Extract cell value based on row contents

I have a table with 4 columns (id1, id2, HB, and FENE) and many thousands of rows. From this I would like to create a new table of HB data, extracted if the id1 and id2 contain particular values. For instance:

id1 id2 HB FENE

1 28 0.718 281

1 31 0.572 256

1 07 0.182 413

2 28 0.271 361

2 31 0.725 249

2 07 0.012 992

1 28 0.381 438

2 31 0.991 913

if I am interested in the id combinations of [1,28] and [2,31], I want to produce the table:

1+28 2+31

0.718 0.725

0.381 0.991

In the dataset there will always be the same number of id combinations (i.e. if there are five rows containing [1,28], there are also five rows of [2,31]).

My current process is:

id1 = [1 2 3 4 5]
id2 = [28 31 34 37 40]

dataFile = file.txt

dataOutput = zeros(1,5)

for k = 1:5
    head1 = strand1(k)+"+"+strand2(k)
    
    if dataFile{:,1} == strand1(k) 
        if dataFile{:,2} == strand2(k)  %both conditions must be true to proceed
            ?? extract data from this row, in col 3, and append to dataOutput in col k, new row
        end
    end
    %loops in k=1 until all instances are found
        %do i have to define how many times to loop for k=1?
end

outputTable = array2table(dataOutput)
outputTable.Properties.VariableNames(1:5) = {'head1','head2','head3','head4','head5'}

Thank you very much for any pointers or advice.

Answer 1

[Askic V]

Here is one example that should give you an idea how to proceed:

A = [1       28      0.718   281
1       31      0.572   256
1       07      0.182   413
2       28      0.271   361
2       31      0.725   249
2       07      0.012   992
1       28      0.381   438
2       31      0.991   913];
ind = find((A(:,1) == 1) & (A(:,2) == 28))

ind = 2×1

1 7

A_1_28 = A(ind,3)

A_1_28 = 2×1

0.7180 0.3810

[Karuna Skipper]

Thanks very much!!