How can i use a for loop based on a row value

I had an original matix;

A = [ 1 a b c

2 d e f

3 g h i

4 j k l ]

which i sorted by rows as;

A = [ 1 a b c

3 g h i

2 d e f

4 j k l ]

later on a for loop i want to use a specific value from A (sorted), based on the first value of each row, and not based in the number of the iteraition.

for examble

for i = 1:3

B (i) = A(i,2)

endfor

when i = 2 (second iteration)

it will return the value g ( A(2,2) ), but i want it to show the value; d ,which is the second value of the row with first corresponding number.

Answer 1

[Voss]

a = 100; b = 200; c = 300;
d = 101; e = 201; f = 301;
g = 102; h = 202; i = 302;
j = 103; k = 203; l = 303;

A = [ ...
    1 a b c; ...
    2 d e f; ...
    3 g h i; ...
    4 j k l; ...
    ]

A = 4×4

1 100 200 300 2 101 201 301 3 102 202 302 4 103 203 303

sortrows(A)

ans = 4×4

1 100 200 300 2 101 201 301 3 102 202 302 4 103 203 303

It's not clear how sorting A by rows gets you the new A, but let's just say now you have the new A:

A = [ ...
    1 a b c; ...
    3 g h i; ...
    2 d e f; ...
    4 j k l; ...
    ]

A = 4×4

1 100 200 300 3 102 202 302 2 101 201 301 4 103 203 303

for i = 1:3
    B(i) = A(i,2);
end % endfor is not a MATLAB keyword
B

B = 1×3

100 102 101

disp(B(2) == d);

   0

for i = 1:3
    B(i) = A(A(:,1) == i,2);
end
B

B = 1×3

100 101 102

disp(B(2) == d)

   1

[Emilio Salazar Sosa]

Thanks!!

B(i) = A(A(:,1) == i,2)

that line perfectly worked