how to plot histogram from table?

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YYYYAAAAMMMM
YYYYAAAAMMMM 2017-9-18
回答： Peter Perkins 2017-9-21
Hi i am new for Matlab, i got a table and want histogram to show the distribution of student grade. How can i plot it?
format longG;
data=xlsread('data.xls');
StudentID=data(:,1);
%double(ID);
no_of_std=length(StudentID);
Coursework=data(:,2);
Exam=data(:,3);
FinalMarks=0.4*Coursework + 0.6*Exam;
a= input('Enter the scale boundary for A: ');
b= input('Enter the scale boundary for B: ');
c= input('Enter the scale boundary for C: ');
d= input('Enter the scale boundary for D: ');
N=length(FinalMarks);
FinalGrade = cell(N,1);
for i = 1:N
if FinalMarks(i) >= a
FinalGrade{i} = 'A';
elseif FinalMarks(i) >= b % final(i)<A has been exclude before already
FinalGrade{i} = 'B';
elseif FinalMarks(i) >= c
FinalGrade{i} = 'C';
elseif FinalMarks(i) >= d
FinalGrade{i} = 'D';
else
FinalGrade{i} = 'F';
end % Close the IF branches
end % Close the FOR loop
count_A = sum(strcmp(FinalGrade,'A')); % this part to count no. of A,B,C,D,F.
count_B = sum(strcmp(FinalGrade,'B'));
count_C = sum(strcmp(FinalGrade,'C'));
count_D = sum(strcmp(FinalGrade,'D'));
count_F = sum(strcmp(FinalGrade,'F'));
t1=table(StudentID, Coursework, Exam, FinalMarks, FinalGrade);
result= sortrows(t1, 'FinalMarks', 'descend');
display(result);
The histogram i want is x-axis(FinalGrade) become: A B C D F and y-axis become corresponding no. of students.
  1 个评论
Akira Agata
Akira Agata 2017-9-19
Seems that bar will generate what you want to obtain, like "bar([count_A, count_B, count_C, count_D, count_F)"

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采纳的回答

Peter Perkins
Peter Perkins 2017-9-21
This doesn't really have anything to do with tables, you just want a histogram on discrete values.
Use a categorical variable:
>> FinalGrade = categorical(randi(5,100,1),1:5,{'A' 'B' 'C' 'D' 'F'});
>> histogram(FinalGrade)
If you version of MATLAB doesn't support histogram on categorical, use hist instead.

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