How to print a certain amount of elements in an array?

If I have an array of student ID in column1 and GPAs in column2

EX:

Info = [52211  3.55; 52922  1.79; 51939  3.33; 12140  0.81]

How can I print the first 2 elements in the array based on the GPA??

[Image Analyst]

Please describe mathematically what "first" and what "based on the GPA" means. Do you mean the first 2 rows? The first 2 rows where the GPA meets some criteria (if so, what criteria)? Do you mean the first two elements of the array, which would be Info(1:2) and be the first two elements in column 1. Do you mean something else??? You need to clarify so you don't waste our time and yours.

[madhan ravi]

@sir Image Analyst May I know why the other answer was voted so that I can improve myself.

[Image Analyst]

I could copy and paste and run Jan's code all in one shot since it defined the Info matrix. Yours would have required two copy and paste operations to try it out. I also like explicit variable names, like index rather than id, though I probably would have chosen selectedRows rather than index. Though you did choose a good name for "students_gpas". I like how he showed the Info variable as the 2-D matrix that it is, rather than the one-liner code the poster used. Not sure the sort() was needed but that was a guess on Jan's part since the poster was so vague about what was wanted. I also like his style of putting spaces around operators (equals, commas, etc.) to make the code more readable.

I like your enthusiasm. Keep it up. We can always use more good answerers here.

[madhan ravi]

Thank you for being explicit @ sir Image Analyst will work on it from next time :).

Answer 1

[madhan ravi]

An example:

id = Info(:,2) > 3 

students_gpas = Info(id,:) %students whose GPA is more than 3

[madhan ravi]

Didn’t it work?

[PJ]

I tried it but I got an error.

[madhan ravi]

>> format long g
>> Info = [52211  3.55; 52922  1.79; 51939  3.33; 12140  0.81]

Info =

                       52211                      3.55
                       52922                      1.79
                       51939                      3.33
                       12140                      0.81

>> id=Info(:,2)>3

id =

    4×1 logical array

     1
     0
     1
     0

>> students_gpas=Info(id,:) %students whose GPA is more than 3

students_gpas =

                       52211                      3.55
                       51939                      3.33

>>

[madhan ravi]

I didn't get any error

[madhan ravi]

@Pujan haven’t heard from you in a while

Answer 2

[Jan]

I'm not sure, what you are asking for, but a bold try:

Info = [52211  3.55; ...
        52922  1.79;
        51939  3.33;
        12140  0.81];
[~, index] = sort(Info(:, 2));
Output = Info(index(1:2), :)

This is the part of the matrix Info with the 2 smallest values in the 2nd column.

[PJ]

Essentially, I have a 100x2 array. Column 1 is Student IDs and Column 2 is GPA. I want to create a function in which I can print the first 25 GPAs in the array.

[Jan]

Then use my code with:

Output = Info(index(1:25), :)

if "the first" means the 25 smallest elements in sorted order.