Getting all values in the same field for different entries within a structure

Imagine I have a structure of students with certain info and their grades for different modules, looking like:

student(1).grades.math = 7;
student(2).grades.math = 9;

This student list might be any number. Is it possible to get all the different math grades in an array without a for-loop?

mathGrades = student.grades.math;

This doesn't seem to work and gives me the following error:

"Intermediate dot '.' indexing produced a comma-separated list with 2 values, but it must produce a single value when followed by subsequent indexing operations."

Answer 1

[Vilém Frynta]

Try arrayfun (use function on the struct to extract the values into the array).

An example on your data:

% Your data
student(1).grades.math = 7;
student(2).grades.math = 9;
student(3).grades.math = 6;

% Use arrayfun to extract all the math grades into vector
mathGrades = arrayfun(@(x) x.grades.math, student)

mathGrades = 1×3

7 9 6

Hope my answer was useful. If it was, I'd be happy if you could accept my answer.

[Patrick]

Thank you, this was what I was looking for!

Answer 2

[Stephen23]

"Is it possible to get all the different math grades in an array without a for-loop?"

Of course.

The simple and efficient MATLAB approach is to use comma-separated lists:

https://www.mathworks.com/matlabcentral/answers/1656435-tutorial-comma-separated-lists-and-how-to-use-them

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

student(1).grades.math = 7;
student(2).grades.math = 9;
student(3).grades.math = 6;
tmp = [student.grades];
out = [tmp.math]

out = 1×3

7 9 6

Avoid slow ARRAYFUN.