arraySum = sum(array) - min(array);
  8 Comments
Mohammad Abouali
Mohammad Abouali on 1 Dec 2014
Edited: Mohammad Abouali on 1 Dec 2014
ImageAnalyst has already answered your question. Just one more note:
another way of grading without multiple if/else is this
levels=[59 69 79 89];
GradeLetter={ 'F', ...
'D', ...
'C', ...
'B', ...
'A'};
if (arraySum<0 || arraySum >100)
error('Imposible grade')
else
fprintf(' final grade : %.3f\t %s\n', ...
arraySum, ...
GradeLetter{imquantize(arraySum,levels)} )
end
This makes it easier to change the code and add more grade levels later, such as B+, B-, A+, A-
imquantize() is part of image processing though. You need to have that toolbox.
Iris
Iris on 5 Dec 2014
Edited: Iris on 5 Dec 2014
I am getting issues with my statements.... since I have an array with data = [93.280 70.500 67.980 23.940 95.430 89.950 85.600 94.860 88.310 75.740 82.570 73.330 92.860 91.760 83.610 88.660 82.310 87.380 76.790 69.860 90.610 86.910 97.370 73.420 ]; I apologize for not writing this solved but I wanted to make sure I get this grade assignment right.
function gradeAssignment( arraySum )
% gradeAsssignment function takes in array
% Gives the data set a letter grade outprint.
if (arraySum >= 90.0 & arraySum <= 100.0)
fprintf(' final grade : %.3f\t A\n', arraySum);
elseif (arraySum >=80.0 & arraySum <=89.0)
fprintf(' final grade : %.3f\t B\n', arraySum);
elseif (arraySum >=70.0 & arraySum <=79.0)
fprintf(' final grade : %.3f\t B\n', arraySum);
elseif (arraySum >=60.0 & arraySum <=69.0)
fprintf(' final grade : %.3f\t B\n', arraySum);
elseif (arraySum >=0.0 & arraySum <=59.0)
fprintf(' final grade : %.3f\t B\n', arraySum);
else
fprintf('ERROR: invalid grade\n');
end
end
The error that I encounter is that I run through all my data and it reads everything in the array but I get ERROR:invalid input.

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More Answers (1)

khalid
khalid on 1 Dec 2014
Do you happen to be taking this class at SMC?

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