Extract rows from 2 different matrices with different dimensions using If statement

Hi guys. Hoping that you're all ok.

For my project i need to every equal runID (column 5 on both matrices) to extract the rows that contains the higher value of the energy (column 3 on both matrices) in the same eventID (column 2 on both matrices).

Example, for a runID == 0, e need to extract the higher value of the energy on both matrices in the same eventID == 6. Using the .txt files i've attached, that corresponds to the first row in both matrices.

This is my current code:

for i=[1:99]
    
    
    file_number=sprintf('%d',i);
    R = fileread(strcat('right',num2str(file_number),'.txt'));
    R(R == '*') = '';
    AR = cell2mat( textscan(R, '%f %f %f %f %f %f', 'headerlines', 4));

    L = fileread(strcat('left',num2str(file_number),'.txt'));
    L(L == '*') = '';
    AL = cell2mat( textscan(L, '%f %f %f %f %f %f', 'headerlines',4));
    
  
    for n=[0:max(AR(:,5))];
       if AR(:,5)==n;
           if AL(:,5)==n;
              idx=find(AR(:,2)==AL(:,2))
              
           end
       end
        
    end
end

I've already tried different ways to exctrat what i need but i found always a different problem every time.

Thanks in advance.

Answer 1

[Jan]

if AR(:,5)==n;

This is a vector in the condition. Therefore Matlab inserts an all() implicitly, because conditions of if statements must be scalar.

I guess you want:

    indexR = (AR(:, 5) == n);
    ARn    = AR(inbdexR, 2);

I do not completely understand, which problem you want to solve and what you want as output.

A hint: file_number is a string already, so omit num2str. Replace

    file_number=sprintf('%d',i);
    R = fileread(strcat('right',num2str(file_number),'.txt'));    

by the simpler:

    file = sprintf('right%d.txt', i);
    R    = fileread(file);

[David Martins]

    indexR = (AR(:, 5) == n);
    ARn    = AR(inbdexR, 2);

This is brilliant! It does exactly what i want it to do as a first step. Your explanation about the if statements is the true hero here. I was not aware of that.

What i really want is to have the entire row witch contain the higer energy value (column 3) from both matrices in each eventID (column 2). Some files have different eventID within the same runID. Example

ARn=[6710	0	0.00218000000000000	    7	431	    2203.10470000000
    6711	0	7.49900000000000e-06	8	431	    2203.10470000000
    6712	2	0.00217740000000000	    9	431	    2203.10860000000
    6713	2	2.49900000000000e-06	10	431	    2203.10860000000
    6714	2	7.49900000000000e-06	8	431	    2203.10860000000]

ALn=[11892	0	0.00701500000000000	    7	431	    2203.10470000000
    11893	0	4.24900000000000e-05	6	431	    2203.10470000000
    11894	0	3.99900000000000e-05	8	431	    2203.10470000000
    11895	0	4.99900000000000e-06	5	431	    2203.10470000000
    11896	0	2.49900000000000e-06	9	431	    2203.10470000000
    11897	2	0.00592990000000000	    9	431	    2203.10860000000
    11898	2	1.99900000000000e-05	10	431	    2203.10860000000
    11899	2	1.99900000000000e-05	8	431	    2203.10860000000]

In this example, for a runID == 0, i want to extract the first from both matrices and for runID == 2, extract the third row from ARn and the sixth eow from ALn.